Category Archives: Instrumentation and Methods for Astrophysics

Modeling noise propagation in Fourier-filtering wavefront sensing, fundamental limits and quantitative comparison [IMA]

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http://arxiv.org/abs/2212.13577


Adaptive optics (AO) is a technique allowing to drastically improve ground-based telescopes angular resolution. The wavefront sensor (WFS) is one of the key components of such systems, driving the fundamental performance limitations. In this paper, we focus on a specific class of WFS: the Fourier-filtering wavefront sensors (FFWFS). This class is known for its extremely high sensitivity. However, a clear and comprehensive noise propagation model for any kind of FFWFS is lacking. Considering read-out noise and photon noise, we derive a simple and comprehensive model allowing to understand how these noises propagates in the phase reconstruction in the linear framework. This new noise propagation model works for any kind of FFWFS, and allows to revisit the fundamental sensitivity limit of these sensors. Furthermore, a new comparison between widely used FFWFS is held. We focus on the two main used FFWFS classes: the Zernike WFS (ZWFS) and the pyramid WFS (PWFS), bringing new understanding of their behavior.

Read this paper on arXiv…

V. Chambouleyron, O. Fauvarque, C. Plantet, et. al.
Thu, 29 Dec 22
47/47

Comments: N/A

KNIFE, KAshima Nobeyama InterFErometer [IMA]

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http://arxiv.org/abs/2212.13331


By connecting two antennas, Kashima 34~m and Nobeyama 45~m, an east-west baseline of 200~km is formed. At that time, because Nobeyama 45~m had the world’s number one sensitivity in the 43~GHz band, and also Kashima 34~m was the world’s third-largest one, the Kashima-Nobeyama baseline provided the highest sensitivity at 43~GHz VLBI (Figure 1). The construction of the Kashima 34~m antenna began in 1988, also almost at the same time, a domestic project of mm-VLBI (KNIFE, Kashima Nobeyama INterFrermeter) started. Nobeyama Radio Observatory provided the first cooled-HEMT 43~GHz receiver in the world to the Kashima 34~m. In October 1989, the first fringe at 43~GHz was detected. We here review the achievements of the KNIFE at that time.

Read this paper on arXiv…

M. Miyoshi
Thu, 29 Dec 22
38/47

Comments: 5 pages, 5 figures, manuscript in Proceedings of the 18th NICT TDC Symposium (Kashima, October 1, 2020)

New Particle Identification Approach with Convolutional Neural Networks in GAPS [IMA]

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http://arxiv.org/abs/2212.13454


The General Antiparticle Spectrometer (GAPS) is a balloon-borne experiment that aims to measure low-energy cosmic-ray antiparticles. GAPS has developed a new antiparticle identification technique based on exotic atom formation caused by incident particles, which is achieved by ten layers of Si(Li) detector tracker in GAPS. The conventional analysis uses the physical quantities of the reconstructed incident and secondary particles. In parallel with this, we have developed a complementary approach based on deep neural networks. This paper presents a new convolutional neural network (CNN) technique. A three-dimensional CNN takes energy depositions as three-dimensional inputs and learns to identify their positional/energy correlations. The combination of the physical quantities and the CNN technique is also investigated. The findings show that the new technique outperforms existing machine learning-based methods in particle identification.

Read this paper on arXiv…

M. Yamatani, Y. Nakagami, H. Fuke, et. al.
Thu, 29 Dec 22
39/47

Comments: 7 pages, 10 figures

Modeling noise propagation in Fourier-filtering wavefront sensing, fundamental limits and quantitative comparison [IMA]

Posted on by

http://arxiv.org/abs/2212.13577


Adaptive optics (AO) is a technique allowing to drastically improve ground-based telescopes angular resolution. The wavefront sensor (WFS) is one of the key components of such systems, driving the fundamental performance limitations. In this paper, we focus on a specific class of WFS: the Fourier-filtering wavefront sensors (FFWFS). This class is known for its extremely high sensitivity. However, a clear and comprehensive noise propagation model for any kind of FFWFS is lacking. Considering read-out noise and photon noise, we derive a simple and comprehensive model allowing to understand how these noises propagates in the phase reconstruction in the linear framework. This new noise propagation model works for any kind of FFWFS, and allows to revisit the fundamental sensitivity limit of these sensors. Furthermore, a new comparison between widely used FFWFS is held. We focus on the two main used FFWFS classes: the Zernike WFS (ZWFS) and the pyramid WFS (PWFS), bringing new understanding of their behavior.

Read this paper on arXiv…

V. Chambouleyron, O. Fauvarque, C. Plantet, et. al.
Thu, 29 Dec 22
47/47

Comments: N/A

CUBES: a UV spectrograph for the future [IMA]

Posted on by

http://arxiv.org/abs/2212.12791


In spite of the advent of extremely large telescopes in the UV/optical/NIR range, the current generation of 8-10m facilities is likely to remain competitive at ground-UV wavelengths for the foreseeable future. The Cassegrain U-Band Efficient Spectrograph (CUBES) has been designed to provide high-efficiency (>40%) observations in the near UV (305-400 nm requirement, 300-420 nm goal) at a spectral resolving power of R>20,000, although a lower-resolution, sky-limited mode of R ~ 7,000 is also planned.
CUBES will offer new possibilities in many fields of astrophysics, providing access to key lines of stellar spectra: a tremendous diversity of iron-peak and heavy elements, lighter elements (in particular Beryllium) and light-element molecules (CO, CN, OH), as well as Balmer lines and the Balmer jump (particularly important for young stellar objects). The UV range is also critical in extragalactic studies: the circumgalactic medium of distant galaxies, the contribution of different types of sources to the cosmic UV background, the measurement of H2 and primordial Deuterium in a regime of relatively transparent intergalactic medium, and follow-up of explosive transients.
The CUBES project completed a Phase A conceptual design in June 2021 and has now entered the Phase B dedicated to detailed design and construction. First science operations are planned for 2028. In this paper, we briefly describe the CUBES project development and goals, the main science cases, the instrument design and the project organization and management.

Read this paper on arXiv…

S. Covino, S. Cristiani, J. Alcala’, et. al.
Tue, 27 Dec 22
1/30

Comments: Proceedings for the HACK100 conference, Trieste, June 2022. arXiv admin note: substantial text overlap with arXiv:2208.01672

It's your software! Get it cited the way you want! [IMA]

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http://arxiv.org/abs/2212.12683


Are others using software you’ve written in their research and citing it as you want it to be cited? Software can be cited in different ways, some good, and some not good at all for tracking and counting citations in indexers such as ADS and Clarivate’s Web of Science. Generally, these resources need to match citations to resources, such as journal articles or software records, they ingest. This presentation covered common reasons as to why a code might not be cited well (in a trackable/countable way), which citation methods are trackable, how to specify this information for your software, and where this information should be placed. It also covered standard software metadata files, how to create them, and how to use them. Creating a metadata file, such as a CITATION.cff or codemeta.json, and adding it to the root of your code repo is easy to do with the ASCL’s metadata file creation overlay, and will help out anyone wanting to give you credit for your computational method, whether it’s a huge carefully-written and tested package, or a short quick-and-dirty-but-oh-so-useful code.

Read this paper on arXiv…

A. Allen
Tue, 27 Dec 22
7/30

Comments: 2 figures, 1 table

Using the Astrophysics Source Code Library: Find, cite, download, parse, study, and submit [IMA]

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http://arxiv.org/abs/2212.12682


The Astrophysics Source Code Library (ASCL) contains 3000 metadata records about astrophysics research software and serves primarily as a registry of software, though it also can and does accept code deposit. Though the ASCL was started in 1999, many astronomers, especially those new to the field, are not very familiar with it. This hands-on virtual tutorial was geared to new users of the resource to teach them how to use the ASCL, with a focus on finding software and information about software not only in this resource, but also by using Google and NASA’s Astrophysics Data System (ADS). With computational methods so important to research, finding these methods is useful for examining (for transparency) and possibly reusing the software (for reproducibility or to enable new research). Metadata about software is useful for, for example, knowing how to cite software when it is used for research and studying trends in the computational landscape. Though the tutorial was primarily aimed at new users, advanced users were also likely to learn something new.

Read this paper on arXiv…

A. Allen
Tue, 27 Dec 22
13/30

Comments: 4 figures

The contribution of the modern amateur astronomer to the science of astronomy [IMA]

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http://arxiv.org/abs/2212.12543


An amateur astronomer in the modern world has the opportunity not only to make visual observations for own interest, but can make scientific astronomical observations and new discoveries in astronomy.
In my example, as amateur astronomer and only through self-education, I inform about my discoveries: of the possible dwarf nova on the old digitized photographic plates and of new variable stars from sky surveys data by means of data mining; how I discovered (in the images of the sky surveys): astronomical transients, supernovae, planetary nebula candidates and new binary systems in the data of Gaia DR2; I describe my discoveries of three novae in the Andromeda Galaxy.
I report about some of my scientific observations using remote telescopes: of superhumps of cataclysmic variable stars; of echo outburst of AM CVn star; of maximum brightness of blazars; of optical afterglows of gamma-ray bursts (including GRB 221009A); of microlensing events; of rotation of near-Earth asteroid 2022 AB. I also describe my photometric follow-up observations of novae (including V1405 Cas and V1674 Her) and my astrometric observations of Solar System objects (including the confirmation of objects posted at the Confirmation Pages of the Minor Planet Center) including observations of comet 2I/Borisov, asteroids 2020 AV2 and (65803) Didymos. I also describe some of my observations of occultations: of the star by asteroid (159) Aemilia, of the star by Saturn’s moon Titan and of Uranus by the Moon during total lunar eclipse on November 8, 2022; and visual observations of variable stars, meteors and sunspots (including during the transit of Venus in 2012).
Some of my data already used in scientific papers, others were sent to the databases. I share my experience of discovery and research of astronomical objects and in my example, I show that an amateur astronomer can make a real contribution to the science.

Read this paper on arXiv…

F. Romanov
Tue, 27 Dec 22
16/30

Comments: 22 pages, 32 figures, 1 table. Presented as e-Poster during the IAUGA 2022: XXXIst General Assembly of the International Astronomical Union (August 2-11, 2022, in Busan, Republic of Korea), at the IAU Focus Meeting 10 “Synergy of Small Telescopes and Large Surveys for Solar System and Exoplanetary Bodies Research”

Thermal Control System to Easily Cool the GAPS Balloon-borne Instrument on the Ground [IMA]

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http://arxiv.org/abs/2212.12862


This study developed a novel thermal control system to cool detectors of the General AntiParticle Spectrometer (GAPS) before its flights. GAPS is a balloon-borne cosmic-ray observation experiment. In its payload, GAPS contains over 1000 silicon detectors that must be cooled below $-40^{\circ}\mbox{C}$. All detectors are thermally coupled to a unique heat-pipe system (HPS) that transfers heat from the detectors to a radiator. The radiator is designed to be cooled below $-50^{\circ}\mbox{C}$ during the flight by exposure to space. The pre-flight state of the detectors is checked on the ground at 1 atm and ambient room temperature, but the radiator cannot be similarly cooled. The authors have developed a ground cooling system (GCS) to chill the detectors for ground testing. The GCS consists of a cold plate, a chiller, and insulating foam. The cold plate is designed to be attached to the radiator and cooled by a coolant pumped by the chiller. The payload configuration, including the HPS, can be the same as that of the flight. The GCS design was validated by thermal tests using a scale model. The GCS design is simple and provides a practical guideline, including a simple estimation of appropriate thermal insulation thickness, which can be easily adapted to other applications.

Read this paper on arXiv…

H. Fuke, S. Okazaki, A. Kawachi, et. al.
Tue, 27 Dec 22
20/30

Comments: 8 pages, 14 figures, 3 tables

The contribution of the modern amateur astronomer to the science of astronomy [IMA]

Posted on by

http://arxiv.org/abs/2212.12543


An amateur astronomer in the modern world has the opportunity not only to make visual observations for own interest, but can make scientific astronomical observations and new discoveries in astronomy.
In my example, as amateur astronomer and only through self-education, I inform about my discoveries: of the possible dwarf nova on the old digitized photographic plates and of new variable stars from sky surveys data by means of data mining; how I discovered (in the images of the sky surveys): astronomical transients, supernovae, planetary nebula candidates and new binary systems in the data of Gaia DR2; I describe my discoveries of three novae in the Andromeda Galaxy.
I report about some of my scientific observations using remote telescopes: of superhumps of cataclysmic variable stars; of echo outburst of AM CVn star; of maximum brightness of blazars; of optical afterglows of gamma-ray bursts (including GRB 221009A); of microlensing events; of rotation of near-Earth asteroid 2022 AB. I also describe my photometric follow-up observations of novae (including V1405 Cas and V1674 Her) and my astrometric observations of Solar System objects (including the confirmation of objects posted at the Confirmation Pages of the Minor Planet Center) including observations of comet 2I/Borisov, asteroids 2020 AV2 and (65803) Didymos. I also describe some of my observations of occultations: of the star by asteroid (159) Aemilia, of the star by Saturn’s moon Titan and of Uranus by the Moon during total lunar eclipse on November 8, 2022; and visual observations of variable stars, meteors and sunspots (including during the transit of Venus in 2012).
Some of my data already used in scientific papers, others were sent to the databases. I share my experience of discovery and research of astronomical objects and in my example, I show that an amateur astronomer can make a real contribution to the science.

Read this paper on arXiv…

F. Romanov
Tue, 27 Dec 22
4/30

Comments: 22 pages, 32 figures, 1 table. Presented as e-Poster during the IAUGA 2022: XXXIst General Assembly of the International Astronomical Union (August 2-11, 2022, in Busan, Republic of Korea), at the IAU Focus Meeting 10 “Synergy of Small Telescopes and Large Surveys for Solar System and Exoplanetary Bodies Research”

Using the Astrophysics Source Code Library: Find, cite, download, parse, study, and submit [IMA]

Posted on by

http://arxiv.org/abs/2212.12682


The Astrophysics Source Code Library (ASCL) contains 3000 metadata records about astrophysics research software and serves primarily as a registry of software, though it also can and does accept code deposit. Though the ASCL was started in 1999, many astronomers, especially those new to the field, are not very familiar with it. This hands-on virtual tutorial was geared to new users of the resource to teach them how to use the ASCL, with a focus on finding software and information about software not only in this resource, but also by using Google and NASA’s Astrophysics Data System (ADS). With computational methods so important to research, finding these methods is useful for examining (for transparency) and possibly reusing the software (for reproducibility or to enable new research). Metadata about software is useful for, for example, knowing how to cite software when it is used for research and studying trends in the computational landscape. Though the tutorial was primarily aimed at new users, advanced users were also likely to learn something new.

Read this paper on arXiv…

A. Allen
Tue, 27 Dec 22
5/30

Comments: 4 figures

Thermal Control System to Easily Cool the GAPS Balloon-borne Instrument on the Ground [IMA]

Posted on by

http://arxiv.org/abs/2212.12862


This study developed a novel thermal control system to cool detectors of the General AntiParticle Spectrometer (GAPS) before its flights. GAPS is a balloon-borne cosmic-ray observation experiment. In its payload, GAPS contains over 1000 silicon detectors that must be cooled below $-40^{\circ}\mbox{C}$. All detectors are thermally coupled to a unique heat-pipe system (HPS) that transfers heat from the detectors to a radiator. The radiator is designed to be cooled below $-50^{\circ}\mbox{C}$ during the flight by exposure to space. The pre-flight state of the detectors is checked on the ground at 1 atm and ambient room temperature, but the radiator cannot be similarly cooled. The authors have developed a ground cooling system (GCS) to chill the detectors for ground testing. The GCS consists of a cold plate, a chiller, and insulating foam. The cold plate is designed to be attached to the radiator and cooled by a coolant pumped by the chiller. The payload configuration, including the HPS, can be the same as that of the flight. The GCS design was validated by thermal tests using a scale model. The GCS design is simple and provides a practical guideline, including a simple estimation of appropriate thermal insulation thickness, which can be easily adapted to other applications.

Read this paper on arXiv…

H. Fuke, S. Okazaki, A. Kawachi, et. al.
Tue, 27 Dec 22
23/30

Comments: 8 pages, 14 figures, 3 tables

It's your software! Get it cited the way you want! [IMA]

Posted on by

http://arxiv.org/abs/2212.12683


Are others using software you’ve written in their research and citing it as you want it to be cited? Software can be cited in different ways, some good, and some not good at all for tracking and counting citations in indexers such as ADS and Clarivate’s Web of Science. Generally, these resources need to match citations to resources, such as journal articles or software records, they ingest. This presentation covered common reasons as to why a code might not be cited well (in a trackable/countable way), which citation methods are trackable, how to specify this information for your software, and where this information should be placed. It also covered standard software metadata files, how to create them, and how to use them. Creating a metadata file, such as a CITATION.cff or codemeta.json, and adding it to the root of your code repo is easy to do with the ASCL’s metadata file creation overlay, and will help out anyone wanting to give you credit for your computational method, whether it’s a huge carefully-written and tested package, or a short quick-and-dirty-but-oh-so-useful code.

Read this paper on arXiv…

A. Allen
Tue, 27 Dec 22
29/30

Comments: 2 figures, 1 table

CUBES: a UV spectrograph for the future [IMA]

Posted on by

http://arxiv.org/abs/2212.12791


In spite of the advent of extremely large telescopes in the UV/optical/NIR range, the current generation of 8-10m facilities is likely to remain competitive at ground-UV wavelengths for the foreseeable future. The Cassegrain U-Band Efficient Spectrograph (CUBES) has been designed to provide high-efficiency (>40%) observations in the near UV (305-400 nm requirement, 300-420 nm goal) at a spectral resolving power of R>20,000, although a lower-resolution, sky-limited mode of R ~ 7,000 is also planned.
CUBES will offer new possibilities in many fields of astrophysics, providing access to key lines of stellar spectra: a tremendous diversity of iron-peak and heavy elements, lighter elements (in particular Beryllium) and light-element molecules (CO, CN, OH), as well as Balmer lines and the Balmer jump (particularly important for young stellar objects). The UV range is also critical in extragalactic studies: the circumgalactic medium of distant galaxies, the contribution of different types of sources to the cosmic UV background, the measurement of H2 and primordial Deuterium in a regime of relatively transparent intergalactic medium, and follow-up of explosive transients.
The CUBES project completed a Phase A conceptual design in June 2021 and has now entered the Phase B dedicated to detailed design and construction. First science operations are planned for 2028. In this paper, we briefly describe the CUBES project development and goals, the main science cases, the instrument design and the project organization and management.

Read this paper on arXiv…

S. Covino, S. Cristiani, J. Alcala’, et. al.
Tue, 27 Dec 22
30/30

Comments: Proceedings for the HACK100 conference, Trieste, June 2022. arXiv admin note: substantial text overlap with arXiv:2208.01672

First Flight Performance of the Micro-X Microcalorimeter X-Ray Sounding Rocket [IMA]

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http://arxiv.org/abs/2212.12064


The flight of the Micro-X sounding rocket on July 22, 2018 marked the first operation of Transition-Edge Sensors and their SQUID readouts in space. The instrument combines the microcalorimeter array with an imaging mirror to take high-resolution spectra from extended X-ray sources. The first flight target was the Cassiopeia~A Supernova Remnant. While a rocket pointing malfunction led to no time on-target, data from the flight was used to evaluate the performance of the instrument and demonstrate the flight viability of the payload. The instrument successfully achieved a stable cryogenic environment, executed all flight operations, and observed X-rays from the on-board calibration source. The flight environment did not significantly affect the performance of the detectors compared to ground operation. The flight provided an invaluable test of the impact of external magnetic fields and the instrument configuration on detector performance. This flight provides a milestone in the flight readiness of these detector and readout technologies, both of which have been selected for future X-ray observatories.

Read this paper on arXiv…

J. Adams, R. Baker, S. Bandler, et. al.
Mon, 26 Dec 22
15/39

Comments: N/A

J-PLUS Tracking Tool: Scheduler and Tracking software for the Observatorio Astrofísico de Javalambre (OAJ) [IMA]

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http://arxiv.org/abs/2212.12270


The Javalambre Photometric Local Universe Survey (J-PLUS) is an ongoing 12 band photometric optical survey, observing thousands of square degrees of the Northern Hemisphere from the dedicated JAST80 telescope at the Observatorio Astrof\’isico de Javalambre (OAJ). Observational strategy is a critical point in this large survey. To plan the best observations, it is necessary to select pointings depending on object visibility, the pointing priority and status and location and phase of the Moon. In this context, the J-PLUS Tracking Tool, a web application, has been implemented, which includes tools to plan the best observations, as well as tools to create the command files for the telescope; to track the observations; and to know the status of the survey. In this environment, robustness is an important point. To obtain it, a feedback software system has been implemented. This software automatically decides and marks which observations are valid or which must be repeated. It bases its decision on the data obtained from the data management pipeline database using a complex system of pointing and filter statuses. This contribution presents J-PLUS Tracking Tool and all feedback software system.

Read this paper on arXiv…

T. Civera
Mon, 26 Dec 22
18/39

Comments: 4 pages, 2 figures, to be published in Proc. ADASS XXXII (2022)

Failure type detection and predictive maintenance for the next generation of imaging atmospheric Cherenkov telescopes [IMA]

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http://arxiv.org/abs/2212.12381


The next generation of imaging atmospheric Cherenkov telescopes will be composed of hundreds of telescopes working together to attempt to unveil some fundamental physics of the high-energy Universe. Along with the scientific data, a large volume of housekeeping and auxiliary data coming from weather stations, instrumental sensors, logging files, etc., will be collected as well. Driven by supervised and reinforcement learning algorithms, such data can be exploited for applying predictive maintenance and failure type detection to these astrophysical facilities. In this paper, we present the project aiming to trigger the development of a model that will be able to predict, just in time, forthcoming component failures along with their kind and severity

Read this paper on arXiv…

F. Incardona, A. Costa and K. Munari
Mon, 26 Dec 22
35/39

Comments: N/A

Detecting neutrinos in IceCube with Cherenkov light in the South Pole ice [IMA]

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http://arxiv.org/abs/2212.12142


The IceCube Neutrino Observatory detects GeV-to-PeV+ neutrinos via the Cherenkov light produced by secondary charged particles from neutrino interactions with the South Pole ice. The detector consists of over 5000 spherical Digital Optical Modules (DOM), each deployed with a single downward-facing photomultiplier tube (PMT) and arrayed across 86 strings over a cubic-kilometer. IceCube has measured the astrophysical neutrino flux, searched for their origins, and constrained neutrino oscillation parameters and cross sections. These were made possible by an in-depth characterization of the glacial ice, which has been refined over time, and novel approaches in reconstructions that utilize fast approximations of Cherenkov yield expectations.
After over a decade of nearly continuous IceCube operation, the next generation of neutrino telescopes at the South Pole are taking shape. The IceCube Upgrade will add seven additional strings in a dense infill configuration. Multi-PMT OMs will be attached to each string, along with improved calibration devices and new sensor prototypes. Its denser OM and string spacing will extend sensitivity to lower neutrino energies and further constrain neutrino oscillation parameters. The calibration goals of the Upgrade will help guide the design and construction of IceCube Gen2, which will increase the effective volume by nearly an order of magnitude.

Read this paper on arXiv…

T. Yuan
Mon, 26 Dec 22
38/39

Comments: 5 pages, 5 figures, proceeding from the 11th International Workshop on Ring Imaging Cherenkov Detectors (RICH2022)

NIRCam Performance on JWST In Flight [IMA]

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http://arxiv.org/abs/2212.12069


The Near Infrared Camera for the James Webb Space Telescope is delivering the imagery that astronomers have hoped for ever since JWST was proposed back in the 1990s. In the Commissioning Period that extended from right after launch to early July 2022 NIRCam has been subjected to a number of performance tests and operational checks. The camera is exceeding pre-launch expectations in virtually all areas with very few surprises discovered in flight. NIRCam also delivered the imagery needed by the Wavefront Sensing Team for use in aligning the telescope mirror segments (\citealt{Acton_etal2022}, \citealt{McElwain_etal2022}).

Read this paper on arXiv…

M. Rieke, D. Kelly, K. Misselt, et. al.
Mon, 26 Dec 22
39/39

Comments: 17 pages, 18 figures Accepted for publication in PASP

CubeSats for Gamma-Ray Astronomy [IMA]

Posted on by

http://arxiv.org/abs/2212.11413


After many years of flying in space primarily for educational purposes, CubeSats – tiny satellites with form factors corresponding to arrangements of “1U” units, or cubes, each 10 cm on a side – have come into their own as valuable platforms for technology advancement and scientific investigations. CubeSats offer comparatively rapid, low-cost access to space for payloads that be built, tested, and operated by relatively small teams, with substantial contributions from students and early career researchers. Continuing advances in compact, low-power detectors, readout electronics, and flight computers have now enabled X-ray and gamma-ray sensing payloads that can fit within the constraints of CubeSat missions, permitting in-orbit demonstrations of new techniques and innovative high-energy astronomy observations. Gamma-ray-sensing CubeSats are certain to make an important contribution in the new era of multi-messenger, time-domain astronomy by detecting and localizing bright transients such as gamma-ray bursts, solar flares, and terrestrial gamma-ray flashes; however, other astrophysical science areas requiring long observations in a low-background environment, including gamma-ray polarimetry, studies of nuclear lines, and measurement of diffuse backgrounds, will likely benefit as well. We present the primary benefits of CubeSats for high-energy astronomy, highlight the scientific areas currently or soon to be studied, and review the missions that are currently operating, under development, or proposed. A rich portfolio of CubeSats for gamma-ray astronomy already exists, and the potential for a broad range of creative and scientifically productive missions in the near future is very high.

Read this paper on arXiv…

P. Bloser, D. Murphy, F. Fiore, et. al.
Fri, 23 Dec 22
13/58

Comments: Book chapter for the “Handbook of X-ray and Gamma-ray Astrophysics”, Section “Optics and Detectors for Gamma-ray Astrophysics” (Editors in chief: C. Bambi and A. Santangelo, Springer Singapore). 33 pages, 11 figures

Automatic Spectroscopic Data Reduction using BANZAI [IMA]

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http://arxiv.org/abs/2212.11381


Time domain astronomy has both increased the data volume and the urgency of data reduction in recent years. Spectra provide key insights into astrophysical phenomena but require complex reductions. Las Cumbres Observatory has six spectrographs: two low-dispersion FLOYDS instruments and four NRES high-resolution echelle spectrographs. We present an extension of the data reduction framework, BANZAI, to process spectra automatically, with no human interaction. We also present interactive tools we have developed for human vetting and improvement of the spectroscopic reduction. Tools like those presented here are essential to maximize the scientific yield from current and future time domain astronomy.

Read this paper on arXiv…

C. McCully, M. Daily, G. Brandt, et. al.
Fri, 23 Dec 22
26/58

Comments: 12 pages, 8 figures, SPIE Proceedings 2022

Primary Objective Grating Telescopy: Optical Properties and Feasibility of Applications [IMA]

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http://arxiv.org/abs/2212.11443


We develop the theoretical foundation for primary objective grating (POG) telescopy. In recent years, a wide range of telescope designs that collect the light over a large grating and focus it with a secondary receiving optic that is placed at grazing exodus have been proposed by Thomas D. Ditto, and are sometimes referred to as Dittoscopes. Applications include discovery and characterization of exoplanets, discovery of near-Earth asteroids, and spectroscopic surveys of the sky. These telescopes would have small aerial mass, and therefore provide a path forward to launch large telescopes into space. Because this series of telescope designs departs from traditional telescope designs, it has been difficult to evaluate which applications are most advantageous for this design. Here, we define a new figure of merit, the “modified etendue,” that characterizes the photon collection capability of a POG. It is demonstrated that the diffraction limit for observations is determined by the length of the grating. We evaluate the effects of atmospheric seeing for ground-based applications and the disambiguation of position vs. wavelength in the focal plane using a second dispersing element. Finally, some strategies for fully reaping the benefits of POG optical characteristics are discussed.

Read this paper on arXiv…

L. Swordy, H. Newberg and T. Ditto
Fri, 23 Dec 22
29/58

Comments: 25 pages, 12 figures, submitted to JATIS

The ngEHT Analysis Challenges [IMA]

Posted on by

http://arxiv.org/abs/2212.11355


The next-generation Event Horizon Telescope (ngEHT) will be a significant enhancement of the Event Horizon Telescope (EHT) array, with $\sim 10$ new antennas and instrumental upgrades of existing antennas. The increased $uv$-coverage, sensitivity, and frequency coverage allow a wide range of new science opportunities to be explored. The ngEHT Analysis Challenges have been launched to inform development of the ngEHT array design, science objectives, and analysis pathways. For each challenge, synthetic EHT and ngEHT datasets are generated from theoretical source models and released to the challenge participants, who analyze the datasets using image reconstruction and other methods. The submitted analysis results are evaluated with quantitative metrics. In this work, we report on the first two ngEHT Analysis Challenges. These have focused on static and dynamical models of M87* and Sgr A*, and shown that high-quality movies of the extended jet structure of M87* and near-horizon hourly timescale variability of Sgr A* can be reconstructed by the reference ngEHT array in realistic observing conditions, using current analysis algorithms. We identify areas where there is still room for improvement of these algorithms and analysis strategies. Other science cases and arrays will be explored in future challenges.

Read this paper on arXiv…

F. Roelofs, L. Blackburn, G. Lindahl, et. al.
Fri, 23 Dec 22
37/58

Comments: 32 pages, 14 figures, accepted for publication in Galaxies

Gaia Data Release 3: Gaia scan-angle dependent signals and spurious periods [IMA]

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http://arxiv.org/abs/2212.11971


Context: Gaia DR3 time series data may contain spurious signals related to the time-dependent scan angle. Aims: We aim to explain the origin of scan-angle dependent signals and how they can lead to spurious periods, provide statistics to identify them in the data, and suggest how to deal with them in Gaia DR3 data and in future releases. Methods: Using real Gaia data, alongside numerical and analytical models, we visualise and explain the features observed in the data. Results: We demonstrated with Gaia data that source structure (multiplicity or extendedness) or pollution from close-by bright objects can cause biases in the image parameter determination from which photometric, astrometric and (indirectly) radial velocity time series are derived. These biases are a function of the time-dependent scan direction of the instrument and thus can introduce scan-angle dependent signals, which in turn can result in specific spurious periodic signals. Numerical simulations qualitatively reproduce the general structure observed in the spurious period and spatial distribution of photometry and astrometry. A variety of statistics allows for identification of affected sources. Conclusions: The origin of the scan-angle dependent signals and subsequent spurious periods is well-understood and is in majority caused by fixed-orientation optical pairs with separation <0.5″ (amongst which binaries with P>>5y) and (cores of) distant galaxies. Though the majority of sources with affected derived parameters have been filtered out from the Gaia archive, there remain Gaia DR3 data that should be treated with care (e.g. gaia_source was untouched). Finally, the various statistics discussed in the paper can not only be used to identify and filter affected sources, but alternatively reveal new information about them not available through other means, especially in terms of binarity on sub-arcsecond scale.

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B. Holl, C. Fabricius, J. Portell, et. al.
Fri, 23 Dec 22
46/58

Comments: 60 Figures, 2 Tables, submitted to A&A (v1: first partial revision incorporating various, but not yet all comments from the referee)

PACMAN: A pipeline to reduce and analyze Hubble Wide Field Camera 3 IR Grism data [IMA]

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http://arxiv.org/abs/2212.11421


Here we present PACMAN, an end-to-end pipeline developed to reduce and analyze HST/WFC3 data. The pipeline includes both spectral extraction and light curve fitting. The foundation of PACMAN has been already used in numerous publications (e.g., Kreidberg et al., 2014; Kreidberg et al., 2018) and these papers have already accumulated hundreds of citations. The Hubble Space Telescope (HST) has become the preeminent workhorse facility for the characterization of extrasolar planets. HST currently has two of the most powerful space-based tools for characterizing exoplanets over a broad spectral range: The Space Telescope Imaging Spectrograph (STIS) in the UV and the Wide Field Camera 3 (WFC3) in the Near Infrared. With the introduction of a spatial scan mode on WFC3 where the star moves perpendicular to the dispersion direction during an exposure, WFC3 observations have become very efficient due to the reduction of overhead time and the possibility of longer exposures without saturation. For exoplanet characterization, WFC3 is used for transit and secondary eclipse spectroscopy, and phase curve observations. The instrument has two different grisms: G102 with a spectral range from 800 nm to up to 1150 nm and G141 encompassing 1075 nm to about 1700 nm. The spectral range of WFC3/G141 is primarily sensitive to molecular absorption from water at approximately 1.4 microns. This led to the successful detection of water in the atmosphere of over a dozen of exoplanets. The bluer part of WFC3, the G102 grism, is also sensitive to water and most notably led to the first detection of a helium exosphere.

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S. Zieba and L. Kreidberg
Fri, 23 Dec 22
49/58

Comments: 8 pages, 2 figures, Published in JOSS, GitHub: this https URL

The Gaia AVU-GSR parallel solver: preliminary studies of a LSQR-based application in perspective of exascale systems [IMA]

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http://arxiv.org/abs/2212.11675


The Gaia Astrometric Verification Unit-Global Sphere Reconstruction (AVU-GSR) Parallel Solver aims to find the astrometric parameters for $\sim$10$^8$ stars in the Milky Way, the attitude and the instrumental specifications of the Gaia satellite, and the global parameter $\gamma$ of the post Newtonian formalism. The code iteratively solves a system of linear equations, $\mathbf{A} \times \vec{x} = \vec{b}$, where the coefficient matrix $\mathbf{A}$ is large ($\sim$$10^{11} \times 10^8$ elements) and sparse. To solve this system of equations, the code exploits a hybrid implementation of the iterative PC-LSQR algorithm, where the computation related to different horizontal portions of the coefficient matrix is assigned to separate MPI processes. In the original code, each matrix portion is further parallelized over the OpenMP threads. To further improve the code performance, we ported the application to the GPU, replacing the OpenMP parallelization language with OpenACC. In this port, $\sim$95% of the data is copied from the host to the device at the beginning of the entire cycle of iterations, making the code $compute$ $bound$ rather than $data$$-$$transfer$ $bound$. The OpenACC code presents a speedup of $\sim$1.5 over the OpenMP version but further optimizations are in progress to obtain higher gains. The code runs on multiple GPUs and it was tested on the CINECA supercomputer Marconi100, in anticipation of a port to the pre-exascale system Leonardo, that will be installed at CINECA in 2022.

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V. Cesare, U. Becciani, A. Vecchiato, et. al.
Fri, 23 Dec 22
57/58

Comments: 18 pages, 8 figures, 3 pseudocodes, published in Astronomy and Computing, Volume 41, October 2022, 100660, accepted for publication on 4th October 2022

XMM-Newton [IMA]

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http://arxiv.org/abs/2212.10995


The X-ray Multi-mirror Mission (XMM-Newton) provides simultaneous non-dispersive spectroscopic X-ray imaging and timing, medium resolution dispersive X-ray spectroscopy and optical/UV imaging, spectroscopy and timing. In combination, the imaging cameras offer an effective area over the energy range from 150 eV to 12 keV of up to 2500 cm$^2$ at 1.5 keV and $\sim$1800 cm$^2$ at 5 keV. The gratings cover an energy range from 0.4 keV to 2.2 keV with a combined effective area of up to 120 cm$^2$ at 0.8 keV. XMM-Newton offers unique opportunities for a wide variety of sensitive X-ray observations accompanied by simultaneous optical/UV measurements. The majority of XMM-Newton’s observing time is made available to the astronomical community by peer-reviewed Announcements of Opportunity. The scientific exploitation of XMM-Newton data is aided by an observatory-class X-ray facility which provides analysis software, pipeline processing, calibration and catalogue generation. Around 380 refereed papers based on XMM-Newton data are published each year with a high fraction of papers reporting transformative scientific results.

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N. Schartel, R. González-Riestra, P. Kretschmar, et. al.
Thu, 22 Dec 22
28/59

Comments: 37 pages, 28 figures, Invited chapter for {\it Handbook of X-ray and Gamma-ray Astrophysics} (Eds. C. Bambi and A. Santangelo, Springer Singapore, expected in 2022

Measures of Variance on Windowed Gaussian Processes [IMA]

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http://arxiv.org/abs/2212.10684


The variance and fractional variance on a fixed time window (variously known as “rms percent” or “modulation index”) are commonly used to characterize the variability of astronomical sources. We summarize properties of this statistic for a Gaussian process.

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D. Lee and C. Gammie
Thu, 22 Dec 22
55/59

Comments: 5 pages, 1 figure, submitted to RNAAS

E-TEST prototype design report [IMA]

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http://arxiv.org/abs/2212.10083


E-TEST (Einstein Telescope Euregio-Meuse-Rhin Site and Technology) is a project recently funded by the European program Ineterreg Euregio Meuse-Rhine. This program is dedicated to innovative cross boarder activities between Belgium, The Netherlands and Germany. With a total budget of15MC and a consortium of 11 partners from the three countries, the objective of the project is twofold. Firstly, to develop an eco-friendly and non-invasive imaging of the geological conditions as well as the development of an observatory of the underground in the EMR region. Secondly, to develop technologies necessary for 3rd generation gravitational wave detectors. In particular, it is proposed to develop a prototype of large suspended cryogenic silicon mirror, isolated from seismic vibrations at low frequency. The total budget of the project is equally spread over the two activities. The first activity is not discussed at all in this report. The E-TEST prototype will have some key unique features: a silicon mirror of 100 kg, a radiative cooling strategy (non contact), a low-frequency hybrid isolation stage, cryogenic sensors and electronics, a laser and optics at 2 microns, a low thermal noise coating.

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A. Sider, L. Amez-Droz, A. Amorosi, et. al.
Wed, 21 Dec 22
8/81

Comments: N/A

Galaxy Image Classification using Hierarchical Data Learning with Weighted Sampling and Label Smoothing [IMA]

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http://arxiv.org/abs/2212.10081


With the development of a series of Galaxy sky surveys in recent years, the observations increased rapidly, which makes the research of machine learning methods for galaxy image recognition a hot topic. Available automatic galaxy image recognition researches are plagued by the large differences in similarity between categories, the imbalance of data between different classes, and the discrepancy between the discrete representation of Galaxy classes and the essentially gradual changes from one morphological class to the adjacent class (DDRGC). These limitations have motivated several astronomers and machine learning experts to design projects with improved galaxy image recognition capabilities. Therefore, this paper proposes a novel learning method, “Hierarchical Imbalanced data learning with Weighted sampling and Label smoothing” (HIWL). The HIWL consists of three key techniques respectively dealing with the above-mentioned three problems: (1) Designed a hierarchical galaxy classification model based on an efficient backbone network; (2) Utilized a weighted sampling scheme to deal with the imbalance problem; (3) Adopted a label smoothing technique to alleviate the DDRGC problem. We applied this method to galaxy photometric images from the Galaxy Zoo-The Galaxy Challenge, exploring the recognition of completely round smooth, in between smooth, cigar-shaped, edge-on and spiral. The overall classification accuracy is 96.32\%, and some superiorities of the HIWL are shown based on recall, precision, and F1-Score in comparing with some related works. In addition, we also explored the visualization of the galaxy image features and model attention to understand the foundations of the proposed scheme.

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X. Ma, X. Li, A. Luo, et. al.
Wed, 21 Dec 22
17/81

Comments: accepted by MNRAS

Demonstration of Ultrawideband Polarimetry Using VLBI Exploration of Radio Astrometry (VERA) [IMA]

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http://arxiv.org/abs/2212.10144


We report on recent technical developments in the front- and back-ends for the four 20 m radio telescopes of the Japanese Very-Long-Baseline Interferometry (VLBI) project, VLBI Exploration of Radio Astrometry (VERA). We present a brief overview of a dual-circular polarization receiving and ultrawideband (16 Giga bit s$^{-1}$) recording systems that were installed on each of the four telescopes operating at 22 and 43 GHz bands. The wider-band capability improves the sensitivity of VLBI observations for continuum emission, and the dual-polarization capability enables the study of magnetic fields in relativistic jets ejected from supermassive black holes in active galactic nuclei and in sites of star formation and around evolved stars. We present the linear polarization intensity maps of extragalactic sources at 22 and 43 GHz obtained from the most recent test observations to show the state of the art of the VERA polarimetric observations. At the end of this article, given the realization of VLBI polarimetry with VERA, we describe the future prospects for scientific aims and further technical developments.

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Y. Hagiwara, K. Hada, M. Takamura, et. al.
Wed, 21 Dec 22
23/81

Comments: 14 pages, 7 figures, 3 tables, published in the Special issue ” Challenges in Understanding Black Hole Powered Jets with VLBI”, Galaxies Journal

Cats vs Dogs, Photons vs Hadrons [IMA]

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http://arxiv.org/abs/2212.10281


In gamma ray astronomy with Cherenkov telescopes, machine learning models are needed to guess what kind of particles generated the detected light, and their energies and directions. The focus in this work is on the classification task, training a simple convolutional neural network suitable for binary classification (as it could be a cats vs dogs classification problem), using as input uncleaned images generated by Montecarlo data for a single ASTRI telescope. Results show an enhanced discriminant power with respect to classical random forest methods.

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F. Visconti
Wed, 21 Dec 22
33/81

Comments: 4 pages, 3 figures, 2 tables, to be published in Proceedings of ML4ASTRO conference, Poster category: this https URL

Image enhancement with wavelet-optimized whitening [IMA]

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http://arxiv.org/abs/2212.10134


Due to its physical nature, the solar corona exhibits large spatial variations of intensity that make it difficult to simultaneously visualize the features present at all levels and scales. Many general-purpose and specialized filters have been proposed to enhance coronal images. However, most of them require the ad hoc tweaking of parameters to produce subjectively good results. Our aim was to develop a general purpose image enhancement technique that would produce equally good results, but based on an objective criterion. The underlying principle of the method is the equalization, or whitening, of power in the {\it `a trous} wavelet spectrum of the input image at all scales and locations. An edge-avoiding modification of the {\it `a trous} transform that uses bilateral weighting by the local variance in the wavelet planes is used to suppress the undesirable halos otherwise produced by discontinuities in the data. Results are presented for a variety of extreme ultraviolet (EUV) and white light images of the solar corona. The proposed filter produces sharp and contrasted output, without requiring the manual adjustment of parameters. Furthermore, the built-in denoising scheme prevents the explosion of high-frequency noise typical of other enhancement methods, without smoothing statistically significant small-scale features. The standard version of the algorithm is about two times faster than the widely used multiscale Gaussian normalization (MGN). The bilateral version is slower, but provides significantly better results in the presence of spikes or edges. Comparisons with other methods suggest that the whitening principle may correspond to the subjective criterion of most users when adjusting free parameters.

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F. Auchère, E. Soubrié, G. Pelouze, et. al.
Wed, 21 Dec 22
52/81

Comments: N/A

Spectral performance of the Microchannel X-ray Telescope on board the SVOM mission [IMA]

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http://arxiv.org/abs/2212.09863


The Microchannel X-ray Telescope (MXT) is an innovative compact X-ray instrument on board the SVOM astronomical mission dedicated to the study of transient phenomena such as gamma-ray bursts. During 3 weeks, we have tested the MXT flight model at the Panter X-ray test facility under the nominal temperature and vacuum conditions that MXT will undergo in-flight. We collected data at series of characteristic energies probing the entire MXT energy range, from 0.28 keV up to 9 keV, for multiple source positions with the center of the point spread function (PSF) inside and outside the detector field of view (FOV). We stacked the data of the positions with the PSF outside the FOV to obtain a uniformly illuminated matrix and reduced all data sets using a dedicated pipeline. We determined the best spectral performance of MXT using an optimized data processing, especially for the energy calibration and the charge sharing effect induced by the pixel low energy thresholding. Our results demonstrate that MXT is compliant with the instrument requirement regarding the energy resolution (<80 eV at 1.5 keV), the low and high energy threshold, and the accuracy of the energy calibration ($\pm$20 eV). We also determined the charge transfer inefficiency (~$10^{-5}$) of the detector and modeled its evolution with energy prior to the irradiation that MXT will undergo during its in-orbit lifetime. Finally, we measured the relation of the energy resolution as function of the photon energy. We determined an equivalent noise charge of 4.9 $\pm$ 0.2 e- rms for the MXT detection chain and a Fano factor of 0.131 $\pm$ 0.003 in silicon at 208 K, in agreement with previous works. This campaign confirmed the promising scientific performance that MXT will be able to deliver during the mission lifetime.

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B. Schneider, N. Renault-Tinacci, D. Götz, et. al.
Wed, 21 Dec 22
59/81

Comments: 20 pages, 10 figures, accepted for publication in Experimental Astronomy

A New Period Determination Method for Periodic Variable Stars [IMA]

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http://arxiv.org/abs/2212.10037


Variable stars play a key role in understanding the Milky Way and the universe. The era of astronomical big data presents new challenges for quick identification of interesting and important variable stars. Accurately estimating the periods is the most important step to distinguish different types of variable stars. Here, we propose a new method of determining the variability periods. By combining the statistical parameters of the light curves, the colors of the variables, the window function and the GLS algorithm, the aperiodic variables are excluded and the periodic variables are divided into eclipsing binaries and NEB variables (other types of periodic variable stars other than eclipsing binaries), the periods of the two main types of variables are derived. We construct a random forest classifier based on 241,154 periodic variables from the ASAS-SN and OGLE datasets of variables. The random forest classifier is trained on 17 features, among which 11 are extracted from the light curves and 6 are from the Gaia Early DR3, ALLWISE and 2MASS catalogs. The variables are classified into 7 superclasses and 17 subclasses. In comparison with the ASAS-SN and OGLE catalogs, the classification accuracy is generally above approximately 82% and the period accuracy is 70%-99%. To further test the reliability of the new method and classifier, we compare our results with the results of Chen et al. (2020) for ZTF DR2. The classification accuracy is generally above 70%. The period accuracy of the EW and SR variables is 50% and 53%, respectively. And the period accuracy of other types of variables is 65%-98%.

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X. Xu, Q. Zhu, X. Li, et. al.
Wed, 21 Dec 22
81/81

Comments: 23 pages, 10 figures

Fastcc: fast colour corrections for broadband radio telescope data [IMA]

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http://arxiv.org/abs/2212.09488


Broadband receiver data need colour corrections applying to correct for the different source spectra across their wide bandwidths. The full integration over a receiver bandpass may be computationally expensive and redundant when repeated many times. Colour corrections can be applied, however, using a simple quadratic fit based on the full integration instead. Here we describe fastcc and interpcc, quick Python and IDL codes that return, respectively, colour correction coefficients for different power-law spectral indices and modified black bodies for various Cosmic Microwave Background related experiments. The codes are publicly available, and can be easily extended to support additional telescopes.

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M. Peel, R. Genova-Santos, C. Dickinson, et. al.
Tue, 20 Dec 22
4/97

Comments: 3 pages, 1 figure. Published in RNAAS

Direct D-atom incorporation in radicals: An overlooked pathway for deuterium fractionation [IMA]

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http://arxiv.org/abs/2212.08680


Direct D-H exchange in radicals is investigated in a quasi-uniform flow employing chirped pulse mm-wave spectroscopy. Inspired by the H-atom catalyzed isomerization of C3H2 reported in our previous study, D atom reactions with the propargyl (C3H3) radical and its photoproducts were investigated. We observed very efficient D atom enrichment in the photoproducts through an analogous process of D addition/H elimination to C3H2 isomers occurring at 40K or below. Cyclic C3HD is the only deuterated isomer observed, consistent with the expected addition/elimination yielding the lowest energy product. The other expected addition/elimination product, deuterated propargyl, is not directly detected, although its presence is inferred by the observations in the latter part of the flow. There, in the high-density region of the flow, we observed both isotopomers of singly deuterated propyne attributed to stabilization of the H + C3H2D or D + C3H3 adducts. The implications of these observations for the deuterium fractionation of hydrocarbon radicals in astrochemical environments is discussed with the support of a monodeuterated chemical kinetic model.

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N. Dias, R. Gurusinghe, B. Broderick, et. al.
Tue, 20 Dec 22
24/97

Comments: N/A

Data mining techniques on astronomical spectra data. II : Classification Analysis [IMA]

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http://arxiv.org/abs/2212.09286


Classification is valuable and necessary in spectral analysis, especially for data-driven mining. Along with the rapid development of spectral surveys, a variety of classification techniques have been successfully applied to astronomical data processing. However, it is difficult to select an appropriate classification method in practical scenarios due to the different algorithmic ideas and data characteristics. Here, we present the second work in the data mining series – a review of spectral classification techniques. This work also consists of three parts: a systematic overview of current literature, experimental analyses of commonly used classification algorithms and source codes used in this paper. Firstly, we carefully investigate the current classification methods in astronomical literature and organize these methods into ten types based on their algorithmic ideas. For each type of algorithm, the analysis is organized from the following three perspectives. (1) their current applications and usage frequencies in spectral classification are summarized; (2) their basic ideas are introduced and preliminarily analysed; (3) the advantages and caveats of each type of algorithm are discussed. Secondly, the classification performance of different algorithms on the unified data sets is analysed. Experimental data are selected from the LAMOST survey and SDSS survey. Six groups of spectral data sets are designed from data characteristics, data qualities and data volumes to examine the performance of these algorithms. Then the scores of nine basic algorithms are shown and discussed in the experimental analysis. Finally, nine basic algorithms source codes written in python and manuals for usage and improvement are provided.

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H. Yang, L. Zhou, J. Cai, et. al.
Tue, 20 Dec 22
26/97

Comments: 25 pages, 41 figures

Eliminating polarization leakage effect for neutral hydrogen intensity mapping with deep learning [IMA]

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http://arxiv.org/abs/2212.08773


The neutral hydrogen (HI) intensity mapping (IM) survey is regarded as a promising approach for cosmic large-scale structure (LSS) studies. A major issue for the HI IM survey is to remove the bright foreground contamination. A key to successfully remove the bright foreground is to well control or eliminate the instrumental effects. In this work, we consider the instrumental effect of polarization leakage and use the U-Net approach, a deep learning-based foreground removal technique, to eliminate the polarization leakage effect.In this method, the principal component analysis (PCA) foreground subtraction is used as a preprocessing step for the U-Net foreground subtraction. Our results show that the additional U-Net processing could either remove the foreground residual after the conservative PCA subtraction or compensate for the signal loss caused by the aggressive PCA preprocessing. Finally, we test the robustness of the U-Net foreground subtraction technique and show that it is still reliable in the case of existing constraint error on HI fluctuation amplitude.

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L. Gao, Y. Li, S. Ni, et. al.
Tue, 20 Dec 22
32/97

Comments: 12 pages, 11 figures

Skyglow inside your eyes: intraocular scattering and artificial brightness of the night sky [IMA]

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http://arxiv.org/abs/2212.09103


The visual perception of the natural night sky in many places of the world is strongly disturbed by anthropogenic light. Part of this artificial light is scattered in the atmosphere and propagates towards the observer, adding to the natural brightness and producing a light polluted sky. However, atmospheric scattering is not the only mechanism contributing to increase the visual skyglow. The rich and diverse biological media forming the human eye also scatter light very efficiently and contribute, in some cases to a big extent, to the total sky brightness detected by the retinal photoreceptors. In this paper we quantify this effect and assess its relevance when the eye pupil is illuminated by light sources within the visual field. Our results show that intraocular scattering constitutes a significant part of the perceived sky brightness at short distances from streetlights. These results provide quantitative support to the everyday experience that substantial gains in naked-eye star limiting magnitudes can be achieved by blocking the direct light from the lamps that reaches the eye pupil.

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S. Bará and C. Bao-Varela
Tue, 20 Dec 22
48/97

Comments: 9 pages, 5 figures

Ultra-Low-Frequency Radio Astronomy Observations from a Selenocentric Orbit: first results of the Longjiang-2 experiment [IMA]

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http://arxiv.org/abs/2212.09590


This paper introduces the first results of observations with the Ultra-Long-Wavelength (ULW) — Low Frequency Interferometer and Spectrometer (LFIS) on board the selenocentric satellite Longjiang-2. We present a brief description of the satellite and focus on the LFIS payload. The in-orbit commissioning confirmed a reliable operational status of the instrumentation. We also present results of a transition observation, which offers unique measurements on several novel aspects. We estimate the RFI suppression required for such a radio astronomy instrumentation at the Moon distances from Earth to be of the order of 80 dB. We analyse a method of separating Earth- and satellite-originated radio frequency interference (RFI). It is found that the RFI level at frequencies lower than a few MHz is smaller than the receiver noise floor.

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J. Yan, J. Wu, L. Gurvits, et. al.
Tue, 20 Dec 22
49/97

Comments: Accepted for publication in Experimental Astronomy; 22 pages, 11 figures

Applications of the source-frequency phase-referencing technique for ngEHT observations [IMA]

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http://arxiv.org/abs/2212.08994


The source-frequency phase-referencing (SFPR) technique has been demonstrated to have great advantages for mm-VLBI observations. By implementing simultaneous multi-frequency receiving systems on the next generation Event Horizon Telescope (ngEHT) antennas, it is feasible to carry out a frequency phase transfer (FPT) which could calibrate the non-dispersive propagation errors and significantly increase the phase coherence in the visibility data. Such increase offers an efficient approach for weak source or structure detection. SFPR also makes it possible for high precision astrometry, including the core-shift measurements up to sub-mm wavelengths for Sgr A* and M87* etc. We also briefly discuss the technical and scheduling considerations for future SFPR observations with the ngEHT.

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W. Jiang, G. Zhao, Z. Shen, et. al.
Tue, 20 Dec 22
63/97

Comments: 9 pages, in the special issue for ngEHT

A study on Performance Boost of a 17~m class Cherenkov telescope with a SiPM-based camera [IMA]

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http://arxiv.org/abs/2212.09456


The current generation of Imaging Atmospheric Cherenkov Telescopes (IACTs), comprised of major installations such as the MAGIC telescopes, H.E.S.S. and VERITAS, is classified as the 3$^{\mathrm{rd}}$ generation of suchs instruments. These telescopes use multipixel cameras composed of thousands of photomultiplier tubes (PMTs). The total light throughput of such instruments depends, besides the PMT photon detection efficiency (PDE), on the mirror dish reflectivity, and the light absorption by the camera window. The supremacy of PMTs is currently being challenged by photon sensors rapidly spreading in popularity, the silicon photomultipliers (SiPMs), that are becoming a valid alternative thanks to their high PDE, low operating voltage and flexibility in installation. In this report, we investigate the performance of an existing 3$^{\mathrm{rd}}$-generation IACT array (taking as an example MAGIC) in which PMTs would be replaced with SiPMs, with minimal further hardware intervention. This would mean that other systems of the telescope responsible for the light collection, in particular the optics, would remain the same, and only the electronic to steer the different photodetectors would be modified. We find an increase of sensitivity up to a factor of 2 for energies below 200~GeV. Interestingly, we also find that the stronger sensitivity of SiPMs in the red part of the spectrum, a source of background for IACTs, does not affect this conclusion.

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C. Arcaro, M. Doro, J. Sitarek, et. al.
Tue, 20 Dec 22
66/97

Comments: N/A

Reversible time-step adaptation for the integration of few-body systems [IMA]

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http://arxiv.org/abs/2212.09745


The time step criterion plays a crucial role in direct N-body codes. If not chosen carefully, it will cause a secular drift in the energy error. Shared, adaptive time step criteria commonly adopt the minimum pairwise time step, which suffers from discontinuities in the time evolution of the time step. This has a large impact on the functioning of time step symmetrisation algorithms. We provide new demonstrations of previous findings that a smooth and weighted average over all pairwise time steps in the N-body system, improves the level of energy conservation. Furthermore, we compare the performance of 27 different time step criteria, by considering 3 methods for weighting time steps and 9 symmetrisation methods. We present performance tests for strongly chaotic few-body systems, including unstable triples, giant planets in a resonant chain, and the current Solar System. We find that the harmonic symmetrisation methods (methods A3 and B3 in our notation) are the most robust, in the sense that the symmetrised time step remains close to the time step function. Furthermore, based on our Solar System experiment, we find that our new weighting method based on direct pairwise averaging (method W2 in our notation), is slightly preferred over the other methods.

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T. Boekholt, T. Vaillant and A. Correia
Tue, 20 Dec 22
82/97

Comments: Accepted by MNRAS. 13 pages, 6 figures

Exploring the Universe via the Wide, Deep Near-infrared Imaging ESO Public Survey SHARKS [IMA]

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http://arxiv.org/abs/2212.09471


The ESO Public Survey Southern H-ATLAS Regions Ks-band Survey (SHARKS) comprises 300 square degrees of deep imaging at 2.2 microns (the Ks band) with the VISTA InfraRed CAMera (VIRCAM) at the 4-metre Visible and Infrared Survey Telescope for Astronomy (VISTA). The first data release of the survey, comprising 5% of the data, was published via the ESO database on 31 January 2022. We describe the strategy and status of the first data release and present the data products. We discuss briefly different scientific areas being explored with the SHARKS data and conclude with an outline of planned data releases.

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H. Dannerbauer, A. Carnero, N. Cross, et. al.
Tue, 20 Dec 22
83/97

Comments: Published in the ESO messenger #187: this https URL

Data mining techniques on astronomical spectra data. I : Clustering Analysis [IMA]

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http://arxiv.org/abs/2212.08419


Clustering is an effective tool for astronomical spectral analysis, to mine clustering patterns among data. With the implementation of large sky surveys, many clustering methods have been applied to tackle spectroscopic and photometric data effectively and automatically. Meanwhile, the performance of clustering methods under different data characteristics varies greatly. With the aim of summarizing astronomical spectral clustering algorithms and laying the foundation for further research, this work gives a review of clustering methods applied to astronomical spectra data in three parts. First, many clustering methods for astronomical spectra are investigated and analysed theoretically, looking at algorithmic ideas, applications, and features. Secondly, experiments are carried out on unified datasets constructed using three criteria (spectra data type, spectra quality, and data volume) to compare the performance of typical algorithms; spectra data are selected from the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) survey and Sloan Digital Sky Survey (SDSS). Finally, source codes of the comparison clustering algorithms and manuals for usage and improvement are provided on GitHub.

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H. Yang, C. Shi, J. Cai, et. al.
Mon, 19 Dec 22
5/62

Comments: 28 pages, 53 figures

Global Extinction: Combined Gemini North and South GMOS Photometry Relative to the Gaia Catalog, and Long-Term Atmospheric Change [IMA]

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http://arxiv.org/abs/2212.08093


Effects of long-term atmospheric change were looked for in photometry employing the Gemini North and South twin Multi-Object Spectrograph (GMOS-N and GMOS-S) archival data. The whole GMOS imaging database, beginning from 2003, was compared against the all-sky Gaia object catalog, yielding ~10^6 Sloan r’-filter samples, ending in 2021. These were combined with reported sky and meteorological conditions, versus a simple model of the atmosphere plus cloud together with simulated throughputs. One exceptionally extincted episode in 2009 is seen, as is a trend (similar at both sites) of about 2 mmag worsening attenuation per decade. This is consistent with solar-radiance transmissivity records going back over six decades, aerosol density measurements, and more than 0.2 deg C per decade rise in global air temperature, which has implications for calibration of historic datasets or future surveys.

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E. Steinbring
Mon, 19 Dec 22
9/62

Comments: 12 pages, 13 figures, to appear in PASP

Temperature dependence of radiation damage annealing of Silicon Photomultipliers [IMA]

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http://arxiv.org/abs/2212.08474


The last decade has increasingly seen the use of silicon photomultipliers (SiPMs) instead of photomultiplier tubes (PMTs). This is due to various advantages of the former on the latter like its smaller size, lower operating voltage, higher detection efficiency, insensitivity to magnetic fields and mechanical robustness to launch vibrations. All these features make SiPMs ideal for use on space based experiments where the detectors require to be compact, lightweight and capable of surviving launch conditions. A downside with the use of this novel type of detector in space conditions is its susceptibility to radiation damage. In order to understand the lifetime of SiPMs in space, both the damage sustained due to radiation as well as the subsequent recovery, or annealing, from this damage have to be studied. Here we present these studies for three different types of SiPMs from the Hamamatsu S13360 series. Both their behaviour after sustaining radiation equivalent to 2 years in low earth orbit in a typical mission is presented, as well as the recovery of these detectors while stored in different conditions. The storage conditions varied in temperature as well as in operating voltage. The study found that the annealing depends significantly on the temperature of the detectors with those stored at high temperatures recovering significantly faster and at recovering closer to the original performance. Additionally, no significant effect from a reasonable bias voltage on the annealing was observed. Finally the annealing rate as a function of temperature is presented along with various operating strategies for the future SiPM based astrophysical detector POLAR-2 as well as for future SiPM based space borne missions.

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N. Angelis, M. Kole, F. Cadoux, et. al.
Mon, 19 Dec 22
27/62

Comments: 33 pages, 24 figures

Micro-arcsecond Astrometry Technology: Detector and Field Distortion Calibration [IMA]

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http://arxiv.org/abs/2212.08129


Microarcsecond (uas) astrometry provides an indispensable way to survey earth-like exoplanets and fully characterize the orbits and masses for assessing their habitability. Highly accurate astrometric measurements can also probe the nature of dark matter, the primordial universe, black holes, and neutron stars for new astrophysics. This paper presents technology for calibrating array detectors and field distortions to achieve narrow field uas astrometry using a 6 m telescope with a focal plane array detector.

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M. Shao, C. Zhai, B. Nemati, et. al.
Mon, 19 Dec 22
29/62

Comments: 16 pages, 10 figures, to be submitted to PASP

Morphological Classification of Radio Galaxies with wGAN-supported Augmentation [IMA]

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http://arxiv.org/abs/2212.08504


Machine learning techniques that perform morphological classification of astronomical sources often suffer from a scarcity of labelled training data. Here, we focus on the case of supervised deep learning models for the morphological classification of radio galaxies, which is particularly topical for the forthcoming large radio surveys. We demonstrate the use of generative models, specifically Wasserstein GANs (wGANs), to generate data for different classes of radio galaxies. Further, we study the impact of augmenting the training data with images from our wGAN on three different classification architectures. We find that this technique makes it possible to improve models for the morphological classification of radio galaxies. A simple Fully Connected Neural Network (FCN) benefits most from including generated images into the training set, with a considerable improvement of its classification accuracy. In addition, we find it is more difficult to improve complex classifiers. The classification performance of a Convolutional Neural Network (CNN) can be improved slightly. However, this is not the case for a Vision Transformer (ViT).

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L. Rustige, J. Kummer, F. Griese, et. al.
Mon, 19 Dec 22
43/62

Comments: 12 pages, 7+2 figures, 1+2 tables. Submitted, comments welcome

Modeling Results and Baseline Design for an RF-SoC-Based Readout System for Microwave Kinetic Inductance Detectors [IMA]

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http://arxiv.org/abs/2212.07938


Building upon existing signal processing techniques and open-source software, this paper presents a baseline design for an RF System-on-Chip Frequency Division Multiplexed readout for a spatio-spectral focal plane instrument based on low temperature detectors. A trade-off analysis of different FPGA carrier boards is presented in an attempt to find an optimum next-generation solution for reading out larger arrays of Microwave Kinetic Inductance Detectors (MKIDs). The ZCU111 RF SoC FPGA board from Xilinx was selected, and it is shown how this integrated system promises to increase the number of pixels that can be read out (per board) which enables a reduction in the readout cost per pixel, the mass and volume, and power consumption, all of which are important in making MKID instruments more feasible for both ground-based and space-based astrophysics. The on-chip logic capacity is shown to form a primary constraint on the number of MKIDs which can be read, channelised, and processed with this new system. As such, novel signal processing techniques are analysed, including Digitally Down Converted (DDC)-corrected sub-maximally decimated sampling, in an effort to reduce logic requirements without compromising signal to noise ratio. It is also shown how combining the ZCU111 board with a secondary FPGA board will allow all 8 ADCs and 8 DACs to be utilised, providing enough bandwidth to read up to 8,000 MKIDs per board-set, an eight-fold improvement over the state-of-the-art, and important in pursuing 100,000 pixel arrays. Finally, the feasibility of extending the operational frequency range of MKIDs to the 5 – 10 GHz regime (or possibly beyond) is investigated, and some benefits and consequences of doing so are presented.

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C. Bracken, E. Baldwin, G. Ulbricht, et. al.
Fri, 16 Dec 22
14/72

Comments: N/A

A guiding center implementation for relativistic particle dynamics in the PLUTO code [IMA]

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http://arxiv.org/abs/2212.08064


We present a numerical implementation of the guiding center approximation to describe the relativistic motion of charged test particles in the PLUTO code for astrophysical plasma dynamics. The guiding center approximation (GCA) removes the time step constraint due to particle gyration around magnetic field lines by following the particle center of motion rather than its full trajectory. The gyration can be detached from the guiding center motion if electromagnetic fields vary sufficiently slow compared to the particle gyration radius and period. Our implementation employs a variable step-size linear multistep method, more efficient when compared to traditional one-step Runge Kutta schemes. A number of numerical benchmarks is presented in order to assess the validity of our implementation.

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A. Mignone, H. Haudemand and E. Puzzoni
Fri, 16 Dec 22
42/72

Comments: N/A

Fast-Cadence High-Contrast Imaging with Information Field Theory [IMA]

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http://arxiv.org/abs/2212.07714


Although many exoplanets have been indirectly detected over the last years, direct imaging of them with ground-based telescopes remains challenging. In the presence of atmospheric fluctuations, it is ambitious to resolve the high brightness contrasts at the small angular separation between the star and its potential partners. Post-processing of telescope images has become an essential tool to improve the resolvable contrast ratios. This paper contributes a post-processing algorithm for fast-cadence imaging, which deconvolves sequences of telescopes images. The algorithm infers a Bayesian estimate of the astronomical object as well as the atmospheric optical path length, including its spatial and temporal structures. For this, we utilize physics-inspired models for the object, the atmosphere, and the telescope. The algorithm is computationally expensive but allows to resolve high contrast ratios despite short observation times and no field rotation. We test the performance of the algorithm with point-like companions synthetically injected into a real data set acquired with the SHARK-VIS pathfinder instrument at the LBT telescope. Sources with brightness ratios down to $6\cdot10^{-4}$ to the star are detected at $185$ mas separation with a short observation time of $0.6\,\text{s}$.

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J. Roth, G. Causi, V. Testa, et. al.
Fri, 16 Dec 22
56/72

Comments: 12 pages, 6 figures

25,000 optical fiber positioning robots for next-generation cosmology [IMA]

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http://arxiv.org/abs/2212.07908


Massively parallel multi-object spectrographs are on the leading edge of cosmology instrumentation. The highly successful Dark Energy Spectroscopic Instrument (DESI) which begun survey operations in May 2021, for example, has 5,000 robotically-actuated multimode fibers, which deliver light from thousands of individual galaxies and quasars simultaneously to an array of high-resolution spectrographs off-telescope. The redshifts are individually measured, thus providing 3D maps of the Universe in unprecedented detail, and enabling precise measurement of dark energy expansion and other key cosmological parameters. Here we present new work in the design and prototyping of the next generation of fiber-positioning robots. At 6.2 mm center-to-center pitch, with 1-2 um positioning precision, and in a scalable form factor, these devices will enable the next generation of cosmology instruments, scaling up to instruments with 10,000 to 25,000 fiber robots.

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J. Silber, D. Schlegel, R. Araujo, et. al.
Fri, 16 Dec 22
66/72

Comments: 6 pages, 8 figures, presented at conference Thirty-Seventh Annual Meeting of The American Society for Precision Engineering, 2022-10-14

Trends in Planetary Science research in the Puna and Atacama desert regions: under-representation of local scientific institutions? [IMA]

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http://arxiv.org/abs/2212.07863


In 2019 while launching a multidisciplinary research project aimed at developing the Puna de Atacama region as a natural laboratory, investigators within the University of Atacama (Chile) conducted a bibliographic search identifying previously studied geographical points of the region and of potential interest for planetary science and astrobiology research. This preliminary work highlighted a significant absence in foreign publications consideration of local institutional involvement. In light of this, a follow-up study was carried out to confirm or refute these first impressions, by comparing the search in two bibliographic databases: Web of Science and Scopus. The results show that almost 60% of the publications based directly on data from the Puna, the Altiplano or the Atacama Desert with objectives related to planetary science or astrobiology do not include any local institutional partner (Argentina, Bolivia, Chile and Peru). Indeed, and beyond the ethical questioning of international collaborations, Latin-American planetary science deserve a strategic structuring, networking, as well as a road map at a national and continental scale, not only to enhance research, development and innovation but also to protect an exceptional natural heritage sampling extreme environmental niches on Earth. Examples of successful international collaborations such as the field of meteorites, terrestrial analogues and space exploration in Chile or astrobiology in Mexico are given as illustrations and possible directions to follow in order to develop planetary sciences in South America.

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A. Tavernier, G. Pinto, M. Valenzuela, et. al.
Fri, 16 Dec 22
72/72

Comments: N/A

GALLIFRAY — A geometric modeling and parameter estimation framework for black hole images using bayesian techniques [IMA]

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http://arxiv.org/abs/2212.06827


Recent observations of the galactic centers of M87 and the Milky Way with the Event Horizon Telescope have ushered in a new era of black hole based tests of fundamental physics using very long baseline interferometry (VLBI). Being a nascent field, there are several different modeling and analysis approaches in vogue (e.g., geometric and physical models, visibility and closure amplitudes, agnostic and multimessenger priors). We present \texttt{GALLIFRAY}, an open-source Python-based framework for estimation/extraction of parameters using VLBI data. It is developed with modularity, efficiency, and adaptability as the primary objectives. This article outlines the design and usage of \texttt{GALLIFRAY}. As an illustration, we fit a geometric and a physical model to simulated datasets using markov chain monte carlo sampling and find good convergence of the posterior distribution. We conclude with an outline of further enhancements currently in development.

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S. Saurabh and S. Nampalliwar
Thu, 15 Dec 22
62/75

Comments: 10 pages, 5 figures. Comments are welcome!

Comparison of dynamical and kinematic reference frames via pulsar positions from timing, Gaia, and interferometric astrometry [IMA]

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http://arxiv.org/abs/2212.07178


Pulsars are special objects whose positions can be determined independently from timing, radio interferometric, and Gaia astrometry at sub-milliarcsecond (mas) precision; thus, they provide a unique way to monitor the link between dynamical and kinematic reference frames. We aimed to assess the orientation consistency between the dynamical reference frame represented by the planetary ephemeris and the kinematic reference frames constructed by Gaia and VLBI through pulsar positions. We identified 49 pulsars in Gaia Data Release 3 and 62 pulsars with very long baseline interferometry (VLBI) positions from the PSR$\pi$ and MSPSR$\pi$ projects and searched for the published timing solutions of these pulsars. We then compared pulsar positions measured by timing, VLBI, and Gaia to estimate the orientation offsets of the ephemeris frames with respect to the Gaia and VLBI reference frames by iterative fitting. We found orientation offsets of $\sim$10 mas in the DE200 frame with respect to the Gaia and VLBI frame. Our results depend strongly on the subset used in the comparison and could be biased by underestimated errors in the archival timing data, reflecting the limitation of using the literature timing solutions to determine the frame rotation.

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N. Liu, Z. Zhu, J. Antoniadis, et. al.
Thu, 15 Dec 22
63/75

Comments: 22 pages, 15 figures, 3 tables, accepted for publication at A&A

A Near-Infrared Pyramid Wavefront Sensor for the MMT [IMA]

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http://arxiv.org/abs/2212.06904


The MMTO Adaptive optics exoPlanet characterization System (MAPS) is an ongoing upgrade to the 6.5-meter MMT Observatory on Mount Hopkins in Arizona. MAPS includes an upgraded adaptive secondary mirror (ASM), upgrades to the ARIES spectrograph, and a new AO system containing both an optical and near-infrared (NIR; 0.9-1.8 um) pyramid wavefront sensor (PyWFS). The NIR PyWFS will utilize an IR-optimized double pyramid coupled with a SAPHIRA detector: a low-read noise electron Avalanche Photodiode (eAPD) array. This NIR PyWFS will improve MAPS’s sky coverage by an order of magnitude by allowing redder guide stars (e.g. K & M-dwarfs or highly obscured stars in the Galactic plane) to be used. To date, the custom designed cryogenic SAPHIRA camera has been fully characterized and can reach sub-electron read noise at high avalanche gain. In order to test the performance of the camera in a closed-loop environment prior to delivery to the observatory, an AO testbed was designed and constructed. In addition to testing the SAPHIRA’s performance, the testbed will be used to test and further develop the proposed on-sky calibration procedure for MMTO’s ASM. We will report on the anticipated performance improvements from our NIR PyWFS, the SAPHIRA’s closed-loop performance on our testbed, and the status of our ASM calibration procedure.

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J. Taylor, S. Sivanandam, N. Anugu, et. al.
Thu, 15 Dec 22
71/75

Comments: SPIE Proceedings, Astronomical Telescopes and Instrumentation, July 2022, 10 pages, 8 figures

Overview of the Observing System and Initial Scientific Accomplishments of the East Asian VLBI Network (EAVN) [IMA]

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http://arxiv.org/abs/2212.07040


The East Asian VLBI Network (EAVN) is an international VLBI facility in East Asia and is operated under mutual collaboration between East Asian countries, as well as part of Southeast Asian and European countries. EAVN currently consists of 16 radio telescopes and three correlators located in China, Japan, and Korea, and is operated mainly at three frequency bands, 6.7, 22, and 43 GHz with the longest baseline length of 5078 km, resulting in the highest angular resolution of 0.28 milliarcseconds at 43 GHz. One of distinct capabilities of EAVN is multi-frequency simultaneous data reception at nine telescopes, which enable us to employ the frequency phase transfer technique to obtain better sensitivity at higher observing frequencies. EAVN started its open-use program in the second half of 2018, providing a total observing time of more than 1100 hours in a year. EAVN fills geographical gap in global VLBI array, resulting in enabling us to conduct contiguous high-resolution VLBI observations. EAVN has produced various scientific accomplishments especially in observations toward active galactic nuclei, evolved stars, and star-forming regions. These activities motivate us to initiate launch of the ‘Global VLBI Alliance’ to provide an opportunity of VLBI observation with the longest baselines on the earth.

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K. Akiyama, J. Algaba, T. An, et. al.
Thu, 15 Dec 22
75/75

Comments: 27 pages, appeared in Galaxies special issue ‘Challenges in Understanding Black Hole Powered Jets with VLBI’ as an invited review

Millimeter/submillimeter VLBI with a Next Generation Large Radio Telescope in the Atacama Desert [IMA]

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http://arxiv.org/abs/2212.05118


The proposed next generation Event Horizon Telescope (ngEHT) concept envisions the imaging of various astronomical sources on scales of microarcseconds in unprecedented detail with at least two orders of magnitude improvement in the image dynamic ranges by extending the Event Horizon Telescope (EHT). A key technical component of ngEHT is the utilization of large aperture telescopes to anchor the entire array, allowing the connection of less sensitive stations through highly sensitive fringe detections to form a dense network across the planet. Here, we introduce two projects for planned next generation large radio telescopes in the 2030s on the Chajnantor Plateau in the Atacama desert in northern Chile, the Large Submillimeter Telescope (LST) and the Atacama Large Aperture Submillimeter Telescope (AtLAST). Both are designed to have a 50-meter diameter and operate at the planned ngEHT frequency bands of 86, 230 and 345\,GHz. A large aperture of 50\,m that is co-located with two existing EHT stations, the Atacama Large Millimeter/Submillimeter Array (ALMA) and the Atacama Pathfinder Experiment (APEX) Telescope in the excellent observing site of the Chajnantor Plateau, will offer excellent capabilities for highly sensitive, multi-frequency, and time-agile millimeter very long baseline interferometry (VLBI) observations with accurate data calibration relevant to key science cases of ngEHT. In addition to ngEHT, its unique location in Chile will substantially improve angular resolutions of the planned Next Generation Very Large Array in North America or any future global millimeter VLBI arrays if combined. LST and AtLAST will be a key element enabling transformative science cases with next-generation millimeter/submillimeter VLBI arrays.

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K. Akiyama, J. Kauffmann, L. Matthews, et. al.
Tue, 13 Dec 22
3/105

Comments: 8 pages, 1 figure, submitted to the special issue of Galaxies “From Vision to Instrument: Creating a Next-Generation Event Horizon Telescope for a New Era of Black Hole Science” as a ngEHT white paper

Target Detection Framework for Lobster Eye X-Ray Telescopes with Machine Learning Algorithms [IMA]

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http://arxiv.org/abs/2212.05497


Lobster eye telescopes are ideal monitors to detect X-ray transients, because they could observe celestial objects over a wide field of view in X-ray band. However, images obtained by lobster eye telescopes are modified by their unique point spread functions, making it hard to design a high efficiency target detection algorithm. In this paper, we integrate several machine learning algorithms to build a target detection framework for data obtained by lobster eye telescopes. Our framework would firstly generate two 2D images with different pixel scales according to positions of photons on the detector. Then an algorithm based on morphological operations and two neural networks would be used to detect candidates of celestial objects with different flux from these 2D images. At last, a random forest algorithm will be used to pick up final detection results from candidates obtained by previous steps. Tested with simulated data of the Wide-field X-ray Telescope onboard the Einstein Probe, our detection framework could achieve over 94% purity and over 90% completeness for targets with flux more than 3 mCrab (9.6 * 10-11 erg/cm2/s) and more than 94% purity and moderate completeness for targets with lower flux at acceptable time cost. The framework proposed in this paper could be used as references for data processing methods developed for other lobster eye X-ray telescopes.

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P. Jia, W. Liu, Y. Liu, et. al.
Tue, 13 Dec 22
48/105

Comments: Accepted by the APJS Journal. Full source code could be downloaded from the China VO with DOI of this https URL Docker version of the code could be obtained under request to the corresponding author

SIPGI: an interactive pipeline for spectroscopic data reduction [IMA]

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http://arxiv.org/abs/2212.05580


SIPGI is a spectroscopic pipeline for the data reduction of optical/near-infrared data acquired by slit-based spectrographs. SIPGI is a complete spectroscopic data reduction environment retaining the high level of flexibility and accuracy typical of the standard “by-hand” reduction methods but with a significantly higher level of efficiency. This is obtained exploiting three main concepts: 1) a built-in data organiser to classify the data, together with a graphical interface; 2) the instrument model (analytic description of the main calibration relations); 3) the design and flexibility of the reduction recipes: the number of tasks required to perform a complete reduction is minimised, preserving the possibility to verify the accuracy of the main stages of data-reduction process. The current version of SIPGI manages data from the MODS and LUCI spectrographs mounted at the Large Binocular Telescope (LBT) with the idea to extend SIPGI to support other through-slit spectrographs.

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S. Bisogni, A. Gargiulo, M. Fumana, et. al.
Tue, 13 Dec 22
78/105

Comments: 4 pages, 3 figure, to appear in proceedings of the Astronomical Data Analysis Software and Systems (ADASS) XXXII, virtual conference held 31 October – 4 November 2022

Photometric calibration in u-band using blue halo stars [IMA]

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http://arxiv.org/abs/2212.05135


We develop a method to calibrate u-band photometry based on the observed color of blue galactic halo stars. The galactic halo stars belong to an old stellar population of the Milky Way and have relatively low metallicity. The “blue tip” of the halo population — the main sequence turn-off (MSTO) stars — is known to have a relatively uniform intrinsic edge u-g color with only slow spatial variation. In SDSS data, the observed variation is correlated with galactic latitude, which we attribute to contamination by higher-metallicity disk stars and fit with an empirical curve. This curve can then be used to calibrate u-band imaging if g-band imaging of matching depth is available. Our approach can be applied to single-field observations at $|b| > 30^\circ$, and removes the need for standard star observations or overlap with calibrated u-band imaging. We include in our method the calibration of g-band data with ATLAS-Refcat2. We test our approach on stars in KiDS DR 4, ATLAS DR 4, and DECam imaging from the NOIRLab Source Catalog (NSC DR2), and compare our calibration with SDSS. For this process, we use synthetic magnitudes to derive the color equations between these datasets, in order to improve zero-point accuracy. We find an improvement for all datasets, reaching a zero-point precision of 0.016 mag for KiDS (compared to the original 0.033 mag), 0.020 mag for ATLAS (originally 0.027 mag), and 0.016 mag for DECam (originally 0.041 mag). Thus, this method alone reaches the goal of 0.02 mag photometric precision in u-band for the Rubin Observatory’s Legacy Survey of Space and Time (LSST).

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S. Liang and A. Linden
Tue, 13 Dec 22
90/105

Comments: Accepted for publication in MNRAS

pyTANSPEC: A Data Reduction Package for TANSPEC [IMA]

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http://arxiv.org/abs/2212.04815


The TIFR-ARIES Near Infrared Spectrometer (TANSPEC) instrument provides simultaneous wavelength coverage from 0.55 to 2.5 micron, mounted on India’s largest ground-based telescope, 3.6-m Devasthal Optical Telescope at Nainital, India. The TANSPEC offers three modes of observations, imaging with various filters, spectroscopy in the low-resolution prism mode with derived R~ 100-400 and the high-resolution cross-dispersed mode (XD-mode) with derived median R~ 2750 for a slit of width 0.5 arcsec. In the XD-mode, ten cross-dispersed orders are packed in the 2048 x 2048 pixels detector to cover the full wavelength regime. As the XD-mode is most utilized as well as for consistent data reduction for all orders and to reduce data reduction time, a dedicated pipeline is at the need. In this paper, we present the code for the TANSPEC XD-mode data reduction, its workflow, input/output files, and a showcase of its implementation on a particular dataset. This publicly available pipeline pyTANSPEC is fully developed in Python and includes nominal human intervention only for the quality assurance of the reduced data. Two customized configuration files are used to guide the data reduction. The pipeline creates a log file for all the fits files in a given data directory from its header, identifies correct frames (science, continuum and calibration lamps) based on the user input, and offers an option to the user for eyeballing and accepting/removing of the frames, does the cleaning of raw science frames and yields final wavelength calibrated spectra of all orders simultaneously.

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S. Ghosh, J. Ninan, D. Ojha, et. al.
Mon, 12 Dec 22
3/52

Comments: 10 pages, 6 figures, accepted for publication in the Special Issue of Journal of Astrophysics & Astronomy, 2022, Star formation studies in context of NIR instruments on 3.6m DOT, held at ARIES, Nainital during 4-7, May, 2022

Analytic approximations of scattering effects on beam chromaticity in 21-cm global experiments [IMA]

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http://arxiv.org/abs/2212.04526


Scattering from objects near an antenna produce correlated signals from strong compact radio sources in a manner similar to those used by the Sea Interferometer to measure the radio source positions using the fine frequency structure in the total power spectrum of a single antenna. These fringes or ripples due to correlated signal interference are present at a low level in the spectrum of any single antenna and are a major source of systematics in systems used to measure the global redshifted 21-cm signal from the early universe. In the Sea Interferometer a single antenna on a cliff above the sea is used to add the signal from the direct path to the signal from the path reflected from the sea thereby forming an interferometer. This was used for mapping radio sources with a single antenna by Bolton and Slee in the 1950s. In this paper we derive analytic expressions to determine the level of these ripples and compare these results in a few simple cases with electromagnetic modeling software to verify that the analytic calculations are sufficient to obtain the magnitude of the scattering effects on the measurements of the global 21-cm signal. These analytic calculations are needed to evaluate the magnitude of the effects in cases that are either too complex or take too much time to be modeled using software.

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A. Rogers, J. Barrett, J. Bowman, et. al.
Mon, 12 Dec 22
15/52

Comments: N/A

A Novel JupyterLab User Experience for Interactive Data Visualization [IMA]

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http://arxiv.org/abs/2212.03907


In the Jupyter ecosystem, data visualization is usually done with “widgets” created as notebook cell outputs. While this mechanism works well in some circumstances, it is not well-suited to presenting interfaces that are long-lived, interactive, and visually rich. Unlike the traditional Jupyter notebook system, the newer JupyterLab application provides a sophisticated extension infrastructure that raises new design possibilities. Here we present a novel user experience (UX) for interactive data visualization in JupyterLab that is based on an “app” that runs alongside the user’s notebooks, rather than widgets that are bound inside them. We have implemented this UX for the AAS WorldWide Telescope (WWT) visualization tool. JupyterLab’s messaging APIs allow the app to smoothly exchange data with multiple computational kernels, allowing users to accomplish tasks that are not possible using the widget framework. A new Jupyter server extension allows the frontend to request data from kernels asynchronously over HTTP, enabling interactive exploration of gigapixel-scale imagery in WWT. While we have developed this UX for WWT, the overall design and the server extension are portable to other applications and have the potential to unlock a variety of new user activities that aren’t currently possible in “science platform” interfaces.

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P. Williams, J. Carifio, H. Norman, et. al.
Fri, 9 Dec 22
7/75

Comments: Submitted to proceedings of ADASS32; 8 pages, 3 figures. Try the WWT app at this https URL

The design and performance of the XL-Calibur anticoincidence shield [IMA]

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http://arxiv.org/abs/2212.04139


The XL-Calibur balloon-borne hard X-ray polarimetry mission comprises a Compton-scattering polarimeter placed at the focal point of an X-ray mirror. The polarimeter is housed within a BGO anticoincidence shield, which is needed to mitigate the considerable background radiation present at the observation altitude of ~40 km. This paper details the design, construction and testing of the anticoincidence shield, as well as the performance measured during the week-long maiden flight from Esrange Space Centre to the Canadian Northwest Territories in July 2022. The in-flight performance of the shield followed design expectations, with a veto threshold <100 keV and a measured background rate of ~0.5 Hz (20-40 keV). This is compatible with the scientific goals of the mission, where %-level minimum detectable polarisation is sought for a Hz-level source rate.

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N. Iyer, M. Kiss, M. Pearce, et. al.
Fri, 9 Dec 22
19/75

Comments: Submitted to Nuclear Instruments and Methods A

GONG third generation camera: Detector selection and feasibility study [IMA]

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http://arxiv.org/abs/2212.03963


Aging GONG second generation cameras (Silicon Mountain Design(TM) cameras) were planned to be replaced after their long service of more than a decade. This prompted a market-wide search for a potential replacement detector to meet the GONG science requirements. This report provides some history of the search process, a comparison between CMOS and CCD type sensors and then a quantitative evaluation of potential candidates to arrive at final selection. Further, a feasibility study of the selected sensor for adaptation to GONG optical system was done and sensor characteristics were independently verified in the laboratory. This technical report gives description of these studies and tests.

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S. Gosain, J. Harvey, D. Branson, et. al.
Fri, 9 Dec 22
51/75

Comments: 13 pages, 12 figures

The wide-field, multiplexed, spectroscopic facility WEAVE: Survey design, overview, and simulated implementation [IMA]

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http://arxiv.org/abs/2212.03981


WEAVE, the new wide-field, massively multiplexed spectroscopic survey facility for the William Herschel Telescope, will see first light in late 2022. WEAVE comprises a new 2-degree field-of-view prime-focus corrector system, a nearly 1000-multiplex fibre positioner, 20 individually deployable ‘mini’ integral field units (IFUs), and a single large IFU. These fibre systems feed a dual-beam spectrograph covering the wavelength range 366$-$959\,nm at $R\sim5000$, or two shorter ranges at $R\sim20\,000$. After summarising the design and implementation of WEAVE and its data systems, we present the organisation, science drivers and design of a five- to seven-year programme of eight individual surveys to: (i) study our Galaxy’s origins by completing Gaia’s phase-space information, providing metallicities to its limiting magnitude for $\sim$3 million stars and detailed abundances for $\sim1.5$ million brighter field and open-cluster stars; (ii) survey $\sim0.4$ million Galactic-plane OBA stars, young stellar objects and nearby gas to understand the evolution of young stars and their environments; (iii) perform an extensive spectral survey of white dwarfs; (iv) survey $\sim400$ neutral-hydrogen-selected galaxies with the IFUs; (v) study properties and kinematics of stellar populations and ionised gas in $z<0.5$ cluster galaxies; (vi) survey stellar populations and kinematics in $\sim25\,000$ field galaxies at $0.3\lesssim z \lesssim 0.7$; (vii) study the cosmic evolution of accretion and star formation using $>1$ million spectra of LOFAR-selected radio sources; (viii) trace structures using intergalactic/circumgalactic gas at $z>2$. Finally, we describe the WEAVE Operational Rehearsals using the WEAVE Simulator.

Read this paper on arXiv…

S. Jin, S. Trager, G. Dalton, et. al.
Fri, 9 Dec 22
59/75

Comments: 41 pages, 27 figures, accepted for publication by MNRAS

Ground-based Synoptic Studies of the Sun [IMA]

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http://arxiv.org/abs/2212.03247


Ground-based synoptic solar observations provide critical contextual data used to model the large-scale state of the heliosphere. The next decade will see a combination of ground-based telescopes and space missions that will study our Sun’s atmosphere microscopic processes with unprecedented detail. This white paper describes contextual observations from a ground-based network needed to fully exploit this new knowledge of the underlying physics that leads to the magnetic linkages between the heliosphere and the Sun. This combination of a better understanding of small-scale processes and the appropriate global context will enable a physics-based approach to Space Weather comparable to Terrestrial Weather forecasting.

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S. Gosain, V. Pillet, A. Pevtsov, et. al.
Thu, 8 Dec 22
12/63

Comments: 10 pages, 5 figures, White paper submitted to Heliodecadal 2024, Category: Basic Research, Solar Physics. arXiv admin note: text overlap with arXiv:1903.06944

A novel energy reconstruction method for the MAGIC stereoscopic observation [IMA]

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http://arxiv.org/abs/2212.03592


We present a new gamma ray energy reconstruction method based on Random Forest to be commonly used for the data analysis of the MAGIC Telescopes, a system of two Imaging Atmospheric Cherenkov Telescopes.
The energy resolution with the new energy reconstruction improves compared to the one obtained with the LUTs method. For standard observations i.e. dark conditions with pointing zenith (Zd) less than 35 deg for a point-like source, the energy resolution goes from $\sim 20\%$ at 100 GeV to $\sim 10\%$ at a few TeV.
In addition, the new method suppresses the outlier population in the energy error distribution, which is thus better described by a Gaussian distribution. The new energy reconstruction method enhances the reliability especially for the sources with steep spectra, in higher energies and/or in observations at higher Zd pointings.
We validate the new method in different ways and demonstrate some cases of its remarkable benefit in spectral analysis with simulated observation data.

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K. Ishio and D. Paneque
Thu, 8 Dec 22
13/63

Comments: Submitted version

A Neural Network Approach for Selecting Track-like Events in Fluorescence Telescope Data [IMA]

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http://arxiv.org/abs/2212.03787


In 2016-2017, TUS, the world’s first experiment for testing the possibility of registering ultra-high energy cosmic rays (UHECRs) by their fluorescent radiation in the night atmosphere of Earth was carried out. Since 2019, the Russian-Italian fluorescence telescope (FT) Mini-EUSO (“UV Atmosphere”) has been operating on the ISS. The stratospheric experiment EUSO-SPB2, which will employ an FT for registering UHECRs, is planned for 2023. We show how a simple convolutional neural network can be effectively used to find track-like events in the variety of data obtained with such instruments.

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M. Zotov and D. Sokolinskii
Thu, 8 Dec 22
15/63

Comments: 5 pages, to be published in proceedings of the 37th Russian Cosmic Ray Conference (2022)

#Change: How Social Media is Accelerating STEM Inclusion [IMA]

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http://arxiv.org/abs/2212.03245


The vision of 2030STEM is to address systemic barriers in institutional structures and funding mechanisms required to achieve full inclusion in Science, Technology, Engineering, and Mathematics (STEM) and provide leadership opportunities for individuals from underrepresented populations across STEM sectors. 2030STEM takes a systems-level approach to create a community of practice that affirms diverse cultural identities in STEM. This is the first in a series of white papers based on 2030STEM Salons – discussions that bring together visionary stakeholders in STEM to think about innovative ways to infuse justice, equity, diversity, and inclusion into the STEM ecosystem. Our salons identify solutions that come from those who have been most affected by systemic barriers in STEM. Our first salon focused on the power of social media to accelerate inclusion and diversity efforts in STEM. Social media campaigns, such as the #XinSTEM initiatives, are powerful new strategies for accelerating change towards inclusion and leadership by underrepresented communities in STEM. This white paper highlights how #XinSTEM campaigns are redefining community, and provides recommendations for how scientific and funding institutions can improve the STEM ecosystem by supporting the #XinSTEM movement.

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J. Adams, C. Berry, R. Cohen, et. al.
Thu, 8 Dec 22
42/63

Comments: 13 pages, 2 Figures, Also uploaded to the Biorxiv

Photometry and astrometry with JWST — II. NIRCam geometric distortion correction [IMA]

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http://arxiv.org/abs/2212.03256


In preparation to make the most of our own planned James Webb Space Telescope investigations, we take advantage of publicly available calibration and early-science observations to independently derive and test a geometric-distortion solution for NIRCam detectors. Our solution is able to correct the distortion to better than ~0.2 mas. Current data indicate that the solution is stable and constant over the investigated filters, temporal coverage, and even over the available filter combinations. We successfully tested our geometric-distortion solution matching the JWST and archive HST catalogues. We considered three different applications: (i) cluster-field separation for the stars in the globular cluster M92; (ii) measuring the internal proper motions for M92’s stars; (iii) measuring the internal proper motions for the stars in the Large Magellanic Cloud system. While we were not able to detect significant variations of the geometric distortion solution over 22 days, it is clear that more data are still necessary to have a better understanding of the instrument and to characterise the solution to a higher level of accuracy. To our knowledge, the here-derived geometric-distortion solution for NIRCam is the best available and we publicly release it, as many other investigations could potentially benefit from it. Along with our geometric-distortion solution, we also release a Python tool to convert the raw-pixels coordinates of each detector into distortion-free positions, and also to put all the ten detectors of NIRCam into a common reference system.

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M. Griggio, D. Nardiello and L. Bedin
Thu, 8 Dec 22
43/63

Comments: 13 pages, 12 figures (4 in low resolution), 2 tables. Submitted. Associated files soon at this https URL

Optical and Opto-mechanical Analysis and Design of the Telescope for the Ariel Mission [IMA]

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http://arxiv.org/abs/2212.03686


The Atmospheric Remote-sensing Infrared Exoplanet Large-survey (Ariel) is the first space mission dedicated to measuring the chemical composition and thermal structures of thousands of transiting exoplanets. Ariel was adopted in 2020 as the M4 mission in ESA “Cosmic Vision” program, with launch expected in 2029. The mission will operate from the Sun-Earth Lagrange Point L2. The scientific payload consists of two instruments: a high resolution spectrometer in the waveband 1.95-7.8 microns, and a fine guidance system / visible photometer / low resolution near-infrared spectrometer. The instruments are fed a collimated beam from an unobscured, off-axis Cassegrain telescope. Instruments and telescope will operate at a temperature below 50 K. Telescope mirrors and supporting structures will be realized in aerospace-grade aluminum. Given the large aperture of the primary mirror (0.6 m$^2$), it is a choice of material that requires careful optical and opto-mechanical design, and technological advances in the three areas of mirror substrate thermal stabilization, optical surface polishing and optical coating. This thesis presents the work done by the author in these areas, as member of the team responsible for designing and manufacturing the telescope and mirrors, starting with a systematic review of the optical and opto-mechanical requirements and design choices of the Ariel telescope, in the context of previous development work and scientific goals and requirements of the mission. The review then progresses with opto-mechanical design, examining the most important choices in terms of structural and thermal design, and with a statistical analysis of the deformations of the optical surface of the telescope mirrors and of their alignment in terms of rigid body motions. The details of the qualification work on thermal stabilization, polishing and coating are then presented.

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P. Chioetto
Thu, 8 Dec 22
51/63

Comments: Pre-print of the final dissertation for the PhD Course in “Sciences, Technologies and Measurements for Space”, 35th Series, at the Center for Studies and Space Activities “G.Colombo” – CISAS, University of Padova, Italy. Course coordinator: Prof. Francesco Picano, Supervisor: Dr. Paola Zuppella, Co-supervisor: Dr. Vania Da Deppo

JWST MIRI/MRS in-flight absolute flux calibration and tailored fringe correction for unresolved sources [IMA]

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http://arxiv.org/abs/2212.03596


The MRS is one of the four observing modes of JWST/MIRI. Using JWST in-flight data of unresolved (point) sources, we can derive the MRS absolute spectral response function (ASRF) starting from raw data. Spectral fringing plays a critical role in the derivation and interpretation of the MRS ASRF. In this paper, we present an alternative way to calibrate the data. Firstly, we aim to derive a fringe correction that accounts for the dependence of the fringe properties on the MIRI pupil illumination and detector pixel sampling of the point spread function. Secondly, we aim to derive the MRS ASRF using an absolute flux calibrator observed across the full 5 to 28 $\mu$m wavelength range of the MRS. Thirdly, we aim to apply the new ASRF to the spectrum of a G dwarf and compare with the output of the JWST/MIRI default data reduction pipeline. Finally, we examine the impact of the different fringe corrections on the detectability of molecular features in the G dwarf and K giant. The absolute flux calibrator HD 163466 (A-star) is used to derive tailored point source fringe flats at each of the default dither locations of the MRS. The fringe-corrected point source integrated spectrum of HD 163466 is used to derive the MRS ASRF using a theoretical model for the stellar continuum. A cross-correlation is run to quantify the uncertainty on the detection of CO, SiO, and OH in the K giant and CO in the G dwarf for different fringe corrections. The point-source-tailored fringe correction and ASRF are found to perform at the same level as the current corrections, beating down the fringe contrast to the sub-percent level, whilst mitigating the alteration of real molecular features. The same tailored solutions can be applied to other MRS unresolved targets. A pointing repeatability issue in the MRS limits the effectiveness of the tailored fringe flats is at short wavelengths.

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D. Gasman, I. Argyriou, G. Sloan, et. al.
Thu, 8 Dec 22
58/63

Comments: N/A

The Importance of Co-located VLBI Intensive Stations and GNSS Receivers: A case study of the Maunakea VLBI and GNSS stations during the 2018 Hawai`i earthquake [IMA]

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http://arxiv.org/abs/2212.03453


Frequent, low-latency measurements of the Earth’s rotation phase, UT1$-$UTC, critically support the current estimate and short-term prediction of this highly variable Earth Orientation Parameter (EOP). Very Long Baseline Interferometry (VLBI) Intensive sessions provide the required data. However, the Intensive UT1$-$UTC measurement accuracy depends on the accuracy of numerous models, including the VLBI station position. Intensives observed with the Maunakea (Mk) and Pie Town (Pt) stations of the Very Long Baseline Array (VLBA) illustrate how a geologic event (i.e., the $M_w$ 6.9 Hawai`i Earthquake of May 4th, 2018) can cause a station displacement and an associated offset in the values of UT1$-$UTC measured by that baseline, rendering the data from the series useless until it is corrected. Using the non-parametric Nadaraya-Watson estimator to smooth the measured UT1$-$UTC values before and after the earthquake, we calculate the offset in the measurement to be 75.7 $\pm$ 4.6 $\mu$s. Analysis of the sensitivity of the Mk-Pt baseline’s UT1$-$UTC measurement to station position changes shows that the measured offset is consistent with the 67.2 $\pm$ 5.9 $\mu$s expected offset based on the 12.4 $\pm$ 0.6 mm total coseismic displacement of the Maunakea VLBA station determined from the displacement of the co-located global navigation satellite system (GNSS) station. GNSS station position information is known with a latency on the order of tens of hours, and thus can be used to correct the a priori position model of a co-located VLBI station such that it can continue to provide accurate measurements of the critical EOP UT1$-$UTC as part of Intensive sessions. The VLBI station position model would likely not be updated for several months. This contrast highlights the benefit of co-located GNSS and VLBI stations in support of the monitoring of UT1$-$UTC with single baseline Intensives. Abridged.

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C. Dieck, M. Johnson and D. MacMillan
Thu, 8 Dec 22
61/63

Comments: 18 pages, 4 figures, accepted for publication in Journal of Geodesy

Relative astrometry in an annular field [IMA]

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http://arxiv.org/abs/2212.03001


Background. Relative astrometry at or below the micro-arcsec level with a 1m class space telescope has been repeatedly proposed as a tool for exo-planet detection and characterization, as well as for several topics at the forefront of Astrophysics and Fundamental Physics. Aim. This paper investigates the potential benefits of an instrument concept based on an annular field of view, as compared to a traditional focal plane imaging a contiguous area close to the telescope optical axis. Method. Basic aspects of relative astrometry are reviewed as a function of the distribution on the sky of reference stars brighter than G = 12 mag (from Gaia EDR3). Statistics of field stars for targets down to G = 8 mag is evaluated by analysis and simulation. Results. Observation efficiency benefits from prior knowledge on individual targets, since source model is improved with few measurements. Dedicated observations (10-20 hours) can constrain the orbital inclination of exoplanets to a few degrees. Observing strategy can be tailored to include a sample of stars, materialising the reference frame, sufficiently large to average down the residual catalogue errors to the desired microarcsec level. For most targets, the annular field provides typically more reference stars, by a factor four to seven in our case, than the conventional field. The brightest reference stars for each target are up to 2 mag brighter. Conclusions. The proposed annular field telescope concept improves on observation flexibility and/or astrometric performance with respect to conventional designs. It appears therefore as an appealing contribution to optimization of future relative astrometry missions.

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M. Gai, A. Vecchiato, A. Riva, et. al.
Wed, 7 Dec 22
4/74

Comments: 20 pages, 16 figures

Real-time Data Ingestion at the Keck Observatory Archive (KOA) [IMA]

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http://arxiv.org/abs/2212.02576


Since February of this year, KOA began to prepare, transfer, and ingest data as they were acquired in near-real time; in most cases data are available to observers through KOA within one minute of acquisition. Real-time ingestion will be complete for all active instruments by the end of Summer 2022. The observatory is supporting the development of modern Python data reduction pipelines, which when delivered, will automatically create science-ready data sets at the end of each night for ingestion into the archive. This presentation will describe the infrastructure developed to support real-time data ingestion, itself part of a larger initiative at the Observatory to modernize end-to-end operations.
During telescope operations, the software at WMKO is executed automatically when a newly acquired file is recognized through monitoring a keyword-based observatory control system; this system is used at Keck to execute virtually all observatory functions. The monitor uses callbacks built into the control system to begin data preparation of files for transmission to the archive on an individual basis: scheduling scripts or file system related triggers are unnecessary. An HTTP-based system called from the Flask micro-framework enables file transfers between WMKO and NExScI and triggers data ingestion at NExScI. The ingestion system at NEXScI is a compact (4 KLOC), highly fault-tolerant, Python-based system. It uses a shared file system to transfer data from WMKO to NExScI. The ingestion code is instrument agnostic, with instrument parameters read from configuration files. It replaces an unwieldy (50 KLOC) C-based system that had been in use since 2004.

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G. Berriman, M. Brodheim, M. Brown, et. al.
Wed, 7 Dec 22
19/74

Comments: 4 pages, 3 figures

Topological Designs for Scalar Vortex Coronagraphs [IMA]

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http://arxiv.org/abs/2212.02633


The detection and characterization of Earth-like exoplanets around Sun-like stars for future flagship missions requires coronagraphs to achieve contrasts on the order of 1e-10 at close angular separations and over large spectral bandwidths (>=20%). We present our progress thus far on exploring the potential for scalar vortex coronagraphs (SVCs) in direct exoplanet imaging. SVCs are an attractive alternative to vector vortex coronagraphs (VVCs), which have recently demonstrated 6e-9 raw contrast in 20% broadband light but are polarization dependent. SVCs imprint the same phase ramp on the incoming light and do not require polarization splitting, but are inherently limited by their chromatic behavior. Several SVC designs have been proposed in recent years to solve this issue by modulating or wrapping the azimuthal phase function according to specific patterns. For one such design, the staircase SVC, we present our best experimental SVC results demonstrating raw contrast of 2e-7 in 10% broadband light. Since SVC broadband performance and aberration sensitivities are highly dependent on topology, we conducted a comparative study of several SVC designs to optimize for high contrast across a range of bandwidths. Furthermore, we present a new coronagraph optimization tool to predict performance in order to find an achromatic solution.

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N. Desai, J. Llop-Sayson, A. Bertrou-Cantou, et. al.
Wed, 7 Dec 22
21/74

Comments: N/A

Coma Off It: Removing Variable Point Spread Functions from Astronomical Images [IMA]

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http://arxiv.org/abs/2212.02594


We describe a method for regularizing, post-facto, the point-spread function of a telescope or other imaging instrument, across its entire field of view. Imaging instruments in general blur point sources of light by local convolution with a point-spread function that varies slowly across the field of view, due to coma, spherical aberration, and similar effects. It is possible to regularize the PSF in post-processing, producing data with a uniform and narrow “effective PSF” across the entire field of view. In turn, the method enables seamless wide-field astronomical mosaics at higher resolution than would otherwise be achievable, and potentially changes the design trade space for telescopes, lenses, and other optical systems where data uniformity is important. The method does not require access to the instrument that required the data, and can be bootstrapped from existing data sets that include starfield images.

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J. Hughes, C. DeForest and D. Seaton
Wed, 7 Dec 22
27/74

Comments: 11 pages; submitted to Astrophysical Journal

Astronomical source detection in radio continuum maps with deep neural networks [IMA]

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http://arxiv.org/abs/2212.02538


Source finding is one of the most challenging tasks in upcoming radio continuum surveys with SKA precursors, such as the Evolutionary Map of the Universe (EMU) survey of the Australian SKA Pathfinder (ASKAP) telescope. The resolution, sensitivity, and sky coverage of such surveys is unprecedented, requiring new features and improvements to be made in existing source finders. Among them, reducing the false detection rate, particularly in the Galactic plane, and the ability to associate multiple disjoint islands into physical objects. To bridge this gap, we developed a new source finder, based on the Mask R-CNN object detection framework, capable of both detecting and classifying compact, extended, spurious, and poorly imaged sources in radio continuum images. The model was trained using ASKAP EMU data, observed during the Early Science and pilot survey phase, and previous radio survey data, taken with the VLA and ATCA telescopes. On the test sample, the final model achieves an overall detection completeness above 85\%, a reliability of $\sim$65\%, and a classification precision/recall above 90\%. Results obtained for all source classes are reported and discussed.

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S. Riggi, D. Magro, R. Sortino, et. al.
Wed, 7 Dec 22
36/74

Comments: 18 pages, 11 figures

Probing Accretion Turbulence in the Galactic Center with EHT Polarimetry [IMA]

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http://arxiv.org/abs/2212.02544


Magnetic fields grown by instabilities driven by differential rotation are believed to be essential to accretion onto black holes. These instabilities saturate in a turbulent state; therefore, the spatial and temporal variability in the horizon-resolving images of Sagittarius A* (Sgr A) will be able to empirically assess this critical aspect of accretion theory. However, interstellar scattering blurs high-frequency radio images from the Galactic center and introduces spurious small-scale structures, complicating the interpretation of spatial fluctuations in the image. We explore the impact of interstellar scattering on the polarized images of Sgr A and demonstrate that for credible physical parameters, the intervening scattering is non-birefringent. Therefore, we construct a scattering mitigation scheme that exploits horizon-resolving polarized millimeter/submillimeter VLBI observations to generate statistical measures of the intrinsic spatial fluctuations and therefore the underlying accretion flow turbulence. An optimal polarization basis is identified, corresponding to measurements of the fluctuations in magnetic field orientation in three dimensions. We validate our mitigation scheme using simulated data sets and find that current and future ground-based experiments will readily be able to accurately measure the image-fluctuation power spectrum.

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C. Ni, A. Broderick and R. Gold
Wed, 7 Dec 22
62/74

Comments: N/A

A Standardized Framework for Collecting Graduate Student Input in Faculty Searches [IMA]

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http://arxiv.org/abs/2212.01456


We present a procedure designed to standardize input received during faculty searches with the goal of amplifying student voices. The framework was originally used to collect feedback from graduate students, but it can be adapted easily to collect feedback from undergraduate students, faculty, staff or other stakeholders. Implementing this framework requires agreement across participating parties and minimal organization prior to the start of faculty candidate visits.

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Y. Asali, K. Gerbig, A. Ghosh, et. al.
Tue, 6 Dec 22
3/87

Comments: 9 Pages, 6 Figures, Posted on Bulletin of the American Astronomical Society (BAAS)

panco2: a Python library to measure intracluster medium pressure profiles from Sunyaev-Zeldovich observations [IMA]

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http://arxiv.org/abs/2212.01439


We present panco2, an open-source Python library designed to extract galaxy cluster pressure profiles from maps of the thermal Sunyaev-Zeldovich effect. The extraction is based on forward modeling of the total observed signal, allowing to take into account usual features of millimeter observations, such as beam smearing, data processing filtering, and point source contamination. panco2 offers a large flexibility in the inputs that can be handled and in the analysis options, enabling refined analyses and studies of systematic effects. We detail the functionalities of the code, the algorithm used to infer pressure profile measurements, and the typical data products. We present examples of running sequences, and the validation on simulated inputs. The code is available on GitHub at https://github.com/fkeruzore/panco2, and comes with an extensive technical documentation to complement this paper at https://panco2.readthedocs.io.

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F. Kéruzoré, F. Mayet, E. Artis, et. al.
Tue, 6 Dec 22
7/87

Comments: 15 pages, 12 figures, for submission to the Open Journal of Astrophysics

Algorithms and radiation dynamics for the vicinity of black holes I. Methods and codes [IMA]

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http://arxiv.org/abs/2212.01532


We examine radiation and its effects on accretion disks orbiting astrophysical black holes. These disks are thermally radiating and can be geometrically and optically thin or thick. In this first paper of the series, we discuss the physics and the formulation required for this study. Subsequently, we construct and solve the relativistic radiative transfer equation, or find suitable solutions where that is not possible. We continue by presenting some of the accretion disks we considered for this work. We then describe the families of codes developed in order to study particle trajectories in strong gravity, calculate radiation forces exerted onto the disk material, and generate observation pictures of black hole systems at infinity. Furthermore, we also examine the veracity and accuracy of our work. Finally, we investigate how we can further use our results to estimate the black hole spin and the motion of disk material subjected to these radiation forces.

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L. Koutsantoniou
Tue, 6 Dec 22
11/87

Comments: 22 pages, 20 figures, 4 tables, accepted in Astronomy & Astrophysics

Polarized Maser Emission with In-Source Faraday Rotation [IMA]

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http://arxiv.org/abs/2212.01410


We discuss studies of polarization in astrophysical masers with particular emphasis on the case where the Zeeman splitting is small compared to the Doppler profile, resulting in a blend of the transitions between magnetic substates. A semi-classical theory of the molecular response is derived, and coupled to radiative transfer solutions for 1 and 2-beam linear masers, resulting in a set of non-linear, algebraic equations for elements of the molecular density matrix. The new code, PRISM, implements numerical methods to compute these solutions. Using PRISM, we demonstrate a smooth transfer between this case and that of wider splitting. For a J=1-0 system, with parameters based on the $v=1, J=1-0$ transition of SiO, we investigate the behaviour of linear and circular polarization as a function of the angle between the propagation axis and the magnetic field, and with the optical depth, or saturation state, of the model. We demonstrate how solutions are modified by the presence of Faraday rotation, generated by various abundances of free electrons, and that strong Faraday rotation leads to additional angles where Stokes-Q changes sign. We compare our results to a number of previous models, from the analytical limits derived by Goldreich, Keeley and Kwan in 1973, through computational results by W. Watson and co-authors, to the recent work by Lankhaar and Vlemmings in 2019. We find that our results are generally consistent with those of other authors given the differences of approach and the approximations made.

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T. Tobin, M. Gray and A. Kemball
Tue, 6 Dec 22
17/87

Comments: 36 pages, 15 figures. Accepted for publication in ApJ

Analytic auto-differentiable $Λ$CDM cosmography [IMA]

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http://arxiv.org/abs/2212.01937


I present general analytic expressions for distance calculations (comoving distance, time coordinate, and absorption distance) in the standard $\Lambda$CDM cosmology, allowing for the presence of radiation and for non-zero curvature. The solutions utilise the symmetric Carlson basis of elliptic integrals, which can be evaluated with fast numerical algorithms that allow trivial parallelisation on GPUs and automatic differentiation without the need for additional special functions. I introduce a PyTorch-based implementation in the phytorch.cosmology package and briefly examine its accuracy and speed in comparison with numerical integration and other known expressions (for special cases). Finally, I demonstrate an application to high-dimensional Bayesian analysis that utilises automatic differentiation through the distance calculations to efficiently derive posteriors for cosmological parameters from up to $10^6$ mock type Ia supernovae using variational inference.

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K. Karchev
Tue, 6 Dec 22
37/87

Comments: 13 pages, 5 figures + appendix; phytorch available at this https URL

Observation of night-time emissions of the Earth in the near UV range from the International Space Station with the Mini-EUSO detector [IMA]

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http://arxiv.org/abs/2212.02353


Mini-EUSO (Multiwavelength Imaging New Instrument for the Extreme Universe Space Observatory) is a telescope observing the Earth from the International Space Station since 2019. The instrument employs a Fresnel-lens optical system and a focal surface composed of 36 multi-anode photomultiplier tubes, 64 channels each, for a total of 2304 channels with single photon counting sensitivity. Mini-EUSO also contains two ancillary cameras to complement measurements in the near infrared and visible ranges. The scientific objectives of the mission range from the search for extensive air showers generated by Ultra-High Energy Cosmic Rays (UHECRs) with energies above 10$^{21}$ eV, the search for nuclearites and Strange Quark Matter (SQM), up to the study of atmospheric phenomena such as Transient Luminous Events (TLEs), meteors and meteoroids. Mini-EUSO can map the night-time Earth in the near UV range (between 290-430 nm) with a spatial resolution of about 6.3 km (full field of view of 44{\deg}) and a maximum temporal resolution of 2.5 $\mu$s, observing our planet through a nadir-facing UV-transparent window in the Russian Zvezda module. The detector saves triggered transient phenomena with a sampling rate of 2.5 $\mu$s and 320 $\mu$s, as well as continuous acquisition at 40.96 ms scale. In this paper we discuss the detector response and the flat-fielding and calibration procedures. Using the 40.96 ms data, we present $\simeq$6.3 km resolution night-time Earth maps in the UV band, and report on various emissions of anthropogenic and natural origin. We measure ionospheric airglow emissions of dark moonless nights over the sea and ground, studying the effect of clouds, moonlight, and artificial (towns, boats) lights. In addition to paving the way forward for the study of long-term variations of natural and artificial light, we also estimate the observation live-time of future UHECR detectors.

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M. Casolino, D. Barghini, M. Battisti, et. al.
Tue, 6 Dec 22
42/87

Comments: 49 pages, 27 figures, 1 table, published in Remote Sensing of Environment

Astrometric precision tests on TESS data [IMA]

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http://arxiv.org/abs/2212.02357


Background. Astrometry at or below the micro-arcsec level with an imaging telescope assumes that the uncertainty on the location of an unresolved source can be an arbitrarily small fraction of the detector pixel, given a sufficient photon budget. Aim. This paper investigates the geometric limiting precision, in terms of CCD pixel fraction, achieved by a large set of star field images, selected among the publicly available science data of the TESS mission. Method. The statistics of the distance between selected bright stars ($G \simeq 5\,mag$), in pixel units, is evaluated, using the position estimate provided in the TESS light curve files. Results. The dispersion of coordinate differences appears to be affected by long term variation and noisy periods, at the level of $0.01$ pixel. The residuals with respect to low-pass filtered data (tracing the secular evolution), which are interpreted as the experimental astrometric noise, reach the level of a few milli-pixel or below, down to $1/5,900$ pixel. Saturated images are present, evidencing that the astrometric precision is mostly preserved across the CCD columns, whereas it features a graceful degradation in the along column direction. The cumulative performance of the image set is a few micro-pixel across columns, or a few 10 micro-pixel along columns. Conclusions. The idea of astrometric precision down to a small fraction of a CCD pixel, given sufficient signal to noise ratio, is confirmed by real data from an in-flight science instrument to the $10^{-6}$ pixel level. Implications for future high precision astrometry missions are briefly discussed.

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M. Gai, A. Vecchiato, A. Riva, et. al.
Tue, 6 Dec 22
49/87

Comments: 13 pages, 8 figures

Using the SourceXtractor++ package for data reduction [IMA]

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http://arxiv.org/abs/2212.02428


The Euclid satellite is an ESA mission scheduled for launch in September 2023. To optimally perform critical stages of the data reduction, such as object detection and morphology determination, a new and modern software package was required. We have developed SourceXtractor++ as open source software for detecting and measuring sources in astronomical images. It is a complete redesign of the original SExtractor, written mainly in C++. The package follows a modular approach and facilitates the analysis of multiple overlapping sources over many images with different pixel grids. SourceXtractor++ is already operational in many areas of the Euclid processing, and we demonstrate here the capabilities of the current version v0.19 on the basis of a set of typical use cases, which are available for download

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M. Kümmel, A. Álvarez-Ayllón, E. Bertin, et. al.
Tue, 6 Dec 22
50/87

Comments: 4 pages, 2 figures

Searching for Intelligent Life in Gravitational Wave Signals Part I: Present Capabilities and Future Horizons [IMA]

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http://arxiv.org/abs/2212.02065


We show that the Laser Interferometer Gravitational Wave Observatory (LIGO) is a powerful instrument in the Search for Extra-Terrestrial Intelligence (SETI). LIGO’s ability to detect gravitational waves (GWs) from accelerating astrophysical sources, such as binary black holes, also provides the potential to detect extra-terrestrial mega-technology, such as Rapid And/or Massive Accelerating spacecraft (RAMAcraft). We show that LIGO is sensitive to RAMAcraft of $1$ Jupiter mass accelerating to a fraction of the speed of light (e.g. $10\%$) up to about $100\,{\rm kpc}$. Existing SETI searches probe on the order of thousands to tens of thousands of stars for human-scale technology (e.g. radiowaves), whereas LIGO can probe all $10^{11}$ stars in the Milky Way for RAMAcraft. Moreover, thanks to the $f^{-1}$ scaling of the GW signal produced by these sources, our sensitivity to these objects will increase as low-frequency, space-based detectors are developed and improved. In particular, we find that DECIGO and the Big Bang Observer (BBO) will be about 100 times more sensitive than LIGO, increasing the search volume by 10$^{6}$. In this paper, we calculate the waveforms for linearly accelerating RAMAcraft in a form suitable for LIGO, Virgo, or KAGRA searches and provide the range for a variety of possible masses and accelerations. We expect that the current and upcoming GW detectors will soon become an excellent complement to the existing SETI efforts.

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L. Sellers, A. Bobrick, G. Martire, et. al.
Tue, 6 Dec 22
63/87

Comments: 18 pages, 12 figures, to be submitted to MNRAS, comments welcome

An Unsupervised Machine Learning Method for Electron–Proton Discrimination of the DAMPE Experiment [IMA]

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http://arxiv.org/abs/2212.01843


Galactic cosmic rays are mostly made up of energetic nuclei, with less than $1\%$ of electrons (and positrons). Precise measurement of the electron and positron component requires a very efficient method to reject the nuclei background, mainly protons. In this work, we develop an unsupervised machine learning method to identify electrons and positrons from cosmic ray protons for the Dark Matter Particle Explorer (DAMPE) experiment. Compared with the supervised learning method used in the DAMPE experiment, this unsupervised method relies solely on real data except for the background estimation process. As a result, it could effectively reduce the uncertainties from simulations. For three energy ranges of electrons and positrons, 80–128 GeV, 350–700 GeV, and 2–5 TeV, the residual background fractions in the electron sample are found to be about (0.45 $\pm$ 0.02)$\%$, (0.52 $\pm$ 0.04)$\%$, and (10.55 $\pm$ 1.80)$\%$, and the background rejection power is about (6.21 $\pm$ 0.03) $\times$ $10^4$, (9.03 $\pm$ 0.05) $\times$ $10^4$, and (3.06 $\pm$ 0.32) $\times$ $10^4$, respectively. This method gives a higher background rejection power in all energy ranges than the traditional morphological parameterization method and reaches comparable background rejection performance compared with supervised machine learning~methods.

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Z. Xu, X. Li, M. Cui, et. al.
Tue, 6 Dec 22
66/87

Comments: 10 pages, 5 figures, 1 table

High Resolution VLBI Astrometry with the $θ-θ$ Transform [IMA]

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http://arxiv.org/abs/2212.01417


The recent development of $\theta-\theta$ techniques in pulsar scintillometry has opened the door for new high resolution imaging techniques of the scattering medium. By solving the phase retrieval problem and recovering the wavefield from a pulsar dynamic spectrum, the Doppler shift, time delay, and phase offset of individual images can be determined. However, the results of phase retrieval from a single dish are only know up to a constant phase rotation, which prevents their use for astrometry using Very Long Baseline Interferometry. We present an extension to previous $\theta-\theta$ methods using the interferometric visibilities between multiple stations to calibrate the wavefields. When applied to existing data for PSR B0834+06 we measure the effective screen distance and lens orientation with five times greater precision than previous works.

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D. Baker, W. Brisken, M. Kerkwijk, et. al.
Tue, 6 Dec 22
70/87

Comments: N/A

Correction factors of the measurement errors of the LAMOST-LRS stellar parameters [IMA]

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http://arxiv.org/abs/2212.02018


We aim to investigate the propriety of stellar parameter errors of the official data release of the LAMOST low-resolution spectroscopy (LRS) survey. We diagnose the errors of radial velocity (RV), atmospheric parameters ([Fe/H], T eff , log g) and {\alpha}-enhancement ([{\alpha}/M]) for the latest data release version of DR7, including 6,079,235 effective spectra of 4,546,803 stars. Based on the duplicate observational sample and comparing the deviation of multiple measurements to their given errors, we find that, in general, the error of [{\alpha}/M] is largely underestimated, and the error of radial velocity is slightly overestimated. We define a correction factor k to quantify these misestimations and correct the errors to be expressed as proper internal uncertainties. Using this self-calibration technique, we find that the k-factors significantly vary with the stellar spectral types and the spectral signal-to-noise ratio (SNR). Particularly, we reveal a strange but evident trend between k-factors and error themselves for all five stellar parameters. Larger errors tend to have smaller k-factor values, i.e., they were more overestimated. After the correction, we recreate and quantify the tight correlations between SNR and errors, for all five parameters, while these correlations have dependence on spectral types. It also suggests that the parameter errors from each spectrum should be corrected individually. Finally, we provide the error correction factors of each derived parameter of each spectrum for the entire LAMOST-LRS DR7.

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S. Zhang, G. Hu, R. Liu, et. al.
Tue, 6 Dec 22
78/87

Comments: 17 pages, 9 figures, 4 Tables, Accepted for publication in Research in Astronomy and Astrophysics (RAA)

Applications of AI in Astronomy [IMA]

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http://arxiv.org/abs/2212.01493


We provide a brief, and inevitably incomplete overview of the use of Machine Learning (ML) and other AI methods in astronomy, astrophysics, and cosmology. Astronomy entered the big data era with the first digital sky surveys in the early 1990s and the resulting Terascale data sets, which required automating of many data processing and analysis tasks, for example the star-galaxy separation, with billions of feature vectors in hundreds of dimensions. The exponential data growth continued, with the rise of synoptic sky surveys and the Time Domain Astronomy, with the resulting Petascale data streams and the need for a real-time processing, classification, and decision making. A broad variety of classification and clustering methods have been applied for these tasks, and this remains a very active area of research. Over the past decade we have seen an exponential growth of the astronomical literature involving a variety of ML/AI applications of an ever increasing complexity and sophistication. ML and AI are now a standard part of the astronomical toolkit. As the data complexity continues to increase, we anticipate further advances leading towards a collaborative human-AI discovery.

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S. Djorgovski, A. Mahabal, M. Graham, et. al.
Tue, 6 Dec 22
79/87

Comments: 12 pages, 1 figure, an invited review chapter, to appear in: Artificial Intelligence for Science, eds. A. Choudhary, G. Fox and T. Hey, Singapore: World Scientific, in press (2023)

The Tracking Tapered Gridded Estimator (TTGE) for the power spectrum from drift scan observations [IMA]

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http://arxiv.org/abs/2212.01251


Intensity mapping with the redshifted 21-cm line is an emerging tool in cosmology. Drift scan observations, where the antennas are fixed to the ground and the telescope’s pointing center (PC) changes continuously on the sky due to earth’s rotation, provide broad sky coverage and sustained instrumental stability needed for 21-cm intensity mapping. Here we present the Tracking Tapered Grided Estimator (TTGE) to quantify the power spectrum of the sky signal estimated directly from the visibilities measured in drift scan radio interferometric observations. The TTGE uses the data from the different PC to estimate the power spectrum of the signal from a small angular region located around a fixed tracking center (TC). The size of this angular region is decided by a suitably chosen tapering window function which serves to reduce the foreground contamination from bright sources located at large angles from the TC. It is possible to cover the angular footprint of the drift scan observations using multiple TC, and combine the estimated power spectra to increase the signal to noise ratio. Here we have validated the TTGE using simulations of $154 \, {\rm MHz}$ MWA drift scan observations. We show that the TTGE can recover the input model angular power spectrum $C_{\ell}$ within $20 \%$ accuracy over the $\ell$ range $40 < \ell < 700$.

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S. Chatterjee, S. Bharadwaj, S. Choudhuri, et. al.
Mon, 5 Dec 22
12/63

Comments: Accepted for publication in MNRAS

Characterization of Low-noise Backshort-Under-Grid Kilopixel Transition Edge Sensor Arrays for PIPER [IMA]

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http://arxiv.org/abs/2212.01370


We present laboratory characterization of kilo-pixel, filled backshort-under-grid (BUG) transition-edge sensor (TES) arrays developed for the Primordial Inflation Polarization ExploreR (PIPER) balloon-borne instrument. PIPER is designed to map the polarization of the CMB on the largest angular scales and characterize dust foregrounds by observing a large fraction of the sky in four frequency bands in the range 200 to 600 GHz. The BUG TES arrays are read out by planar SQUID-based time division multiplexer chips (2dMUX) of matching form factor and hybridized directly with the detector arrays through indium bump bonding. Here, we discuss the performance of the 2dMUX and present measurements of the TES transition temperature, thermal conductance, saturation power, and preliminary noise performance. The detectors achieve saturation power below 1 pW and phonon noise equivalent power (NEP) on the order of a few aW/rtHz. Detector performance is further verified through pre-flight tests in the integrated PIPER receiver, performed in an environment simulating balloon float conditions.

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R. Datta, S. Dahal, E. Switzer, et. al.
Mon, 5 Dec 22
28/63

Comments: 11 pages, 11 figures

Ice Giant Exploration Philosophy: Simple, Affordable [IMA]

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http://arxiv.org/abs/2212.00803


The key to the exploration of the Ice Giant planets is avoiding cutting edge technology. Complexity produces delay and financial roadblocks. Simple robot scouts can be launched in time to utilize gravity assists from Jupiter in the early 2030s. Demands on NASA’s budget from large missions, such as Mars sample return, will not allow Flagship missions to Uranus and Neptune in the near term. The science goals of Ice Giant exploration can be accomplished by a series of fast, simple, affordable (FSA) craft. Separate lines of cost-capped Orbiters and Probes would be launched at a cadence dictated by trajectories and funding. Contractors would be selected using competitive Announcements of Opportunity (AO). The march of progress in spacecraft technology offers hope and a path forward. The key is to start small and keep it affordable.

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P. Horzempa
Mon, 5 Dec 22
35/63

Comments: N/A

Astro-COLIBRI 2 — an advanced platform for real-time multi-messenger discoveries [IMA]

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http://arxiv.org/abs/2212.00805


The study of flaring astrophysical events in the multi-messenger approach requires instantaneous follow-up observations to better understand the nature of these events through complementary observational data. We present Astro-COLIBRI as a meta-platform for the patchwork of different specific tools in the real-time multi-messenger ecosystem. The Astro-COLIBRI platform bundles and evaluates alerts about transients from various channels. It further automates the coordination of follow-up observations by providing and linking detailed information through its comprehensible graphical user interface. We present the functionalities using documented examples of Astro-COLIBRI usage through the community since its public release in August 2021. We highlight the use cases of Astro-COLIBRI for planning follow-up observations by professional and amateur astronomers, as well as checking predictions from theoretical models.

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P. Reichherzer, F. Schüssler, V. Lefranc, et. al.
Mon, 5 Dec 22
46/63

Comments: Platform website: www.astro-colibri.com