Category Archives: Instrumentation and Methods for Astrophysics

Gender and Precarity in Astronomy [IMA]

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http://arxiv.org/abs/2303.10105


Following the survey Well-being in astrophysics that was sent out in March 2021, to establish how astrophysics researchers, primarily in France, experience their career, some of the results were published in Webb et al. (2021). Here we further analyse the data to determine if gender can cause different experiences in astrophysics. We also study the impact on the well-being of temporary staff (primarily PhD students and postdocs), compared to permanent staff. Whilst more temporary staff stated that they felt permanently overwhelmed than permanent staff, the experiences in astrophysics for the different genders were in general very similar, except in one area. More than three times more females than males experienced harassment or discrimination, rising sharply for gender discrimination and sexual harassment, where all of those having experienced sexual harassment and who had provided their gender in the survey, were female. Further, as previously reported (Webb et al. 2021), 20% of the respondents had suffered mental health issues before starting their career in astrophysics. We found that whilst this group was split approximately equally with regards to males and females, the number rose sharply to almost 45% of astronomers experiencing mental health issues since starting in astrophysics. Of this population, there were 50% more females than males. This excess of females was almost entirely made up of the population of women that had been harassed or discriminated against.

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N. Webb, C. Bot, S. Charpinet, et. al.
Mon, 20 Mar 23
48/51

Comments: 5 pages, 1 figure, published in the SF2A-2022: Proceedings of the Annual meeting of the French Society of Astronomy and Astrophysics. Eds.: J. Richard, A. Siebert, E. Lagadec, N. Lagarde, O. Venot, J. Malzac, J.-B. Marquette, M. N’Diaye, D. Briot, pp.171-175

Imaging effects due to pixel distortions in CdZnTe (CZT) detectors — results from the HREXI Calibration Facility (HCF) [IMA]

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http://arxiv.org/abs/2303.10075


ProtoEXIST2 (P2) was a prototype imaging X-ray detector plane developed for wide-field Time Domain Astrophysics (TDA) in the 5 – 200 keV energy band. It was composed of an 8 $\times$ 8 array of 5 mm thick, 2cm $\times$ 2cm pixelated (32 $\times$ 32) CdZnTe (CZT) detectors with a 0.6 mm pitch that utilize the NuSTAR ASIC(NuASIC) for readout. During the initial detector development process leading up to post-flight examination of the entire detector plane, distortions in expected pixel positions and shapes were observed in a significant fraction of the detectors. The HREXI (High Resolution Energetic X-ray Imager) Calibration Facility (HCF) was designed and commissioned to improve upon these early experiments and to rapidly map out and characterize pixel non-uniformities and defects within CZT detector planes at resolutions down to 50 $\rm \mu$m. Using this facility, the sub-pixel level detector response of P2 was measured at 100 $\rm \mu$m resolution and analyzed to extract and evaluate the area and profile of individual pixels, their morphology across the entire P2 detector plane for comparison with previous measurements and to provide additional characterization. In this article, we evaluate the imaging performance of a coded-aperture telescope using the observed pixel morphology for P2 detectors. This investigation will serve as an initial guide for detector selection in the development of HREXI detector planes, for the future implementation of the 4pi X-Ray Imaging Observatory (4piXIO) mission which aims to provide simultaneous and continuous imaging of the full sky ($\rm 4\pi$ sr) in the 3-200 keV energy band with $\rm \simeq$ 2 arcmin angular resolution and $\simeq$ 10 arcsec source localization, as well as other, future coded-aperture instruments.

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A. Basak, B. Allen, J. Hong, et. al.
Mon, 20 Mar 23
49/51

Comments: N/A

VISIONS: The VISTA Star Formation Atlas — II. The data processing pipeline [IMA]

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http://arxiv.org/abs/2303.08840


The VISIONS public survey provides large-scale, multiepoch imaging of five nearby star-forming regions at subarcsecond resolution in the near-infrared. All data collected within the program and provided by the European Southern Observatory (ESO) science archive are processed with a custom end-to-end pipeline infrastructure to provide science-ready images and source catalogs. The data reduction environment has been specifically developed for the purpose of mitigating several shortcomings of the bona fide data products processed with software provided by the Cambridge Astronomical Survey Unit (CASU), such as spatially variable astrometric and photometric biases of up to 100 mas and 0.1 mag, respectively. At the same time, the resolution of coadded images is up to 20% higher compared to the same products from the CASU processing environment. Most pipeline modules are written in Python and make extensive use of C extension libraries for numeric computations, thereby simultaneously providing accessibility, robustness, and high performance. The astrometric calibration is performed relative to the Gaia reference frame, and fluxes are calibrated with respect to the source magnitudes provided in the Two Micron All Sky Survey (2MASS). For bright sources, absolute astrometric errors are typically on the order of 10 to 15 mas and fluxes are determined with subpercent precision. Moreover, the calibration with respect to 2MASS photometry is largely free of color terms. The pipeline produces data that are compliant with the ESO Phase 3 regulations and furthermore provides curated source catalogs that are structured similarly to those provided by the 2MASS survey.

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S. Meingast, H. Bouy, V. Fürnkranz, et. al.
Fri, 17 Mar 23
16/67

Comments: Accepted for publication in Astronomy & Astrophysics on 28 February 2023

The Tiny Time-series Transformer: Low-latency High-throughput Classification of Astronomical Transients using Deep Model Compression [IMA]

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http://arxiv.org/abs/2303.08951


A new golden age in astronomy is upon us, dominated by data. Large astronomical surveys are broadcasting unprecedented rates of information, demanding machine learning as a critical component in modern scientific pipelines to handle the deluge of data. The upcoming Legacy Survey of Space and Time (LSST) of the Vera C. Rubin Observatory will raise the big-data bar for time-domain astronomy, with an expected 10 million alerts per-night, and generating many petabytes of data over the lifetime of the survey. Fast and efficient classification algorithms that can operate in real-time, yet robustly and accurately, are needed for time-critical events where additional resources can be sought for follow-up analyses. In order to handle such data, state-of-the-art deep learning architectures coupled with tools that leverage modern hardware accelerators are essential. We showcase how the use of modern deep compression methods can achieve a $18\times$ reduction in model size, whilst preserving classification performance. We also show that in addition to the deep compression techniques, careful choice of file formats can improve inference latency, and thereby throughput of alerts, on the order of $8\times$ for local processing, and $5\times$ in a live production setting. To test this in a live setting, we deploy this optimised version of the original time-series transformer, t2, into the community alert broking system of FINK on real Zwicky Transient Facility (ZTF) alert data, and compare throughput performance with other science modules that exist in FINK. The results shown herein emphasise the time-series transformer’s suitability for real-time classification at LSST scale, and beyond, and introduce deep model compression as a fundamental tool for improving deploy-ability and scalable inference of deep learning models for transient classification.

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T. Jr., J. Peloton and J. McEwen
Fri, 17 Mar 23
51/67

Comments: 16 pages, 11 figures

Improved prior for adaptive optics point spread function estimation from science images: Application for deconvolution [IMA]

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http://arxiv.org/abs/2303.09422


Access to knowledge of the point spread function (PSF) of adaptive optics(AO)-assisted observations is still a major limitation when processing AO data. This limitation is particularly important when image analysis requires the use of deconvolution methods. As the PSF is a complex and time-varying function, reference PSFs acquired on calibration stars before or after the scientific observation can be too different from the actual PSF of the observation to be used for deconvolution, and lead to artefacts in the final image. We improved the existing PSF-estimation method based on the so-called marginal approach by enhancing the object prior in order to make it more robust and suitable for observations of resolved extended objects. Our process is based on a two-step blind deconvolution approach from the literature. The first step consists of PSF estimation from the science image. For this, we made use of an analytical PSF model, whose parameters are estimated based on a marginal algorithm. This PSF was then used for deconvolution. In this study, we first investigated the requirements in terms of PSF parameter knowledge to obtain an accurate and yet resilient deconvolution process using simulations. We show that current marginal algorithms do not provide the required level of accuracy, especially in the presence of small objects. Therefore, we modified the marginal algorithm by providing a new model for object description, leading to an improved estimation of the required PSF parameters. Our method fulfills the deconvolution requirement with realistic system configurations and different classes of Solar System objects in simulations. Finally, we validate our method by performing blind deconvolution with SPHERE/ZIMPOL observations of the Kleopatra asteroid.

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A. Lau, R. Fétick, B. Neichel, et. al.
Fri, 17 Mar 23
55/67

Comments: accepted for publication in Astronomy & Astrophysics (A&A)

The GRAVITY+ Project: Towards All-sky, Faint-Science, High-Contrast Near-Infrared Interferometry at the VLTI [IMA]

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http://arxiv.org/abs/2301.08071


The GRAVITY instrument has been revolutionary for near-infrared interferometry by pushing sensitivity and precision to previously unknown limits. With the upgrade of GRAVITY and the Very Large Telescope Interferometer (VLTI) in GRAVITY+, these limits will be pushed even further, with vastly improved sky coverage, as well as faint-science and high-contrast capabilities. This upgrade includes the implementation of wide-field off-axis fringe-tracking, new adaptive optics systems on all Unit Telescopes, and laser guide stars in an upgraded facility. GRAVITY+ will open up the sky to the measurement of black hole masses across cosmic time in hundreds of active galactic nuclei, use the faint stars in the Galactic centre to probe General Relativity, and enable the characterisation of dozens of young exoplanets to study their formation, bearing the promise of another scientific revolution to come at the VLTI.

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G. Collaboration, R. Abuter, P. Alarcon, et. al.
Fri, 20 Jan 23
16/72

Comments: Published in the ESO Messenger

A Multilevel Scheduling Framework for Distributed Time-domain Large-area Sky Survey Telescope Array [IMA]

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http://arxiv.org/abs/2301.07860


Telescope arrays are receiving increasing attention due to their promise of higher resource utilization, greater sky survey area, and higher frequency of full space-time monitoring than single telescopes. Compared with the ordinary coordinated operation of several telescopes, the new astronomical observation mode has an order of magnitude difference in the number of telescopes. It requires efficient coordinated observation by large-domain telescopes distributed at different sites. Coherent modeling of various abstract environmental constraints is essential for responding to multiple complex science goals. Also, due to competing science priorities and field visibility, how the telescope arrays are scheduled for observations can significantly affect observation efficiency. This paper proposes a multilevel scheduling model oriented toward the problem of telescope-array scheduling for time-domain surveys. A flexible framework is developed with basic functionality encapsulated in software components implemented on hierarchical architectures. An optimization metric is proposed to self-consistently weight contributions from time-varying observation conditions to maintain uniform coverage and efficient time utilization from a global perspective. The performance of the scheduler is evaluated through simulated instances. The experimental results show that our scheduling framework performs correctly and provides acceptable solutions considering the percentage of time allocation efficiency and sky coverage uniformity in a feasible amount of time. Using a generic version of the telescope-array scheduling framework, we also demonstrate its scalability and its potential to be applied to other astronomical applications.

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Y. Zhang, C. Yu, C. Sun, et. al.
Fri, 20 Jan 23
33/72

Comments: Accepted for publication in the Astronomical Journal

Supernova model discrimination with a kilotonne-scale Gd-H$_{2}$O Cherenkov detector [IMA]

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http://arxiv.org/abs/2301.08079


The supernova model discrimination capabilities of the WATCHMAN detector concept are explored. This cylindrical kilotonne-scale water Cherenkov detector design has been developed to detect reactor antineutrinos through inverse $\beta$-decay for non-proliferation applications but also has the ability to observe antineutrino bursts of core-collapse supernovae within our galaxy. Detector configurations with sizes ranging from 16 m to 22 m tank diameter and 10% to 20% PMT coverage are used to compare the expected observable antineutrino spectra based on the Nakazato, Vartanyan and Warren supernova models. These spectra are then compared to each other with a fixed event count of 100 observed inverse $\beta$-decay events and a benchmark supernova at 10 kpc distance from Earth. By comparing the expected spectra, each detector configuration’s ability to distinguish is evaluated. This analysis then demonstrates that the detector design is capable of meaningful event discrimination (95+% accuracy) with 100 observed supernova antineutrino events in any configuration. Furthermore, a larger tank configuration can maintain this performance at 10 kpc distance and above, indicating that overall target mass is the main factor for such a detector’s discrimination capabilities.

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Y. Schnellbach, J. Migenda, A. Carroll, et. al.
Fri, 20 Jan 23
42/72

Comments: 12 pages, 7 figures, 6 tables. For submission to JCAP

CRIRES$^{+}$ on sky at the ESO Very Large Telescope [IMA]

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http://arxiv.org/abs/2301.08048


The CRyogenic InfraRed Echelle Spectrograph (CRIRES) Upgrade project CRIRES$^{+}$ extended the capabilities of CRIRES. It transformed this VLT instrument into a cross-dispersed spectrograph to increase the wavelength range that is covered simultaneously by up to a factor of ten. In addition, a new detector focal plane array of three Hawaii 2RG detectors with a 5.3 $\mu$m cutoff wavelength replaced the existing detectors. Amongst many other improvements, a new spectropolarimetric unit was added and the calibration system has been enhanced. The instrument was installed at the VLT on Unit Telescope 3 at the beginning of 2020 and successfully commissioned and verified for science operations during 2021, partly remotely from Europe due to the COVID-19 pandemic. The instrument was subsequently offered to the community from October 2021 onwards. This article describes the performance and capabilities of the upgraded instrument and presents on sky results.

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R. Dorn, P. Bristow, J. Smoker, et. al.
Fri, 20 Jan 23
43/72

Comments: Accepted for publication in Astronomy and Astrophysics

Demonstrating the first 24-hour continuous vertical monitoring of the atmospheric optical turbulence [IMA]

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http://arxiv.org/abs/2301.07612


We report what is believed to be the first example of fully continuous, 24-hour vertical monitoring of atmospheric optical turbulence. This is achieved using a novel instrument, the 24-hour Shack-Hartmann Image Motion Monitor (24hSHIMM). Optical turbulence is a fundamental limitation for applications such as free-space optical communications, where it limits the achievable bandwidth, and ground-based optical astronomy, restricting the observational precision. Knowledge of the turbulence enables us to select the best sites, design optical instrumentation and optimise the operation of ground-based optical systems. The 24hSHIMM estimates the vertical optical turbulence coherence length, time, angle and Rytov variance from the measurement of a four-layer vertical turbulence profile and a wind speed profile retrieved from meteorological forecasts. To illustrate our advance we show the values of these parameters recorded during a 35-hour, continuous demonstration of the instrument. Due to its portability and ability to work in stronger turbulence, the 24hSHIMM can also operate in urban locations, providing the field with a truly continuous, versatile turbulence monitor for all but the most demanding of applications.

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R. Griffiths, J. Osborn, O. Farley, et. al.
Thu, 19 Jan 23
9/100

Comments: Accepted in Optics Express

Mineral Detection of Neutrinos and Dark Matter. A Whitepaper [IMA]

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http://arxiv.org/abs/2301.07118


Minerals are solid state nuclear track detectors – nuclear recoils in a mineral leave latent damage to the crystal structure. Depending on the mineral and its temperature, the damage features are retained in the material from minutes (in low-melting point materials such as salts at a few hundred degrees C) to timescales much larger than the 4.5 Gyr-age of the Solar System (in refractory materials at room temperature). The damage features from the $O(50)$ MeV fission fragments left by spontaneous fission of $^{238}$U and other heavy unstable isotopes have long been used for fission track dating of geological samples. Laboratory studies have demonstrated the readout of defects caused by nuclear recoils with energies as small as $O(1)$ keV. This whitepaper discusses a wide range of possible applications of minerals as detectors for $E_R \gtrsim O(1)$ keV nuclear recoils: Using natural minerals, one could use the damage features accumulated over $O(10)$ Myr$-O(1)$ Gyr to measure astrophysical neutrino fluxes (from the Sun, supernovae, or cosmic rays interacting with the atmosphere) as well as search for Dark Matter. Using signals accumulated over months to few-years timescales in laboratory-manufactured minerals, one could measure reactor neutrinos or use them as Dark Matter detectors, potentially with directional sensitivity. Research groups in Europe, Asia, and America have started developing microscopy techniques to read out the $O(1) – O(100)$ nm damage features in crystals left by $O(0.1) – O(100)$ keV nuclear recoils. We report on the status and plans of these programs. The research program towards the realization of such detectors is highly interdisciplinary, combining geoscience, material science, applied and fundamental physics with techniques from quantum information and Artificial Intelligence.

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S. Baum, P. Stengel, N. Abe, et. al.
Thu, 19 Jan 23
21/100

Comments: 113 pages, many pictures of tracks

The JWST Resolved Stellar Populations Early Release Science Program III: Photometric Star-Galaxy Separations for NIRCam [IMA]

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http://arxiv.org/abs/2301.07218


We present criteria for separately classifying stars and unresolved background galaxies in photometric catalogs generated with the point spread function (PSF) fitting photometry software DOLPHOT from images taken of Draco II, WLM, and M92 with the Near Infrared Camera (NIRCam) on JWST. Photometric quality metrics from DOLPHOT in one or two filters can recover a pure sample of stars. Conversely, colors formed between short-wavelength (SW) and long-wavelength (LW) filters can be used to effectively identify pure samples of galaxies. Our results highlight that the existing DOLPHOT output parameters can be used to reliably classify stars in our NIRCam data without the need to resort to external tools or more complex heuristics.

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J. Warfield, H. Richstein, N. Kallivayalil, et. al.
Thu, 19 Jan 23
39/100

Comments: 5 pages, 1 figure

Imaging faint sources with the extended solar gravitational lens [IMA]

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http://arxiv.org/abs/2301.07495


We consider resolved imaging of faint sources with the solar gravitational lens (SGL) while treating the Sun as an extended gravitating body. We use our new diffraction integral that describes how a spherical electromagnetic wave is modified by the static gravitational field of an extended body, represented by series of multipole moments characterizing its interior mass distribution. Dominated by the solar quadrupole moment, these deviations from spherical symmetry significantly perturb the image that is projected by the Sun into its focal region, especially at solar equatorial latitudes. To study the optical properties of the quadrupole SGL, we develop an approximate solution for the point spread function of such an extended lens. We also derive semi-analytical expressions to estimate signal levels from extended targets. With these tools, we study the impact of solar oblateness on imaging with the SGL. Given the small value of the solar quadrupole moment, the majority of the signal photons arriving from an extended target still appear within the image area projected by the monopole lens. However, these photons are scrambled, thus reducing the achievable signal-to-noise ratio during image recovery process (i.e., deconvolution). We also evaluate the spectral sensitivity for high-resolution remote sensing of exoplanets with the extended SGL. We assess the impact on image quality and demonstrate that despite the adverse effects of the quadrupole moment, the SGL remains uniquely capable of delivering high-resolution imaging and spectroscopy of faint, small and distant targets, notably terrestrial exoplanets within ~30–100 parsec from us.

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S. Turyshev and V. Toth
Thu, 19 Jan 23
47/100

Comments: 23 pages, 2 figures

Solaris: A Focused Solar Polar Discovery-class Mission to achieve the Highest Priority Heliophysics Science Now [IMA]

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http://arxiv.org/abs/2301.07647


Solaris is a transformative Solar Polar Discovery-class mission concept to address crucial outstanding questions that can only be answered from a polar vantage. Solaris will image the Sun’s poles from ~75 degree latitude, providing new insight into the workings of the solar dynamo and the solar cycle, which are at the foundation of our understanding of space weather and space climate. Solaris will also provide enabling observations for improved space weather research, modeling and prediction, revealing a unique, new view of the corona, coronal dynamics and CME eruptions from above.

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D. Hassler, S. Gibson, J. Newmark, et. al.
Thu, 19 Jan 23
55/100

Comments: This White Paper was submitted in 2022 to the United States National Academies Solar and Space Physics (Heliophysics) Decadal Survey

The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems: Best Practices for Data Collection in Cycle 2 and Beyond [IMA]

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http://arxiv.org/abs/2301.07199


We present a set of recommended best practices for JWST data collection for members of the community focussed on the direct imaging and spectroscopy of exoplanetary systems. These findings and recommendations are based on the early analysis of the JWST Early Release Science Program 1386, “High-Contrast Imaging of Exoplanets and Exoplanetary Systems with JWST.” Our goal is for this information to be useful for observers in preparation of JWST proposals for Cycle 2 and beyond. In addition to compiling a set of best practices from our ERS program, in a few cases we also draw on the expertise gained within the instrument commissioning programs, as well as include a handful of data processing best practices. We anticipate that this document will be regularly updated and resubmitted to arXiv.org to ensure that we have distributed our knowledge of best-practices for data collection as widely and efficiently as possible.

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S. Hinkley, B. Biller, A. Skemer, et. al.
Thu, 19 Jan 23
60/100

Comments: Not yet submitted for publication. Intended only to be a community resource for JWST Cycle 2 proposals

The Use of the Signal at an Optimal Distance from the Shower Core as a Surrogate for Shower Size [IMA]

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http://arxiv.org/abs/2301.07410


When analysing data from air-shower arrays, it has become common practice to use the signal at a considerable distance from the shower axis ($r_\text{opt}$) as a surrogate for the size of the shower. This signal, $S(r_\text{opt}$), can then be related to the primary energy in a variety of ways. After a brief review of the reasons behind the introduction of $r_\text{opt}$ laid out in a seminal paper by Hillas in 1969, it will be shown that $r_\text{opt}$, is a more effective tool when detectors are laid out on a triangular grid than when detectors are deployed on a square grid. This result may have implications for explaining the differences between the flux observed by the Auger and Telescope collaborations above 10\,EeV and should be kept in mind when designing new shower arrays.

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Q. Luce, D. Schmidt, O. Deligny, et. al.
Thu, 19 Jan 23
61/100

Comments: 8 pages, 4 figures

LIGO-India: A Decadal Assessment on Its Scope, Relevance, Progress, and Future [IMA]

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http://arxiv.org/abs/2301.07522


The LIGO-India project to build and operate an advanced LIGO (aLIGO) gravitational wave (GW) detector in India in collaboration with LIGO-USA was considered and initiated as an Indian national megascience project in 2011. Procedural formalities and site selection efforts progressed since then and the provisional approval for the Indian national project was obtained in 2016, immediately following the first direct detection of gravitational waves with the aLIGO detectors. With KAGRA GW detector in Japan being tuned to be part of the GW detector network, it is now the occasion to assess the progress of LIGO-India project, and evaluate its relevance and scope for gravitational wave science and astronomy. Various key factors like human-power, management, funding, schedule etc., in the implementation of the project are reassessed in the backdrop of the evolution of the global GW detector sensitivity. In what I consider as a realistic estimate, it will take more than a decade, beyond 2032, to commission the detector even with a fraction of the projected design sensitivity. I estimate that the budget for implementation will be more than doubled, to about Rs. 35 billion (> $430 million). The detrimental consequences for the project are discussed, from my personal point of view. However, a revamped action plan with urgency and the right leadership can make LIGO-India a late but significant success for multi-messenger astronomy for several years after 2032, because of its design similitude to the operational aLIGO detectors. For achieving this, it is imperative that the LIGO-India detector is replanned and launched in the post-O5 upgraded A# version, similar to the projected LIGO-USA detectors.

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C. Unnikrishnan
Thu, 19 Jan 23
74/100

Comments: 22 pages, 5 figures

High-uniformity TiN/Ti/TiN multilayers for the development of Microwave Kinetic Inductance Detector [IMA]

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http://arxiv.org/abs/2301.07579


Microwave Kinetic Inductance Detectors (MKIDs) are a class of superconducting cryogenic detectors that simultaneously exhibit energy resolution, time resolution and spatial resolution. The pixel yield of MKID arrays is usually a critical figure of merit in the characterisation of an MKIDs array. Currently, for MKIDs intended for the detection of optical and near-infrared photons, only the best arrays exhibit a pixel yield as high as 75-80%. The uniformity of the superconducting film used for the fabrication of MKIDs arrays is often regarded as the main limiting factor to the pixel yield of an array. In this paper we will present data on the uniformity of the TiN/Ti/TiN multilayers deposited at the Tyndall National Institute and compare these results with a statistical model that evaluates how inhomogeneities affect the pixel yield of an array.

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M. Luciab, E. Baldwin, G. Ulbricht, et. al.
Thu, 19 Jan 23
75/100

Comments: 11 pages, 7 figures. Proceedings Volume 12191, X-Ray, Optical, and Infrared Detectors for Astronomy X; 1219105 (2022)

Real-time RFI Filtering for uGMRT: Overview of the Released System and Relevance to the SKA [IMA]

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http://arxiv.org/abs/2301.07402


Radio Frequency Interference (RFI) of impulsive nature is created by sources like sparking on high-power transmission lines due to gap or corona discharge and automobile sparking, and it affects the entire observing frequency bands of low-frequency radio telescopes. Such RFI is a significant problem at the Upgraded Giant Metrewave Radio Telescope (uGMRT). A real-time RFI filtering scheme has been developed and implemented to mitigate the effect on astronomical observations. The scheme works in real-time on pre-correlation data from each antenna and allows the detection of RFI based on median absolute deviation statistics. The samples are identified as RFI based on user-defined thresholds and are replaced by digital noise, a constant or zeros. We review the testing and implementation of this system at the uGMRT. We illustrate the effectiveness of the filtering for continuum, spectral line and time-domain data. The real-time filter is released for regular observations in the bands falling in 250 – 1450 MHz, and recent observing cycles show growing usage. Further, we explain the relevance of the released system to the Square Kilometer Array (SKA) receiver chain and possible ways of implementation to meet the computational requirements.

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K. Buch, R. Kale, M. Muley, et. al.
Thu, 19 Jan 23
85/100

Comments: 15 pages, 11 figures, 4 tables; Accepted for publication in the JoAA special issue on the Indian participation in the SKA (2023)

HLC2: a highly efficient cross-matching framework for large astronomical catalogues on heterogeneous computing environments [IMA]

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http://arxiv.org/abs/2301.07331


Cross-matching operation, which is to find corresponding data for the same celestial object or region from multiple catalogues,is indispensable to astronomical data analysis and research. Due to the large amount of astronomical catalogues generated by the ongoing and next-generation large-scale sky surveys, the time complexity of the cross-matching is increasing dramatically. Heterogeneous computing environments provide a theoretical possibility to accelerate the cross-matching, but the performance advantages of heterogeneous computing resources have not been fully utilized. To meet the challenge of cross-matching for substantial increasing amount of astronomical observation data, this paper proposes Heterogeneous-computing-enabled Large Catalogue Cross-matcher (HLC2), a high-performance cross-matching framework based on spherical position deviation on CPU-GPU heterogeneous computing platforms. It supports scalable and flexible cross-matching and can be directly applied to the fusion of large astronomical cataloguesfrom survey missions and astronomical data centres. A performance estimation model is proposed to locate the performance bottlenecks and guide the optimizations. A two-level partitioning strategy is designed to generate an optimized data placement according to the positions of celestial objects to increase throughput. To make HLC2 a more adaptive solution, the architecture-aware task splitting, thread parallelization, and concurrent scheduling strategies are designed and integrated. Moreover, a novel quad-direction strategy is proposed for the boundary problem to effectively balance performance and completeness. We have experimentally evaluated HLC2 using public released catalogue data. Experiments demonstrate that HLC2 scales well on different sizes of catalogues and the cross-matching speed is significantly improved compared to the state-of-the-art cross-matchers.

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Y. Zhang, C. Yu, C. Sun, et. al.
Thu, 19 Jan 23
100/100

Comments: Accepted for publication in Monthly Notices of the Royal Astronomical Society

High Performance W-stacking for Imaging Radio Astronomy Data: a Parallel and Accelerated Solution [IMA]

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http://arxiv.org/abs/2301.06061


Current and upcoming radio-interferometers are expected to produce volumes of data of increasing size that need to be processed in order to generate the corresponding sky brightness distributions through imaging. This represents an outstanding computational challenge, especially when large fields of view and/or high resolution observations are processed. We have investigated the adoption of modern High Performance Computing systems specifically addressing the gridding, FFT-transform and w-correction of imaging, combining parallel and accelerated solutions. We have demonstrated that the code we have developed can support dataset and images of any size compatible with the available hardware, efficiently scaling up to thousands of cores or hundreds of GPUs, keeping the time to solution below one hour even when images of the size of the order of billion or tens of billion of pixels are generated. In addition, portability has been targeted as a primary objective, both in terms of usability on different computing platforms and in terms of performance. The presented results have been obtained on two different state-of-the-art High Performance Computing architectures.

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C. Gheller, G. Taffoni and D. Goz
Wed, 18 Jan 23
10/133

Comments: 16 pages, 12 figures, accepted for publication on RAS Techniques and Instruments

A First Look at the JWST MIRI/LRS Phase Curve of WASP-43b [IMA]

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http://arxiv.org/abs/2301.06350


We observed a full-orbit phase curve of the hot Jupiter WASP-43b with MIRI/LRS as part of the Transiting Exoplanet Community Early Release Science Program. Here we report preliminary findings for the instrument performance from the team’s MIRI Working Group. Overall we find that MIRI’s performance for phase curve observations is excellent, with a few minor caveats. The key takeaways for Cycle 2 planning with MIRI/LRS are: (1) long-duration observations (> 24 hours) have now been successfully executed; (2) for phase curves, we recommend including a one-hour burn-in period prior to taking science data to mitigate the effects of the ramp systematic; and (3) we do not yet recommend partial phase curve observations. In addition, we also find that: the position of the spectrum on the detector is stable to within 0.03 pixels over the full 26.5-hour observation; the light curves typically show a systematic downward ramp that is strongest for the first 30 minutes, but continues to decay for hours; from 10.6-11.8 microns, the ramp effect has remarkably different behavior, possibly due to a different illumination history for the affected region of the detector; after trimming the integrations most affected by the initial ramps and correcting the remaining systematics with analytic models, we obtain residuals to the light-curve fits that are typically within 25% of the photon noise limit for 0.5-micron spectroscopic bins; non-linearity correction is not a significant source of additional noise for WASP-43, though it may be an issue for brighter targets; the gain value of 5.5 electrons/DN currently on CRDS and JDox is known to be incorrect, and the current best estimate for the gain is approximately 3.1 electrons/DN; new reference files for the JWST calibration pipeline reflecting these findings are under development at STScI.

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T. Bell, L. Kreidberg, S. Kendrew, et. al.
Wed, 18 Jan 23
14/133

Comments: N/A

Repurposing ROACH-1 boards for prototyping of readout systems for optical-NIR MKIDs [IMA]

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http://arxiv.org/abs/2301.06893


Microwave Kinetic Inductance Detectors (MKIDs) are cryogenic photon detectors and are attractive because they permit simultaneous time, energy and spatial resolution of faint astronomical sources. We present a cost-effective alternative to dedicated (e.g. analogue) electronics for prototyping readout of single-pixel Optical/NIR MKIDs by repurposing existing and well-known ROACH-1 boards. We also present a pipeline that modernises previously-developed software and data frameworks to allow for extensiblity to new applications and portability to new hardware (e.g. Xilinx ZCU111 or 2×2 RFSoC boards).

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O. Creaner, C. Bracken, J. Piercy, et. al.
Wed, 18 Jan 23
20/133

Comments: 7 pages, 4 figures, Presented at SPIE Astronomical Telescopes + Instrumentation, 2022, Montr\’eal, Qu\’ebec, Canada

Antennas for the Low frequency radio telescope of SKA — A brief review [IMA]

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http://arxiv.org/abs/2301.06708


The low-frequency radio telescope of the Square kilometre Array (SKA) is being built by the international radio astronomical community to i) have orders of magnitude higher sensitivity and ii) be able to map the sky several hundred times faster, than any other existing facilities over the frequency range 50 MHz to 350 MHz. The sensitivity of a radio telescope array is in general dependent upon the number of electromagnetic sensors used to receive the sky signal. The total number of them is further constrained by the effects of mutual coupling between the sensor elements, allowable grating lobes in their radiation patterns etc. The operating frequency band is governed by the desired spatial and spectral response, acceptable sidelobe and backlobe levels, radiation efficiency, polarization purity and calibratability of sensors’ response. This paper presents a brief review of several broadband antennas considered as potential candidates by various engineering groups across the globe, for the low frequency radio telescope of SKA covering the frequency range of 50-350 MHz, on the basis of their suitability for conducting primary scientific objectives.

Read this paper on arXiv…

A. Raghunathan, K. Satish, A. Sathyamurthy, et. al.
Wed, 18 Jan 23
24/133

Comments: 14 pages, 33 figures, JoAA – Special issue on the SKA (2023) – Accepted for publication

Microlensing sheds light on the detection of strong lensing gravitational waves [IMA]

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http://arxiv.org/abs/2301.06117


The strong lensing gravitational wave (SLGW) is a promising transient phenomenon containing rich physics. However, the poor sky localization due to the long-wave nature of gravitational waves makes the identification of such events very challenging. We propose a new method based on the wave optics effect of the microlensing field embedded in SLGW data. The microlensing diffraction/interference fringes can produce frequency-dependent random fluctuations in the waveform. To pin down the microlensing induced stochastic features in the waveform, we utilize both the template-independent method, \texttt{cWB}, and the template-dependent method, \texttt{Bilby}, to reconstruct the waveform with and without microlensing imprints. The mismatching degree of these two waveforms can be treated as an indicator of SLGW events. We forecast the identification rate of this method with the third-generation gravitational wave observatory, such as Cosmic Explorer. Our result shows that this method can successfully identify about 2 (out of 180) SLGW events with strong enough microlensing effect per year. This method is entirely data-driven, which is immune to model priors, and can greatly avoid the false positive errors contaminated by the coincident unlensed events.

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X. Shan, X. Chen, B. Hu, et. al.
Wed, 18 Jan 23
29/133

Comments: 6 pages, 2 figures, 1 table. Comments are welcome

Towards Quantum Telescopes: Demonstration of a Two-Photon Interferometer for Quantum-Assisted Astronomy [IMA]

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http://arxiv.org/abs/2301.07042


Optical Very-Long-Baseline Interferometers (VLBI), widely used in astronomy, require phase-stable optical links across stations, which impose a limit on baseline distances, and, in turn, limits measurement precision. Here we describe a novel type of two-photon quantum-assisted interferometer, which may allow improvements in precision by orders of magnitude benefiting numerous fields in cosmology and astrophysics. We tested a tabletop version of the interferometer and unambiguously observe correlated behavior in detections of photon pairs from two thermal light sources, in agreement with theoretical predictions. This work opens new possibilities in astronomical measurements.

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J. Crawford, D. Dolzhenko, M. Keach, et. al.
Wed, 18 Jan 23
35/133

Comments: N/A

The Breakthrough Listen Search for Intelligent Life: A Laser Search Pipeline for the Automated Planet Finder [IMA]

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http://arxiv.org/abs/2301.06971


The Search for Extraterrestrial Intelligence (SETI) has traditionally been conducted at radio wavelengths, but optical searches are well-motivated and increasingly feasible due to the growing availability of high-resolution spectroscopy. We present a data analysis pipeline to search Automated Planet Finder (APF) spectroscopic observations from the Levy Spectrometer for intense, persistent, narrow bandwidth optical lasers. We describe the processing of the spectra, the laser search algorithm, and the results of our laser search on 1983 spectra of 388 stars as part of the Breakthrough Listen search for technosignatures. We utilize an empirical spectra-matching algorithm called SpecMatch-Emp to produce residuals between each target spectrum and a set of best-matching catalog spectra, which provides the basis for a more sensitive search than previously possible. We verify that SpecMatch-Emp performs well on APF-Levy spectra by calibrating the stellar properties derived by the algorithm against the SpecMatch-Emp library and against Gaia catalog values. We leverage our unique observing strategy, which produces multiple spectra of each target per night of observing, to increase our detection sensitivity by programmatically rejecting events which do not persist between observations. With our laser search algorithm we achieve a sensitivity equivalent to the ability to detect an 84 kW laser at the median distance of a star in our dataset (78.5 ly). We present the methodology and vetting of our laser search, finding no convincing candidates consistent with potential laser emission in our target sample.

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A. Zuckerman, Z. Ko, H. Isaacson, et. al.
Wed, 18 Jan 23
39/133

Comments: 24 pages, 12 figures. Accepted to The Astronomical Journal

High-angular resolution and high-contrast VLTI observations from Y to L band with the Asgard instrumental suite [IMA]

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http://arxiv.org/abs/2301.06518


The Very Large Telescope Interferometer is one of the most proficient observatories in the world for high angular resolution. Since its first observations, it has hosted several interferometric instruments operating in various bandwidths in the infrared. As a result, the VLTI has yielded countless discoveries and technological breakthroughs. Here, we introduce a new concept for the VLTI, Asgard: an instrumental suite comprised of four natively collaborating instruments: BIFROST, a combiner whose main science case is studying the formation processes and properties of stellar and planetary systems; NOTT, a nulling interferometer dedicated to imaging young nearby planetary systems in the L band; HEIMDALLR, an all-in-one instrument performing both fringe tracking and stellar interferometry with the same optics; Baldr, a Strehl optimiser. These instruments share common goals and technologies. The goals are diverse astrophysical cases such as the study of the formation and evolution processes of binary systems, exoplanetary systems and protoplanetary disks, the characterization of orbital parameters and spin-orbit alignment of multiple systems, the characterization of the exoplanets, and the study of exozodiacal disks. Thus, the idea of this suite is to make the instruments interoperable and complementary to deliver unprecedented sensitivity and accuracy from the J to M bands to meet these goals. The interoperability of the Asgard instruments and their integration in the VLTI are major challenges for this project.

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M. Martinod, D. Defrère, M. Ireland, et. al.
Wed, 18 Jan 23
54/133

Comments: N/A

Progression of Digital-Receiver Architecture: From MWA to SKA1-Low,and beyond [IMA]

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http://arxiv.org/abs/2301.06707


Backed by advances in digital electronics, signal processing, computation, and storage technologies, aperture arrays, which had strongly influenced the design of telescopes in the early years of radio astronomy, have made a comeback. Amid all these developments, an international effort to design and build the world’s largest radio telescope, the Square Kilometre Array (SKA), is ongoing. With its vast collecting area of 1 sq-km, the SKA is envisaged to provide unsurpassed sensitivity and leverage technological advances to implement a complex receiver to provide a large field of view through multiple beams on the sky. Many pathfinders and precursor aperture array telescopes for the SKA, operating in the frequency range of 10-300 MHz, have been constructed and operationalized to obtain valuable feedback on scientific, instrumental, and functional aspects. This review article looks explicitly into the progression of digital-receiver architecture from the Murchison Widefield Array (precursor) to the SKA1-Low. It highlights the technological advances in analog-to-digital converters (ADCs),field-programmable gate arrays (FPGAs), and central processing unit-graphics processing unit (CPU-GPU) hybrid platforms around which complex digital signal processing systems implement efficient channelizers, beamformers, and correlators. The article concludes with a preview of the design of a new generation signal processing platform based on radio frequency system-on-chip (RFSoC).

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G. S., H. S., S. Sethi, et. al.
Wed, 18 Jan 23
87/133

Comments: 18 pages, 4 figures, Accepted for publication in the special issue (2023) on the SKA from the JoAA

Introducing the Condor Array Telescope. 1. Motivation, Configuration, and Performance [IMA]

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http://arxiv.org/abs/2301.06301


The “Condor Array Telescope” or “Condor” is a high-performance “array telescope” comprised of six apochromatic refracting telescopes of objective diameter 180 mm, each equipped with a large-format, very low-read-noise ($\approx 1.2$ e$^-$), very rapid-read-time ($< 1$ s) CMOS camera. Condor is located at a very dark astronomical site in the southwest corner of New Mexico, at the Dark Sky New Mexico observatory near Animas, roughly midway between (and more than 150 km from either) Tucson and El Paso. Condor enjoys a wide field of view ($2.29 \times 1.53$ deg$^2$ or 3.50 deg$^2$), is optimized for measuring both point sources and extended, very low-surface-brightness features, and for broad-band images can operate at a cadence of 60 s (or even less) while remaining sky-noise limited with a duty cycle near 100\%. In its normal mode of operation, Condor obtains broad-band exposures of exposure time 60 s over dwell times spanning dozens or hundreds of hours. In this way, Condor builds up deep, sensitive images while simultaneously monitoring tens or hundreds of thousands of point sources per field at a cadence of 60 s. Condor is also equipped with diffraction gratings and with a set of He II 468.6 nm, [O III] 500.7 nm, He I 587.5 nm, H$\alpha$ 656.3 nm, [N II] 658.4 nm, and [S II] 671.6 nm narrow-band filters, allowing it to address a variety of broad- and narrow-band science issues. Given its unique capabilities, Condor can access regions of “astronomical discovery space” that have never before been studied. Here we introduce Condor and describe various aspects of its performance.

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K. Lanzetta, S. Gromoll, M. Shara, et. al.
Wed, 18 Jan 23
88/133

Comments: 23 pages, 16 figures

Sky Subtraction in an Era of Low Surface Brightness Astronomy [IMA]

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http://arxiv.org/abs/2301.05793


The Vera C. Rubin Observatory Wide-Fast Deep (WFD) sky survey will reach unprecedented surface brightness depths over tens of thousands of square degrees. Surface brightness photometry has traditionally been a challenge. Current algorithms which combine object detection with sky estimation systematically over-subtract the sky, biasing surface brightness measurements at the faint end and destroying or severely compromising low surface brightness light. While it has recently been shown that properly accounting for undetected faint galaxies and the wings of brighter objects can in principle recover a more accurate sky estimate, this has not yet been demonstrated in practice. Obtaining a consistent spatially smooth underlying sky estimate is particularly challenging in the presence of representative distributions of bright and faint objects. In this paper we use simulations of crowded and uncrowded fields designed to mimic Hyper Suprime-Cam data to perform a series of tests on the accuracy of the recovered sky. Dependence on field density, galaxy type and limiting flux for detection are all considered. Several photometry packages are utilised: Source Extractor, Gnuastro, and the LSST Science Pipelines. Each is configured in various modes, and their performance at extreme low surface brightness analysed. We find that the combination of the Source Extractor software package with novel source model masking techniques consistently produce extremely faint output sky estimates, by up to an order of magnitude, as well as returning high fidelity output science catalogues.

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L. Kelvin, I. Hasan and J. Tyson
Wed, 18 Jan 23
103/133

Comments: Accepted for publication in MNRAS. 41 pages: 9 figures and 1 table in the main text, 11 figures and 2 tables in the appendix

Performance of the RF-detectors of the Astroneu Array [IMA]

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http://arxiv.org/abs/2301.06867


Since 2014, the University Campus of the Hellenic Open University (HOU) hosts the Astroneu array which is dedicated to the detection of Extensive Air Showers (EAS) induced by high energy Cosmic Rays (CR). The Astroneu array incorporates 9 large particle scintillation detectors and 6 antennas sensitive in the Radio Frequency (RF) range 1-200 MHz. The detectors are adjusted in three autonomous stations operating in an environment with strong electromagnetic background. As shown by previous studies, EAS radio detection in such environments is possible using innovative noise rejection methods, as well as advanced analysis techniques. In this work, we present the analysis of the collected radio data corresponding to an operational period of approximately four years. We present the performance of the Astroneu radio array in reconstructing the EAS axis direction using different RF detector geometrical layouts and a technique for the estimation of the shower core by comparing simulation and experimental data. Moreover, we measure the relative amplitudes of the two mechanisms that give rise to RF emission (Askaryan effect and Geomagnetic emission) and show that they are in good agreement with previous studies as well as with the simulation predictions.

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S. Nonis, A. Leisos, A. Tsirigotis, et. al.
Wed, 18 Jan 23
108/133

Comments: 26 pages, 11 figures

Reaching sub-millisecond accuracy in stellar occultations and artificial satellites tracking [IMA]

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http://arxiv.org/abs/2301.06378


In recent years there appeared a need for astronomical observations timed with sub-millisecond accuracy. These include e.g. timing stellar occultations by small, sub-km or fast Near Earth Asteroids, but also tracking artificial satellites at Low Earth Orbit using optical sensors. Precise astrometry of fast-moving satellites, and accurate timing of stellar occultations have parallel needs, requiring reliable time source and good knowledge of camera delays. Thus a need for an external device that would enable equipment and camera testing, to check if they reach the required accuracy in time. We designed, constructed and thoroughly tested a New EXposure Timing Analyser (NEXTA): a GNSS-based precise timer (Global Navigation Satellite System), allowing to reach the accuracy of 0.1 millisecond, which is an order of magnitude better than in previously available tools. The device is a simple strip of blinking diodes, to be imaged with a camera under test and compare imaged time with internal camera time stamp. Our tests spanned a range of scientific cameras widely used for stellar occultations and ground-based satellite tracking. The results revealed high reliability of both NEXTA and most of the tested cameras, but also pointed that practically all cameras had internal time bias of various level. NEXTA can serve the community, being easily reproducible with inexpensive components. We provide all the necessary schemes and usage instructions.

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K. Kamiński, C. Weber, A. Marciniak, et. al.
Wed, 18 Jan 23
117/133

Comments: 33 pages, 27 figures, 4 tables, Accepted to PASP

Low-rank plus sparse trajectory decomposition for direct exoplanet imaging [IMA]

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http://arxiv.org/abs/2301.07018


We propose a direct imaging method for the detection of exoplanets based on a combined low-rank plus structured sparse model. For this task, we develop a dictionary of possible effective circular trajectories a planet can take during the observation time, elements of which can be efficiently computed using rotation and convolution operation. We design a simple alternating iterative hard-thresholding algorithm that jointly promotes a low-rank background and a sparse exoplanet foreground, to solve the non-convex optimisation problem. The experimental comparison on the $\beta$-Pictoris exoplanet benchmark dataset shows that our method has the potential to outperform the widely used Annular PCA for specific planet light intensities in terms of the Receiver operating characteristic (ROC) curves.

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S. Vary, H. Daglayan, L. Jacques, et. al.
Wed, 18 Jan 23
120/133

Comments: 5 pages, 4 figures, ICASSP 2023

MeerKAT Holography Measurements in the UHF, L, and S bands [IMA]

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http://arxiv.org/abs/2301.06752


Radio holographic measurements using the MeerKAT telescope are presented for each of its supported observing bands, namely UHF (544–1087 MHz), L (856–1711 MHz) and S (1750–3499 MHz). Because the UHF-band receiver design is a scaled version of that of the L band, the electromagnetic performance in these two bands are expectedly similar to one another. Despite also being linearly polarized, S-band receivers have an entirely different design and distinct performance characteristics from the lower two bands. As introduced in previous work for the L band, evidence of higher-order waveguide mode activation also appears in S-band measurements but there are differences in its manifestation. Frequency-dependent pointing (beam squint), beam width, beam ellipticity, errorbeam, instrumental polarization and cross-polarization power measurements are illustrated for each of MeerKAT’s observational bands in a side-by-side style to facilitate the comparison of features. The derivation of collimation errors and main reflector surface errors from measurements made at these relatively low observation frequencies is also discussed. Results include elevation and ambient temperature effects on collimation, as well as the signatures of collimation degrading over time. The accompanying data release includes a snapshot of full Jones matrix primary beam patterns for all bands and antennas, with corresponding derived metrics.

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M. Villiers
Wed, 18 Jan 23
133/133

Comments: 20 pages, 13 figures, 4 tables

UK Astronomy Science and Technology Roadmap: STFC Astronomy Advisory Panel Roadmap 2022 [IMA]

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http://arxiv.org/abs/2301.05457


This document summarises the UK astronomy community’s science and technology priorities for funding and investments in the coming decades, following a series of national community consultations by the Astronomy Advisory Panel of the Science and Technology Facilities Council (STFC). The facility remit of STFC is ground-based so the infrastructure recommendations are necessarily also ground-based, but the report also recognises the importance of STFC-funded technology development for, and science exploitation of, the ESA science program including but not limited to X-ray, gamma-ray and multimessenger astronomy.

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S. Serjeant, J. Bolton, P. Gandhi, et. al.
Mon, 16 Jan 23
43/50

Comments: 37 pages plus cover. Also available at the UKRI website this https URL

UK Astronomy Science and Technology Roadmap: STFC Astronomy Advisory Panel Roadmap 2022 [IMA]

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http://arxiv.org/abs/2301.05457


This document summarises the UK astronomy community’s science and technology priorities for funding and investments in the coming decades, following a series of national community consultations by the Astronomy Advisory Panel of the Science and Technology Facilities Council (STFC). The facility remit of STFC is ground-based so the infrastructure recommendations are necessarily also ground-based, but the report also recognises the importance of STFC-funded technology development for, and science exploitation of, the ESA science program including but not limited to X-ray, gamma-ray and multimessenger astronomy.

Read this paper on arXiv…

S. Serjeant, J. Bolton, P. Gandhi, et. al.
Mon, 16 Jan 23
20/50

Comments: 37 pages plus cover. Also available at the UKRI website this https URL

Optimal filtering techniques for the adaptive optics system of the LBT [IMA]

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http://arxiv.org/abs/2301.05165


In this paper we will discuss the application of optimal filtering techniques for the adaptive optics system of the LBT telescope. We have studied the application of both Kalman and H$\infty$ filters to estimate the temporal evolution of the phase perturbations due to the atmospheric turbulence and the telescope vibrations on tip/tilt modes. We will focus on the H$\infty$ filter and on its advantages and disadvantages over the Kalman filter.

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G. Agapito, F. Quirós-Pacheco, P. Tesi, et. al.
Fri, 13 Jan 23
10/72

Comments: 6 pages, 6 figures, 3 tables, European Control Conference (ECC) 2009, Budapest, Hungary, August 23-26, 2009

Full non-LTE spectral line formation II. Two-distribution radiation transfer with coherent scattering in the atom's frame [IMA]

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http://arxiv.org/abs/2301.04924


In the present article, we discuss a numerical method of solution for the so-called “full non-LTE” radiation transfer problem, basic formalism of which was revisited by Paletou & Peymirat (2021; see also Oxenius 1986). More specifically, usual numerical iterative methods for non-LTE radiation transfer are coupled with the above-mentioned formalism. New numerical additions are explained in detail. We benchmark the whole process with the standard non-LTE transfer problem for a two-level atom with Hummer’s (1962, 1969) $R_{\rm I-A}$ partial frequency redistribution function. We finally display new quantities such as the spatial distribution of the velocity distribution function of excited atoms, that can only be accessed to by adopting this more general frame for non-LTE radiation transfer.

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F. Paletou, M. Sampoorna and C. Peymirat
Fri, 13 Jan 23
18/72

Comments: 7 pages, 5 figures, accepted A&A

Intensity Interferometry observations of the H$α$ envelope of $γ$ Cas with MéO and a portable telescope [IMA]

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http://arxiv.org/abs/2301.04878


We report on observations of the extended environment of the bright Be star $\gamma$-Cas performed using intensity interferometry measurements within its H$\alpha$ emission line. These observations were performed using a modified version of the I2C intensity interferometry instrument installed onto the 1.54 meter M\'{e}O optical metrology telescope and a portable 1-meter telescope (T1M). In order to better constrain the extent of the H$\alpha$ envelope, observations were performed for two different positions of the T1M telescope, corresponding to an intermediate and long baselines in which the extended region was partially and fully resolved. We find that the observed data are consistent with past interferometric observations of $\gamma$-Cas. These observations demonstrate the capability to equip optical telescopes of different optical designs with intensity interferometry capabilities and illustrate the potential to scale a similar system onto many additional telescopes.

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N. Matthews, J. Rivet, D. Vernet, et. al.
Fri, 13 Jan 23
34/72

Comments: N/A

Robust Construction of DEM Profiles and Maps from AIA data using a Regularized Maximum Likelihood Method [IMA]

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http://arxiv.org/abs/2301.04688


Aims. To introduce and develop a Regularized Maximum Likelihood (RML) algorithm designed to address the mathematically ill-posed problem of constructing differential emission measure profiles from a discrete set of EUV intensities in specified wavelength bands, specifically those observed by the Atmospheric Imaging Assembly (AIA) on the NASA Solar Dynamics Observatory. Methods. RML combines features of Maximum Likelihood and regularized approaches used by other authors. It is also guaranteed to produce a positive definite differential emission measure profile. Results. We evaluate and compare the effectiveness of the method against other published algorithms, using both simulated data generated from parametric differential emission profile forms, and AIA data from a solar eruptive event on 2010 November 3. Similarities and differences between the differential emission measure profiles and maps reconstructed by the various algorithms are discussed. Conclusions. The RML inversion method is mathematically rigorous, computationally efficient, and robust in the presence of data noise. As such it shows considerable promise for computing differential emission measure profiles from datasets of discrete spectral lines.

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P. Massa, A. Emslie, I. Hannah, et. al.
Fri, 13 Jan 23
47/72

Comments: N/A

Science Priorities for the Extraction of the Solid MSR Samples from their Sample Tubes [IMA]

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http://arxiv.org/abs/2301.04694


Preservation of the chemical and structural integrity of samples that will be brought back from Mars is paramount to achieving the scientific objectives of MSR. Given our knowledge of the nature of the samples retrieved at Jezero by Perseverance, at least two options need to be tested for opening the sample tubes: (1) One or two radial cuts at the end of the tube to slide the sample out. (2) Two radial cuts at the ends of the tube and two longitudinal cuts to lift the upper half of the tube and access the sample. Strategy 1 will likely minimize contamination but incurs the risk of affecting the physical integrity of weakly consolidated samples. Strategy 2 will be optimal for preserving the physical integrity of the samples but increases the risk of contamination and mishandling of the sample as more manipulations and additional equipment will be needed. A flexible approach to opening the sample tubes is therefore required, and several options need to be available, depending on the nature of the rock samples returned. Both opening strategies 1 and 2 may need to be available when the samples are returned to handle different sample types (e.g., loosely bound sediments vs. indurated magmatic rocks). This question should be revisited after engineering tests are performed on analogue samples. The MSR sample tubes will have to be opened under stringent BSL4 conditions and this aspect needs to be integrated into the planning.

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N. Dauphas, S. Russell, D. Beaty, et. al.
Fri, 13 Jan 23
50/72

Comments: 8 pages, 3 figures, 1 table, report NASA-ESA Mars Rock Team Report

Techniques for Measuring Parallax and Proper Motion with VLBI [IMA]

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http://arxiv.org/abs/2301.04756


Astrometry at centimeter wavelengths using Very Long Baseline Interferometry is approaching accuracies of ~1 uas for the angle between a target and a calibrator source separated by <1 degree on the sky. The BeSSeL Survey and the Japanese VERA project are using this to map the spiral structure of the Milky Way by measuring trigonometric parallaxes of hundreds of maser sources associated with massive, young stars. This paper outlines how micro-arcsecond astrometry is done, including details regarding the scheduling of observations, calibration of data, and measuring positions.

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M. Reid
Fri, 13 Jan 23
61/72

Comments: 18 pages; 5 figures

Pixelated Reconstruction of Foreground Density and Background Surface Brightness in Gravitational Lensing Systems using Recurrent Inference Machines [IMA]

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http://arxiv.org/abs/2301.04168


Modeling strong gravitational lenses in order to quantify the distortions in the images of background sources and to reconstruct the mass density in the foreground lenses has been a difficult computational challenge. As the quality of gravitational lens images increases, the task of fully exploiting the information they contain becomes computationally and algorithmically more difficult. In this work, we use a neural network based on the Recurrent Inference Machine (RIM) to simultaneously reconstruct an undistorted image of the background source and the lens mass density distribution as pixelated maps. The method iteratively reconstructs the model parameters (the image of the source and a pixelated density map) by learning the process of optimizing the likelihood given the data using the physical model (a ray-tracing simulation), regularized by a prior implicitly learned by the neural network through its training data. When compared to more traditional parametric models, the proposed method is significantly more expressive and can reconstruct complex mass distributions, which we demonstrate by using realistic lensing galaxies taken from the IllustrisTNG cosmological hydrodynamic simulation.

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A. Adam, L. Perreault-Levasseur, Y. Hezaveh, et. al.
Thu, 12 Jan 23
2/68

Comments: 13+7 pages, 13 figures; Submitted to The Astrophysical Journal. arXiv admin note: text overlap with arXiv:2207.01073

A Global Radio Remote Sensing Network for Observing Space Weather Dynamics [IMA]

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http://arxiv.org/abs/2301.04137


Our current sampling of the near-Earth space environment is wholly insufficient to measure the highly variable processes therein and make predictions on par with lower atmospheric weather. We sketch out the scientific rationale for a network of radio instruments delivering dense observations of the near-Earth space environment and the broad steps necessary to implement wide-scale coverage in the next 30 years.

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R. Volz, P. Erickson, S. Palo, et. al.
Thu, 12 Jan 23
11/68

Comments: Heliophysics 2050 Workshop

Radio Interferometer with Simple antennas [IMA]

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http://arxiv.org/abs/2301.04271


A Radio interferometer comprises several antennas, spared over a large area. Say ALMA(Atacama Large Millimeter/submillimeter Array), VLA(very large array), VLBA(Very Long Baseline Array), GMRT(Giant Metrewave Radio Telescope), MWA( Murchison Widefield Array), EHT(Event Horizon Telescope), and the SKA(Square Kilometer Array), the name itself speaks about square-kilometres of area. Most radio observatories are constructed or constitute giant dish antennas, and few constitute an extensive array of antennas. However, what if a simple antenna like Dipole, Loop or Yagi-UDA is considered an element of an interferometer? Then how does it affect the visibility of the instrument? Yes, it will be less, but how weak? Furthermore, what is the math to reach it? These questions pushed for this work. Here, one can find the detailed derivation starting from a simple Young’s double slit experiment to a radio interferometer intensity distribution in terms of the Gain of the antenna element. This literature aided in understanding the interferometer of yagi antennas of Gain 11dBi, resulting in a visibility of 0.0714. This clarity was insignificant in the current work. Hence using this work, one can design and construct a suited interferometer for their requirement.

Read this paper on arXiv…

A. Kulkarni
Thu, 12 Jan 23
13/68

Comments: N/A

A Characterization of the ALMA Phasing System at 345 GHz [IMA]

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http://arxiv.org/abs/2301.04543


The development of the Atacama Large Millimeter/submillimeter Array (ALMA) phasing system (APS) has allowed ALMA to function as an extraordinarily sensitive station for very long baseline interferometry (VLBI) at frequencies of up to 230 GHz (~1.3 mm). Efforts are now underway to extend use of the APS to 345 GHz (~0.87 mm). Here we report a characterization of APS performance at 345 GHz based on a series of tests carried out between 2015-2021, including a successful global VLBI test campaign conducted in 2018 October in collaboration with the Event Horizon Telescope (EHT).

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G. Crew, C. Goddi, L. Matthews, et. al.
Thu, 12 Jan 23
15/68

Comments: 22 pages, 11 figures, 7 tables, accepted for publication in PASP

Focused Space Weather Strategy for Securing Earth, and Human Exploration of the Moon and Mars [IMA]

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http://arxiv.org/abs/2301.04136


This white paper recognizes gaps in observations that will, when addressed, much improve solar radiation hazard and geomagnetic storm forecasting. Radiation forecasting depends on observations of the entire “Solar Radiation Hemisphere” that we will define. Mars exploration needs strategic placement of radiation-relevant observations. We also suggest an orbital solution that will improve geomagnetic storm forecasting through improved in situ and solar/heliospheric remote sensing.

Read this paper on arXiv…

A. Posner, N. Arge, K. Cho, et. al.
Thu, 12 Jan 23
26/68

Comments: Heliophysics 2050 White Paper

Trajectory Based RFI Subtraction and Calibration for Radio Interferometry [IMA]

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http://arxiv.org/abs/2301.04188


Radio interferometry calibration and Radio Frequency Interference (RFI) removal are usually done separately. Here we show that jointly modelling the antenna gains and RFI has significant benefits when the RFI follows precise trajectories, such as for satellites. One surprising benefit is improved calibration solutions, by leveraging the RFI signal itself. We present TABASCAL (TrAjectory BAsed RFI Subtraction and CALibration), a new algorithm that jointly models the RFI signal & trajectory as well as the calibration parameters in post-correlation visibilities. TABASCAL can use either optimisation or fully Bayesian statistical methods to find calibration solutions in contaminated data that would otherwise be thrown away. We test TABASCAL on simulated MeerKAT calibration observations contaminated by satellite-based RFI with amplitudes varying between -20 dB and 15 dB relative to a 1 Jy source. We obtain gain estimates that are both unbiased and up to an order of magnitude better constrained compared to the case of no RFI. TABASCAL can be further applied to an adjacent target observation: using 5 minutes of calibration data resulted in an image with about half the noise compared to using purely flagged data, and only 23% higher than an uncontaminated observation. The source detection threshold and recovered flux distribution of TABASCAL-processed data was on par with uncontaminated data. In contrast, RFI flagging alone resulted in consistent underestimation of source fluxes and less sources detected. For a mean RFI amplitude of 17 Jy, using TABASCAL leads to less than 1% loss of data compared to 75% data loss from ideal $3\sigma$ flagging, a significant increase in data available for science analysis. Although we have examined the case of satellite RFI, TABASCAL should work for any RFI moving on parameterizable trajectories, such as planes or objects fixed to the ground.

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C. Finlay, B. Bassett, M. Kunz, et. al.
Thu, 12 Jan 23
27/68

Comments: 19 pages, 16 figures, 4 tables

Low-Frequency Noise Mitigation and Bandgap Engineering using Seismic Metamaterials for Terrestrial Gravitational Wave Observatories [IMA]

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http://arxiv.org/abs/2301.04325


Gravitational-wave now became one of the important observational methods for studying the Universe since its first detection. However, the ground-based observatories have an inherent barrier to their detection frequency band due to the seismic and gravity gradient noises nearby the perturbation of the surroundings. A recent intriguing development of artificial structures for media called metamaterial is opening a new branch of wave mechanics and its application in various fields, in particular, suggesting a novel way of mitigating noises by controlling the media structure for propagating waves. In this paper, we propose a novel framework for handling noises in ground-based gravitational wave detectors by using wave mechanics under metamaterial media. Specifically, we suggest an application of the bandgap engineering technique for mitigating the underground effects of acoustic noises resulting from the seismic vibration in the KAGRA gravitational wave observatory.

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J. Oh
Thu, 12 Jan 23
42/68

Comments: 7pages, 5figures

Hint assisted reinforcement learning: an application in radio astronomy [IMA]

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http://arxiv.org/abs/2301.03933


Model based reinforcement learning has proven to be more sample efficient than model free methods. On the other hand, the construction of a dynamics model in model based reinforcement learning has increased complexity. Data processing tasks in radio astronomy are such situations where the original problem which is being solved by reinforcement learning itself is the creation of a model. Fortunately, many methods based on heuristics or signal processing do exist to perform the same tasks and we can leverage them to propose the best action to take, or in other words, to provide a hint'. We propose to usehints’ generated by the environment as an aid to the reinforcement learning process mitigating the complexity of model construction. We modify the soft actor critic algorithm to use hints and use the alternating direction method of multipliers algorithm with inequality constraints to train the agent. Results in several environments show that we get the increased sample efficiency by using hints as compared to model free methods.

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S. Yatawatta
Wed, 11 Jan 23
43/80

Comments: N/A

Constraining cosmological parameters from N-body simulations with Variational Bayesian Neural Networks [IMA]

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http://arxiv.org/abs/2301.03991


Methods based on Deep Learning have recently been applied on astrophysical parameter recovery thanks to their ability to capture information from complex data. One of these methods is the approximate Bayesian Neural Networks (BNNs) which have demonstrated to yield consistent posterior distribution into the parameter space, helpful for uncertainty quantification. However, as any modern neural networks, they tend to produce overly confident uncertainty estimates and can introduce bias when BNNs are applied to data. In this work, we implement multiplicative normalizing flows (MNFs), a family of approximate posteriors for the parameters of BNNs with the purpose of enhancing the flexibility of the variational posterior distribution, to extract $\Omega_m$, $h$, and $\sigma_8$ from the QUIJOTE simulations. We have compared this method with respect to the standard BNNs, and the flipout estimator. We found that MNFs combined with BNNs outperform the other models obtaining predictive performance with almost one order of magnitude larger that standard BNNs, $\sigma_8$ extracted with high accuracy ($r^2=0.99$), and precise uncertainty estimates. The latter implies that MNFs provide more realistic predictive distribution closer to the true posterior mitigating the bias introduced by the variational approximation and allowing to work with well-calibrated networks.

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H. Hortúa, L. García and L. C
Wed, 11 Jan 23
52/80

Comments: 15 pages, 4 figures, 3 tables, submitted. Comments welcome

Commission Femmes et Astronomie de la SF2A: Women participation in French astronomy [IMA]

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http://arxiv.org/abs/2301.03658


The Commission Femmes et Astronomie conducted a statistical study that aims at mapping the presence of women in French professional Astronomy today, and set a starting point for studying its evolution with time. For the year 2021, we proceeded with a sub-set of 8 astronomy and astrophysics institutes, hosting a total of 1060 employees, among which PhD students, post-doctoral researchers, and academic, technical, and administrative staff, representing around 25% of the community. We have investigated how the percentage of women vary with career stage, level of responsibility, job security, and level of income. The results of this preliminary study seem to illustrate the leaky pipeline, with one major bottleneck being the access to permanent positions. It appears that the proportion of women steadily decreases with the security of jobs, with the career stage, with the qualification level and with the income level.

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R. Ouazzani, C. Bot, S. Brau-Nogué, et. al.
Wed, 11 Jan 23
55/80

Comments: 6 pages, 5 figures

The Cosmological Simulation Code OpenGadget3 — Implementation of Meshless Finite Mass [IMA]

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http://arxiv.org/abs/2301.03612


Subsonic turbulence plays a major role in determining properties of the intra cluster medium (ICM). We introduce a new Meshless Finite Mass (MFM) implementation in OpenGadget3 and apply it to this specific problem. To this end, we present a set of test cases to validate our implementation of the MFM framework in our code. These include but are not limited to: the soundwave and Kepler disk as smooth situations to probe the stability, a Rayleigh-Taylor and Kelvin-Helmholtz instability as popular mixing instabilities, a blob test as more complex example including both mixing and shocks, shock tubes with various Mach numbers, a Sedov blast wave, different tests including self-gravity such as gravitational freefall, a hydrostatic sphere, the Zeldovich-pancake, and the nifty cluster as cosmological application. Advantages over SPH include increased mixing and a better convergence behavior. We demonstrate that the MFM-solver is robust, also in a cosmological context. We show evidence that the solver preforms extraordinarily well when applied to decaying subsonic turbulence, a problem very difficult to handle for many methods. MFM captures the expected velocity power spectrum with high accuracy and shows a good convergence behavior. Using MFM or SPH within OpenGadget3 leads to a comparable decay in turbulent energy due to numerical dissipation. When studying the energy decay for different initial turbulent energy fractions, we find that MFM performs well down to Mach numbers $\mathcal{M}\approx 0.007$. Finally, we show how important the slope limiter and the energy-entropy switch are to control the behavior and the evolution of the fluids.

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F. Groth, U. Steinwandel, M. Valentini, et. al.
Wed, 11 Jan 23
68/80

Comments: 27 pages, 24 figures, submitted to MNRAS

TESS-Gaia Light Curve: a PSF-based TESS FFI light curve product [IMA]

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http://arxiv.org/abs/2301.03704


The Transiting Exoplanet Survey Satellite (TESS) is continuing its second extended mission after 55 sectors of observations. TESS publishes full-frame images (FFI) at a cadence of 1800, 600, or 200 seconds, allowing light curves to be extracted for stars beyond a limited number of pre-selected stars. Simulations show that thousands of exoplanets, eclipsing binaries, variable stars, and other astrophysical transients can be found in these FFI light curves. To obtain high-precision light curves, we forward model the FFI with the effective point spread function to remove contamination from nearby stars. We adopt star positions and magnitudes from Gaia DR3 as priors. The resulting light curves, called TESS-Gaia Light Curves (TGLC), show a photometric precision closely tracking the pre-launch prediction of the noise level. TGLC’s photometric precision reaches <~2% at 16th TESS magnitude even in crowded fields. We publish TGLC Aperture and PSF light curves for stars down to 16th TESS magnitude through the Mikulski Archive for Space Telescopes (MAST) for all available sectors and will continue to deliver future light curves via DOI: 10.17909/610m-9474. The open-source package tglc is publicly available to enable any user to produce customized light curves.

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T. Han and T. Brandt
Wed, 11 Jan 23
76/80

Comments: 23 pages, 13 figures, 4 tables, AJ accepted. Light curves are available at this https URL tglc package is pip-installable and available at this https URL

FAIR solutions for a science platform to analyse Cherenkov data online [IMA]

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http://arxiv.org/abs/2301.03841


We developed a system to run quick analyses of Cherenkov data in compliance with the FAIR Guiding Principles for scientific data management (FAIR: Findable, Accessible, Interoperable and Reusable), through the use of interoperability standards and technologies, particularly those provided by the International Virtual Observatory Alliance (IVOA) to build the Virtual Observatory (VO). We therefore provide a controlled and stable environment on a computing cluster, in order to execute and re-execute well defined jobs. User-specific input parameters can be specified to configure the execution of an analysis job. Provenance information is automatically captured by the system and accessible to the user. To avoid long transfers, the data can be placed close to the computing nodes. This system is primarily used to analyse Cherenkov astronomy data, though it may be used for other purposes.

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M. Servillat, P. Kornecki and C. Boisson
Wed, 11 Jan 23
79/80

Comments: ADASS XXXII, Oct 2022, Victoria, Canada

Limiting Magnitudes of the Wide Field Survey Telescope (WFST) [IMA]

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http://arxiv.org/abs/2301.03068


Expected to be of the highest survey power telescope in the northern hemisphere, the Wide Field Survey Telescope (WFST) will begin its routine observations of the northern sky since 2023. WFST will produce a lot of scientific data to support the researches of time-domain astronomy, asteroids and the solar system, galaxy formation and cosmology and so on. We estimated that the 5 $\sigma$ limiting magnitudes of WFST with 30 second exposure are $u=22.31$ mag, $g=23.42$ mag, $r=22.95$ mag, $i=22.43$ mag, $z=21.50$ mag, $w=23.61$ mag. The above values are calculated for the conditions of $airmass=1.2$, seeing = 0.75 arcsec, precipitable water vapour (PWV) = 2.5 mm and Moon-object separation = $45^{\circ}$ at the darkest New Moon night of the Lenghu site (V=22.30 mag, Moon phase $\theta=0^{\circ}$). The limiting magnitudes in different Moon phase conditions are also calculated. The calculations are based on the empirical transmittance data of WFST optics, the vendor provided CCD quantum efficiency, the atmospherical model transmittance and spectrum of the site. In the absence of measurement data such as sky transmittance and spectrum, we use model data.

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L. Lei, Q. Zhu, X. Kong, et. al.
Tue, 10 Jan 23
6/93

Comments: 12 pages, 5 figures, accepted by RAA (Research in Astronomy and Astrophysics)

Inverse problem approach in Extreme Adaptive Optics: analytical model of the fitting error and lowering of the aliasing [IMA]

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http://arxiv.org/abs/2301.03478


We present the results obtained with an end-to-end simulator of an Extreme Adaptive Optics (XAO) system control loop. It is used to predict its on-sky performances and to optimise the AO loop algorithms. It was first used to validate a novel analytical model of the fitting error, a limit due to the Deformable Mirror (DM) shape. Standard analytical models assume a sharp correction under the DM cutoff frequency, disregarding the transition between the AO corrected and turbulence dominated domains. Our model account for the influence function shape in this smooth transition. Then, it is well-known that Shack-Hartmann wavefront sensors (SH-WFS) have a limited spatial bandwidth, the high frequencies of the wavefront being seen as low frequencies. We show that this aliasing error can be partially compensated (both in terms of Strehl ratio and contrast) by adding priors on the turbulence statistics in the framework of an inverse problem approach. This represents an alternative to the standard additional optical filter used in XAO systems. In parallel to this numerical work, a bench was aligned to experimentally test the AO system and these new algorithms comprising a DM192 ALPAO deformable mirror and a 15×15 SH-WFS. We present the predicted performances of the AO loop based on end-to-end simulations.

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A. Berdeu, M. Tallon, &. Thiébaut, et. al.
Tue, 10 Jan 23
16/93

Comments: N/A

Low-order wavefront control using a Zernike sensor through Lyot coronagraphs for exoplanet imaging: II. Concurrent operation with stroke minimization [IMA]

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http://arxiv.org/abs/2301.03242


Wavefront sensing and control (WFSC) will play a key role in improving the stability of future large segmented space telescopes while relaxing the thermo-mechanical constraints on the observatory structure. Coupled with a coronagraph to reject the light of an observed bright star, WFSC enables the generation and stabilisation of a dark hole (DH) in the star image to perform planet observations. While WFSC traditionally relies on a single wavefront sensor (WFS) input to measure wavefront errors, the next generation of instruments will require several WFSs to address aberrations with different sets of spatial and temporal frequency contents. The multiple measurements produced in such a way will then have to be combined and converted to commands for deformable mirrors (DMs) to modify the wavefront subsequently. We asynchronously operate a loop controlling the high-order modes digging a DH and a control loop that uses the rejected light by a Lyot coronagraph with a Zernike wavefront sensor to stabilize the low-order aberrations. Using the HiCAT testbed with a segmented telescope aperture, we implement concurrent operations and quantify the expected cross-talk between the two controllers. We then present experiments that alternate high-order and low-order control loops to identify and estimate their respective contributions. We show an efficient combination of the high-order and low-order control loops, keeping a DH contrast better than 5 x 10-8 over a 30 min experiment and stability improvement by a factor of 1.5. In particular, we show a contrast gain of 1.5 at separations close to the DH inner working angle, thanks to the low-order controller contribution. Concurrently digging a DH and using the light rejected by a Lyot coronagraph to stabilize the wavefront is a promising path towards exoplanet imaging and spectroscopy with future large space observatories.

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R. Pourcelot, E. Por, M. N’Diaye, et. al.
Tue, 10 Jan 23
19/93

Comments: N/A

MulGuisin, a Topological Clustering Algorithm, and Its Performance as a Cosmic Structure Finder [IMA]

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http://arxiv.org/abs/2301.03278


We introduce a new clustering algorithm, MulGuisin (MGS), that can find galaxy clusters using topological information from the galaxy distribution. This algorithm was first introduced in an LHC experiment as a Jet Finder software, which looks for particles that clump together in close proximity. The algorithm preferentially considers particles with high energies and merges them only when they are closer than a certain distance to create a jet. MGS shares some similarities with the minimum spanning tree (MST) since it provides both clustering and graph-based topology information. Also, similar to the density-based spatial clustering of applications with noise (DBSCAN), MGS uses the ranking or the local density of each particle to construct clustering. In this paper, we compare the performances of clustering algorithms using some controlled data and some realistic simulation data as well as the SDSS observation data, and we demonstrate that our new algorithm find clusters most efficiently and it defines galaxy clusters in a way that most closely resembles human vision.

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Y. Ju, I. Park, C. Sabiu, et. al.
Tue, 10 Jan 23
22/93

Comments: 14 pages,12 figures

The Haystack Telescope as an Astronomical Instrument [IMA]

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http://arxiv.org/abs/2301.02713


The Haystack Telescope is an antenna with a diameter of 37~m and an elevation-dependent surface accuracy of $\le{}100~\mu{}\rm{}m$ that is capable of millimeter-wave observations. The radome-enclosed instrument serves as a radar sensor for space situational awareness, with about one-third of the time available for research by MIT Haystack Observatory. Ongoing testing with the K-band (18-26~GHz) and W-band receivers (currently 85-93~GHz) is preparing the inclusion of the telescope into the Event Horizon Telescope (EHT) array and the use as a single-dish research telescope. Given its geographic location, the addition of the Haystack Telescope to current and future versions of the EHT array would substantially improve the image quality.

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J. Kauffmann, G. Rajagopalan, K. Akiyama, et. al.
Tue, 10 Jan 23
47/93

Comments: accepted to the ngEHT Special Issue of “Galaxies”

Radio source analysis services for the SKA and precursors [IMA]

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http://arxiv.org/abs/2301.02804


New developments in data processing and visualization are being made in preparation for upcoming radioastronomical surveys planned with the Square Kilometre Array (SKA) and its precursors. A major goal is enabling extraction of science information from the data in a mostly automated way, possibly exploiting the capabilities offered by modern computing infrastructures and technologies. In this context, the integration of source analysis algorithms into data visualization tools is expected to significantly improve and speed up the cataloguing process of large area surveys. To this aim, the CIRASA (Collaborative and Integrated platform for Radio Astronomical Source Analysis) project was recently started to develop and integrate a set of services for source extraction, classification and analysis into the ViaLactea visual analytic platform and knowledge base archive. In this contribution, we will present the project objectives and tools that have been developed, interfaced and deployed so far on the prototype European Open Science Cloud (EOSC) infrastructure provided by the H2020 NEANIAS project.

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S. Riggi, C. Bordiu, D. Magro, et. al.
Tue, 10 Jan 23
49/93

Comments: 4 pages, 3 figures, proceedings of ADASS XXXI conference, to be published in ASP Conference Series

Correction of the brighter-fatter effect on the CCDs of Hyper Suprime-Cam [IMA]

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http://arxiv.org/abs/2301.03274


The brighter-fatter effect affects all CCD sensors to various degrees. Deep-depleted thick sensors are seriously affected and the measurement of galaxy shapes for cosmic shear measurements requires an accurate correction of the effect in science images. We describe the whole correction chain we have implemented for the CCDs of the Hyper Suprime-Cam imager on the Subaru Telescope. We derive non linearity corrections from a new sequence of flat field images, and measure their statistics, namely their two-pixel function. We constrain an electrostatic model from flat field statistics that we use to correct science images. We find evidence that some fraction of the observed variance and some covariances is not due to the combination of Poisson statistics and electrostatics — and the cause remains elusive. We then have to ignore some measurements when deriving the electrostatic model. Over a wide range of image qualities and in the 5 bands of the imager, stars in corrected science images exhibit size variations with flux small enough to predict the point spread function for faint objects to an accuracy better than $10^{-3}$ for the trace of second moments — and even better for the ellipticity and the fourth radial moment. This performance is sufficient for upcoming large-scale cosmic shear surveys such as Rubin/LSST.

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P. Astier and N. Regnault
Tue, 10 Jan 23
50/93

Comments: 18 pages, 24 figures, accepted for publication in A&A

Proper evaluation of spatially correlated noise in interferometric images [IMA]

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http://arxiv.org/abs/2301.03579


Interferometers (e.g. ALMA and NOEMA) allow us to obtain the detailed brightness distribution of astronomical sources in 3 dimensions (R.A., Dec., frequency). However, the spatial correlation of the noise makes it difficult to evaluate the statistical uncertainty of the measured quantities and the statistical significance of the results obtained. The noise correlation properties in the interferometric image are fully characterized and easily measured by the noise autocorrelation function (ACF). We present the method for (1) estimating the statistical uncertainty due to the correlated noise in the spatially integrated flux and spectra directly, (2) simulating the correlated noise to perform a Monte Carlo simulation in image analyses, and (3) constructing the covariance matrix and chi-square $\chi^2$ distribution to be used when fitting a model to an image with spatially correlated noise, based on the measured noise ACF. We demonstrate example applications to scientific data showing that ignoring noise correlation can lead to significant underestimation of statistical uncertainty of the results and false detections/interpretations.

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T. Tsukui, S. Iguchi, I. Mitsuhashi, et. al.
Tue, 10 Jan 23
58/93

Comments: Accepted for publication in JATIS, 41 pages, 14 figures; Python codes are available at this https URL; Comments are warmly welcomed. arXiv admin note: substantial text overlap with arXiv:2207.12588

Confusion noise from Galactic binaries for Taiji [IMA]

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http://arxiv.org/abs/2301.02821


Gravitational waves (GWs) from tens of millions of compact binaries in our Milky Way enter the milli-Hertz band of space-based detection. The majority of them cannot be resolved individually, resulting in a foreground confusion noise for Laser Interferometer Space Antenna (LISA). The concept of Taiji mission is similar to LISA’s with slightly better sensitivity, which means that the galactic GW signals will also affect the detection with Taiji. Here we generate the GW signals from 29.8 million galactic binaries for Taiji and subtract the `resolvable’ sources. The confusion noise is estimated and fitted in an analytic form with 6-month, 1-year, 2-year and 4-year observation time. We find that the full sensitivity curve is slightly lower for Taiji than for LISA at frequencies of $\leq 0.8$ mHz and around 2~mHz. For a 4-year lifetime, more than 29 thousand sources are resolvable with Taiji. Compared to LISA, Taiji can subtract $\sim 20 \%$ more sources and the distribution of them in our Milky Way is consistent with that of the resolvable sources with LISA.

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C. Liu, W. Ruan and Z. Guo
Tue, 10 Jan 23
83/93

Comments: 7 pages, 4 figures

A prototype tank for the SWGO detector [IMA]

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http://arxiv.org/abs/2301.02449


The Southern Wide-field Gamma-ray Observatory (SWGO) is an international collaboration working on realizing a next-generation observatory located in the Southern hemisphere, which offers a privileged view of our galactic center. We are working on the construction of a prototype water Cherenkov detector at Politecnico di Milano using a flexible testing facility for several candidate light sensors and configurations. A structure able to hold different types of detectors in multiple configurations has been designed, built and tested in Politecnico’s labs. Furthermore, an analytical study of muons and electrons showers has been carried out using the SWGO observatory simulation software to examine the correlation between the detection capabilities of the prototype tank and its water level.

Read this paper on arXiv…

S. Grusovin, G. Consolati, A. Angelis, et. al.
Mon, 9 Jan 23
21/59

Comments: N/A

Acoustic detection of UHE neutrinos: ANDIAMO perspectives [IMA]

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http://arxiv.org/abs/2301.02581


A possible detection of ultra-high-energy neutrinos has been attempted since decades through the Askarian radiation and different observation techniques. In fact, when such energetic neutrinos interact in a medium are able to produce a thermo-acoustic effect resulting in a bipolar pressure pulse that carries a portion of the energy generated by the particle cascades. This effect can be observed in atmosphere looking for the correlated radio emission and in ice/water searching directly the acoustic pulse. The kilometric attenuation length as well as the well-defined shape of the expected pulse favors a large-area-undersea-array of acoustic sensors as a possible observatory. Previous efforts of taking data with a undersea hydrophones array were obtained thanks to already installed submarine military arrays or acoustic system built to calibrate the positions of Cherenkov light detector units. In this proceeding we propose to use the based but not operative offshore oil rigs powered platforms in the Adriatic sea as the main infrastructure to build an acoustic submarine array of dedicated hydrophones covering a total surface area up to $\sim$10000 Km$^{2}$ and a volume up to $\sim$500 Km$^{3}$. A future identification of neutrino events at energies greater than 10$^{18}$ eV will confirm the presence of powerful accelerators in our Universe able to emit cosmic rays up to ZeV energy range.

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A. Marinelli, P. Migliozzi and A. Simonelli
Mon, 9 Jan 23
42/59

Comments: 9 pages, 3 figures. To appear in Proceedings of 27th European Cosmic Ray Symposium (Nijmegen July 2022)

Photochemical and RadiatiOn Transport model for Extensive USe (PROTEUS) [IMA]

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http://arxiv.org/abs/2301.02415


We introduce a new flexible one-dimensional photochemical model named Photochemical and RadiatiOn Transport model for Extensive USe (PROTEUS), which consists of a Python graphical user interface (GUI) program and Fortran 90 modules. PROTEUS is designed for adaptability to many planetary atmospheres, for flexibility to deal with thousands of or more chemical reactions with high efficiency, and for intuitive operation with GUI. Chemical reactions can be easily implemented into the Python GUI program in a simple string format, and users can intuitively select a planet and chemical reactions on GUI. Chemical reactions selected on GUI are automatically analyzed by string parsing functions in the Python GUI program, then applied to the Fortran 90 modules to simulate with the selected chemical reactions on a selected planet. PROTEUS can significantly save the time for those who need to develop a new photochemical model; users just need to write chemical reactions in the Python GUI program and just select them on GUI to run a new photochemical model.

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Y. Nakamura, N. Terada, S. Koyama, et. al.
Mon, 9 Jan 23
53/59

Comments: N/A

The Colorado Ultraviolet Transit Experiment (CUTE) Mission Overview [IMA]

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http://arxiv.org/abs/2301.02250


Atmospheric escape is a fundamental process that affects the structure, composition, and evolution of many planets. The signatures of escape are detectable on close-in, gaseous exoplanets orbiting bright stars, owing to the high levels of extreme-ultraviolet irradiation from their parent stars. The Colorado Ultraviolet Transit Experiment (CUTE) is a CubeSat mission designed to take advantage of the near-ultraviolet stellar brightness distribution to conduct a survey of the extended atmospheres of nearby close-in planets. The CUTE payload is a magnifying NUV (2479~–~3306 Ang) spectrograph fed by a rectangular Cassegrain telescope (206mm x 84mm); the spectrogram is recorded on a back-illuminated, UV-enhanced CCD. The science payload is integrated into a 6U Blue Canyon Technology XB1 bus. CUTE was launched into a polar, low-Earth orbit on 27 September 2021 and has been conducting this transit spectroscopy survey following an on-orbit commissioning period. This paper presents the mission motivation, development path, and demonstrates the potential for small satellites to conduct this type of science by presenting initial on-orbit science observations. The primary science mission is being conducted in 2022~–~2023, with a publicly available data archive coming on line in 2023.

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K. France, B. Fleming, A. Egan, et. al.
Mon, 9 Jan 23
55/59

Comments: 12 pages, 5 figures, AJ – accepted

The James Webb Space Telescope Mission: Optical Telescope Element Design, Development, and Performance [IMA]

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http://arxiv.org/abs/2301.01779


The James Webb Space Telescope (JWST) is a large, infrared space telescope that has recently started its science program which will enable breakthroughs in astrophysics and planetary science. Notably, JWST will provide the very first observations of the earliest luminous objects in the Universe and start a new era of exoplanet atmospheric characterization. This transformative science is enabled by a 6.6 m telescope that is passively cooled with a 5-layer sunshield. The primary mirror is comprised of 18 controllable, low areal density hexagonal segments, that were aligned and phased relative to each other in orbit using innovative image-based wavefront sensing and control algorithms. This revolutionary telescope took more than two decades to develop with a widely distributed team across engineering disciplines. We present an overview of the telescope requirements, architecture, development, superb on-orbit performance, and lessons learned. JWST successfully demonstrates a segmented aperture space telescope and establishes a path to building even larger space telescopes.

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M. McElwain, L. Feinberg, M. Perrin, et. al.
Fri, 6 Jan 23
6/55

Comments: accepted by PASP for JWST Overview Special Issue; 34 pages, 25 figures

On-sky performance of new 90 GHz detectors for the Cosmology Large Angular Scale Surveyor (CLASS) [IMA]

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http://arxiv.org/abs/2301.01417


The Cosmology Large Angular Scale Surveyor (CLASS) is a polarization-sensitive telescope array located at an altitude of 5,200 m in the Chilean Atacama Desert and designed to measure the polarized Cosmic Microwave Background (CMB) over large angular scales. The CLASS array is currently observing with three telescopes covering four frequency bands: one at 40 GHz (Q); one at 90 GHz (W1); and one dichroic system at 150/220 GHz (HF). During the austral winter of 2022, we upgraded the first 90 GHz telescope (W1) by replacing four of the seven focal plane modules. These new modules contain detector wafers with an updated design, aimed at improving the optical efficiency and detector stability. We present a description of the design changes and measurements of on-sky optical efficiencies derived from observations of Jupiter.

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C. Núñez, J. Appel, M. Brewer, et. al.
Thu, 5 Jan 23
16/51

Comments: 5 pages, 3 figures, submitted to the IEEE Transactions on Applied Superconductivity

Solar Sail Propulsion by 2050: An Enabling Capability for Heliophysics Missions [IMA]

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http://arxiv.org/abs/2301.01297


Solar sails enable missions to observe the solar environment from unique vantage points, such as sustained observations away from the Sun-Earth line; sub-L1 station keeping; high inclination solar orbits; Earth polar-sitting and polar-viewing observatories; fast transit missions to study heliosphere to interstellar medium transition, as well as missions of interest across a broad user community. Recent and planned demonstration missions make this technology ready for use on near-term science missions.

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L. Johnson, N. Barnes, M. Ceriotti, et. al.
Thu, 5 Jan 23
24/51

Comments: Heliophysics 2050 White Paper

ASCENT – A balloon-borne hard X-ray imaging spectroscopy telescope using transition edge sensor microcalorimeter detectors [IMA]

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http://arxiv.org/abs/2301.01525


Core collapse supernovae are thought to be one of the main sources in the galaxy of elements heavier than iron. Understanding the origin of the elements is thus tightly linked to our understanding of the explosion mechanism of supernovae and supernova nucleosynthesis. X-ray and gamma-ray observations of young supernova remnants, combined with improved theoretical modeling, have resulted in enormous improvements in our knowledge of these events. The isotope ${}^{44}$Ti is one of the most sensitive probes of the innermost regions of the core collapse engine, and its spatial and velocity distribution are key observables. Hard X-ray imaging spectroscopy with the Nuclear Spectroscopic Telescope Array (NuSTAR) has provided new insights into the structure of the supernova remnant Cassiopeia A (Cas A), establishing the convective nature of the supernova engine. However, many questions about the details of this engine remain. We present here the concept for a balloon-borne follow-up mission called ASCENT (A SuperConducting ENergetic x-ray Telescope). ASCENT uses transition edge sensor gamma-ray microcalorimeter detectors with a demonstrated 55 eV Full Width Half Maximum (FWHM) energy resolution at 97 keV. This 8–16-fold improvement in energy resolution over NuSTAR will allow high resolution imaging and spectroscopy of the ${}^{44}$Ti emission. This will allow a detailed reconstruction of gamma-ray line redshifts, widths, and shapes, allowing us to address questions such as: What is the source of the neutron star “kicks”? What is the dominant production pathway for ${}^{44}$Ti? Is the engine of Cas A unique?

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F. Kislat, D. Becker, D. Bennett, et. al.
Thu, 5 Jan 23
25/51

Comments: 23 pages, 11 figures

First on-sky results of ERIS at VLT [IMA]

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http://arxiv.org/abs/2301.01580


ERIS (Enhanced Resolution Imager and Spectrograph) is a new adaptive optics instrument installed at the Cassegrain focus of the VLT-UT4 telescope at the Paranal Observatory in Chile. ERIS consists of two near-infrared instruments: SPIFFIER, an integral field unit (IFU) spectrograph covering J to K bands, and NIX, an imager covering J to M bands. ERIS has an adaptive optics system able to work with both LGS and NGS. The Assembly Integration Verification (AIV) phase of ERIS at the Paranal Observatory was carried out starting in December 2021, followed by several commissioning runs in 2022. This contribution will describe the first preliminary results of the on-sky performance of ERIS during its commissioning and the future perspectives based on the preliminary scientific results.

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K. Kravchenko, Y. Dallilar, O. Absil, et. al.
Thu, 5 Jan 23
26/51

Comments: Proceeding of SPIE Astronomical Telescopes + Instrumentation 2022

The BlueWalker 3 Satellite Has Faded [IMA]

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http://arxiv.org/abs/2301.01601


Observations of BlueWalker 3 (BW3) beginning on December 8 of this year indicate that its apparent brightness had decreased. We postulate that the orbital beta angle and resultant solar power considerations required an adjustment to the satellite attitude around that time. So, the nominally zenith facing side of the flat-panel shaped spacecraft, which supports the solar array, was tilted toward the Sun. Consequently, the nadir side, which is seen by observers on the ground, was mostly dark. Thus, BW3 has generally appeared faint and on some occasions was not seen at all. The amount of fading was up to 4 magnitudes. Numerical modeling indicates that the amount of tilt was in the range 13{\deg} to 16{\deg}. This situation indicates the improvement in the appearance of BW3 from the ground that can be achieved with small tilts of the spacecraft. Satellite operators and astronomers can jointly address the adverse impact of bright satellites on celestial observations based on this finding.

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A. Mallama, R. Cole and S. Tilley
Thu, 5 Jan 23
30/51

Comments: N/A

The on-orbit performance of the Colorado Ultraviolet Transit Experiment (CUTE) Mission [IMA]

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http://arxiv.org/abs/2301.01307


We present the on-orbit performance of the Colorado Ultraviolet Transit Experiment ($CUTE$). $CUTE$ is a 6U CubeSat that launched on September 27th, 2021 and is obtaining near-ultraviolet (NUV, 2480 A — 3306 A) transit spectroscopy of short-period exoplanets. The instrument comprises a 20 cm $\times$ 8 cm rectangular Cassegrain telescope, an NUV spectrograph with a holographically ruled aberration-correcting diffraction grating, and a passively cooled, back-illuminated NUV-optimized CCD detector. The telescope feeds the spectrograph through an 18$’$ $\times$ 60$”$ slit. The spacecraft bus is a Blue Canyon Technologies XB1, which has demonstrated $\leq$ 6$”$ jitter in 56% of $CUTE$ science exposures. Following spacecraft commissioning, an on-orbit calibration program was executed to characterize the $CUTE$ instrument’s on-orbit performance. The results of this calibration indicate that the effective area of $CUTE$ is $\approx$ 19.0 — 27.5 cm$^{2}$ and that the average intrinsic resolution element is 2.9 A across the bandpass. This paper describes the measurement of the science instrument performance parameters as well as the thermal and pointing characteristics of the observatory.

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A. Egan, N. Nell, A. Suresh, et. al.
Thu, 5 Jan 23
46/51

Comments: N/A

An interference detection strategy for Apertif based on AOFlagger 3 [IMA]

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http://arxiv.org/abs/2301.01562


Context. Apertif is a multi-beam receiver system for the Westerbork Synthesis Radio Telescope that operates at 1.1-1.5 GHz, which overlaps with various radio services, resulting in contamination of astronomical signals with radio-frequency interference (RFI). Aims. We analyze approaches to mitigate Apertif interference and design an automated detection procedure for its imaging mode. Using this approach, we present long-term RFI detection results of over 300 Apertif observations. Methods. Our approach is based on the AOFlagger detection approach. We introduce several new features, including ways to deal with ranges of invalid data (e.g. caused by shadowing) in both the SumThreshold and scale-invariant rank operator steps; pre-calibration bandpass calibration; auto-correlation flagging; and HI flagging avoidance. These methods are implemented in a new framework that uses the Lua language for scripting, which is new in AOFlagger version 3. Results. Our approach removes RFI fully automatically, and is robust and effective enough for further calibration and (continuum) imaging of these data. Analysis of 304 observations show an average of 11.1% of lost data due to RFI with a large spread. We observe 14.6% RFI in auto-correlations. Computationally, AOFlagger achieves a throughput of 370 MB/s on a single computing node. Compared to published machine learning results, the method is one to two orders of magnitude faster.

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A. Offringa, B. Adebahr, A. Kutkin, et. al.
Thu, 5 Jan 23
48/51

Comments: 15 pages, 10 figures. Accepted for publication in A&A

Speckle Space-Time Covariance in High-Contrast Imaging [IMA]

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http://arxiv.org/abs/2301.01291


We introduce a new framework for point-spread function (PSF) subtraction based on the spatio-temporal variation of speckle noise in high-contrast imaging data where the sampling timescale is faster than the speckle evolution timescale. One way that space-time covariance arises in the pupil is as atmospheric layers translate across the telescope aperture and create small, time-varying perturbations in the phase of the incoming wavefront. The propagation of this field to the focal plane preserves some of that space-time covariance. To utilize this covariance, our new approach uses a Karhunen-Lo\’eve transform on an image sequence, as opposed to a set of single reference images as in previous applications of Karhunen-Lo\’eve Image Processing (KLIP) for high-contrast imaging. With the recent development of photon-counting detectors, such as microwave kinetic inductance detectors (MKIDs), this technique now has the potential to improve contrast when used as a post-processing step. Preliminary testing on simulated data shows this technique can improve contrast by at least 10-20% from the original image, with significant potential for further improvement. For certain choices of parameters, this algorithm may provide larger contrast gains than spatial-only KLIP.

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B. Lewis, M. Fitzgerald, R. Dodkins, et. al.
Wed, 4 Jan 23
7/43

Comments: Accepted to AJ

Science Platforms for Heliophysics Data Analysis [IMA]

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http://arxiv.org/abs/2301.00878


We recommend that NASA maintain and fund science platforms that enable interactive and scalable data analysis in order to maximize the scientific return of data collected from space-based instruments.

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M. Bobra, W. Barnes, T. Chen, et. al.
Wed, 4 Jan 23
17/43

Comments: Heliophysics 2050 White Paper

Search for Transient, Monochromatic Light from the Galactic Plane [IMA]

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http://arxiv.org/abs/2301.01230


The Galactic Plane was searched for transient, monochromatic light at optical and near-IR wavelengths to detect pulses shorter than 1 sec. An objective-prism Schmidt telescope and CMOS camera were used to observe 973 square degrees along the Galactic Plane within a strip 2.1 deg wide. The non-detections of laser pulses from the Galactic Plane add to the non-detections from more than 5000 stars. The absence of extraterrestrial beacons reveals more of a SETI desert at optical and radio wavelengths.

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G. Marcy and N. Tellis
Wed, 4 Jan 23
22/43

Comments: 24 pages

On second-order combinatorial algebraic time-delay interferometry [IMA]

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http://arxiv.org/abs/2301.00814


Inspired by the combinatorial algebraic approach proposed by Dhurandhar et al., we propose two novel classes of second-generation time-delay interferometry (TDI) solution as well as their further generalization. The primary strategy of the algorithm is to enumerate specific types of residual laser frequency noise associated with second-order commutators in products of time-displacement operators. The derivations are based on analyzing the delay time residual when expanded in time derivatives of the armlengths order by order. It is observed that the solutions obtained by such a scheme are primarily captured by the geometric TDI approach and therefore possess an intuitive interpretation. Nonetheless, the fully-symmetric Sagnac and Sagnac-inspired combinations inherit the properties from the original algebraic approach, and subsequently lie outside of the scope of geometric TDI. Moreover, at its lowest order, the solution is furnished by commutator of rather compact form. Besides the original Michelson-type solution, we elaborate on other types of solutions such as the Monitor, Beacon, Relay, Sagnac, fully-symmetric Sagnac, and Sagnac-inspired ones. The average response functions, residual noise power spectral density, and sensitivity curves are evaluated for the obtained solutions. Also, the relations between the present scheme and other existing algorithms are discussed.

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W. Qian, P. Wang, Z. Wu, et. al.
Wed, 4 Jan 23
25/43

Comments: 21 pages, 3 figures

Exploring the Solar Poles: The Last Great Frontier of the Sun [IMA]

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http://arxiv.org/abs/2301.00010


Despite investments in multiple space and ground-based solar observatories by the global community, the Sun’s polar regions remain unchartered territory – the last great frontier for solar observations. Breaching this frontier is fundamental to understanding the solar cycle – the ultimate driver of short-to-long term solar activity that encompasses space weather and space climate. Magnetohydrodynamic dynamo models and empirically observed relationships have established that the polar field is the primary determinant of the future solar cycle amplitude. Models of solar surface evolution of tilted active regions indicate that the mid to high latitude surges of magnetic flux govern dynamics leading to the reversal and build-up of polar fields. Our theoretical understanding and numerical models of this high latitude magnetic field dynamics and plasma flows – that are a critical component of the sunspot cycle – lack precise observational constraints. This limitation compromises our ability to observe the enigmatic kilo Gauss polar flux patches and constrain the polar field distribution at high latitudes. The lack of these observations handicap our understanding of how high latitude magnetic fields power polar jets, plumes, and the fast solar wind that extend to the boundaries of the heliosphere and modulate solar open flux and cosmic ray flux within the solar system. Accurate observation of the Sun’s polar regions, therefore, is the single most outstanding challenge that confronts Heliophysics. This paper argues the scientific case for novel out of ecliptic observations of the Sun’s polar regions, in conjunction with existing, or future multi-vantage point heliospheric observatories. Such a mission concept can revolutionize the field of Heliophysics like no other mission concept has – with relevance that transcends spatial regimes from the solar interior to the heliosphere.

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D. Nandy, D. Banerjee, P. Bhowmik, et. al.
Tue, 3 Jan 23
18/49

Comments: This White Paper was submitted in 2022 to the United States National Academies Solar and Space Physics (Heliophysics) Decadal Survey

Unification of thermal and quantum noise in gravitational-wave detectors [IMA]

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http://arxiv.org/abs/2301.00338


Contemporary gravitational-wave detectors are fundamentally limited by thermal noise — due to dissipation in the mechanical elements of the test mass — and quantum noise — from the vacuum fluctuations of the optical field used to probe the test mass position. Two other fundamental noises can in principle also limit sensitivity: test-mass quantization noise due to the zero-point fluctuation of its mechanical modes, and thermal excitation of the optical field. We use the quantum fluctuation-dissipation theorem to unify all four noises. This unified picture shows precisely when test-mass quantization noise and optical thermal noise can be ignored.

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C. Whittle, L. McCuller, V. Sudhir, et. al.
Tue, 3 Jan 23
22/49

Comments: 5 pages, 2 figures

PCA-based Data Reduction and Signal Separation Techniques for James-Webb Space Telescope Data Processing [IMA]

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http://arxiv.org/abs/2301.00415


Principal Component Analysis (PCA)-based techniques can separate data into different uncorrelated components and facilitate the statistical analysis as a pre-processing step. Independent Component Analysis (ICA) can separate statistically independent signal sources through a non-parametric and iterative algorithm. Non-negative matrix factorization is another PCA-similar approach to categorizing dimensions in physically-interpretable groups. Singular spectrum analysis (SSA) is a time-series-related PCA-like algorithm. After an introduction and a literature review on processing JWST data from the Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI), potential parts to intervene in the James Webb Space Telescope imaging data reduction pipeline will be discussed.

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G. Hatipoğlu
Tue, 3 Jan 23
24/49

Comments: 12 pages

A comparison of numerical methods for computing the reionization of intergalacitc hydrogen and helium by a central radiating source [IMA]

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http://arxiv.org/abs/2301.00450


We compare numerical methods for solving the radiative transfer equation in the context of the photoionization of intergalactic gaseous hydrogen and helium by a central radiating source. Direct integration of the radiative transfer equation and solutions using photon packets are examined, both for solutions to the time-dependent radiative transfer equation and in the infinite-speed-of-light approximation. The photon packet schemes are found to be more generally computationally efficient than a direct integration scheme. Whilst all codes accurately describe the growth rate of hydrogen and helium ionization zones, it is shown that a fully time-dependent method is required to capture the gas temperature and ionization structure in the near zone of a source when an ionization front expands at a speed close to the speed of light. Applied to Quasi-Stellar Objects in the Epoch of Reionization (EoR), temperature differences as high as $5\times10^4$ K result in the near-zone for solutions of the time-dependent radiative transfer equation compared with solutions in the infinite-speed-of-light approximation. Smaller temperature differences are found following the nearly full photoionization of helium in gas in which the hydrogen was already ionized and the helium was singly ionized. Variations found in the temperature and ionization structure far from the source, where the gas is predominantly neutral, may affect some predictions for 21-cm EoR experiments.

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K. Leong, A. Meiksin, A. Lai, et. al.
Tue, 3 Jan 23
37/49

Comments: 19 pages, 24 figures, submitted to MNRAS

End-to-end simulations of a near-infrared pyramid sensor on Keck II [IMA]

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http://arxiv.org/abs/2301.00590


The future upgrade of Keck II telescope’s adaptive optics system will include a pyramid wavefront sensor working in the near-infrared (J and H band). It will benefit from the recently developed avalanche photodiode arrays, specifically the SAPHIRA (Selex) array, which provides a low noise ($<$ 1 e- at high frame rates). The system will either work with a natural guide star (NGS) in a single conjugated adaptive optics system, or in a laser guide star (LGS) mode. In this case, the pyramid would be used as a low-order sensor only. We report on a study of the pyramid sensor’s performance via end-to-end simulations, applied to Keck’s specific case. We present the expected Strehl ratio with optimized configurations in NGS mode, and the expected residual on low orders in LGS mode. In the latter case, we also compare the pyramid to LIFT, a focal-plane sensor, demonstrating the ability of LIFT to provide a gain of about 2 magnitudes for low-order sensing.

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C. Plantet, G. Agapito, C. Giordano, et. al.
Tue, 3 Jan 23
46/49

Comments: N/A

A Bayesian Neural Network Approach to identify Stars and AGNs observed by XMM Newton [IMA]

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http://arxiv.org/abs/2301.00056


In today’s era, a tremendous amount of data is generated by different observatories and manual classification of data is something which is practically impossible. Hence, to classify and categorize the objects there are multiple machine and deep learning techniques used. However, these predictions are overconfident and won’t be able to identify if the data actually belongs to the trained class. To solve this major problem of overconfidence, in this study we propose a novel Bayesian Neural Network which randomly samples weights from a distribution as opposed to the fixed weight vector considered in the frequentist approach. The study involves the classification of Stars and AGNs observed by XMM Newton. However, for testing purposes, we consider CV, Pulsars, ULX, and LMX along with Stars and AGNs which the algorithm refuses to predict with higher accuracy as opposed to the frequentist approaches wherein these objects are predicted as either Stars or AGNs. The proposed algorithm is one of the first instances wherein the use of Bayesian Neural Networks is done in observational astronomy. Additionally, we also make our algorithm to identify stars and AGNs in the whole XMM-Newton DR11 catalogue. The algorithm almost identifies 62807 data points as AGNs and 88107 data points as Stars with enough confidence. In all other cases, the algorithm refuses to make predictions due to high uncertainty and hence reduces the error rate.

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S. Gharat and B. Bose
Tue, 3 Jan 23
48/49

Comments: 4 pages

D-Egg: a Dual PMT Optical Module for IceCube [IMA]

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http://arxiv.org/abs/2212.14526


The D-Egg, an acronym for “Dual optical sensors in an Ellipsoid Glass for Gen2,” is one of the optical modules designed for future extensions of the IceCube experiment at the South Pole. The D-Egg has an elongated-sphere shape to maximize the photon-sensitive effective area while maintaining a narrow diameter to reduce the cost and the time needed for drilling of the deployment holes in the glacial ice for the optical modules at depths up to 2700 meters. The D-Egg design is utilized for the IceCube Upgrade, the next stage of the IceCube project also known as IceCube-Gen2 Phase 1, where nearly half of the optical sensors to be deployed are D-Eggs. With two 8-inch high-quantum efficiency photomultiplier tubes (PMTs) per module, D-Eggs offer an increased effective area while retaining the successful design of the IceCube digital optical module (DOM). The convolution of the wavelength-dependent effective area and the Cherenkov emission spectrum provides an effective photodetection sensitivity that is 2.8 times larger than that of IceCube DOMs. The signal of each of the two PMTs is digitized using ultra-low-power 14-bit analog-to-digital converters with a sampling frequency of 240 MSPS, enabling a flexible event triggering, as well as seamless and lossless event recording of single-photon signals to multi-photons exceeding 200 photoelectrons within 10 nanoseconds. Mass production of D-Eggs has been completed, with 277 out of the 310 D-Eggs produced to be used in the IceCube Upgrade. In this paper, we report the des\ ign of the D-Eggs, as well as the sensitivity and the single to multi-photon detection performance of mass-produced D-Eggs measured in a laboratory using the built-in data acquisition system in each D-Egg optical sensor module.

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R. Abbasi, M. Ackermann, J. Adams, et. al.
Mon, 2 Jan 23
11/44

Comments: 26 pages, 18 figures, 1 table

Data-driven photometric redshift estimation from type Ia supernovae light curves [IMA]

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http://arxiv.org/abs/2212.14668


Redshift measurement has always been a constant need in modern astronomy and cosmology. And as new surveys have been providing an immense amount of data on astronomical objects, the need to process such data automatically proves to be increasingly necessary. In this article, we use simulated data from the Dark Energy Survey, and from a pipeline originally created to classify supernovae, we developed a linear regression algorithm optimized through novel automated machine learning (AutoML) frameworks achieving an error score better than ordinary data pre-processing methods when compared with other modern algorithms (such as XGBOOST). Numerically, the photometric prediction RMSE of type Ia supernovae events was reduced from 0.16 to 0.09 and the RMSE of all supernovae types decreased from 0.20 to 0.14. Our pipeline consists of four steps: through spectroscopic data points we interpolate the light curve using Gaussian process fitting algorithm, then using a wavelet transform we extract the most important features of such curves; in sequence we reduce the dimensionality of such features through principal component analysis, and in the end we applied super learning techniques (stacked ensemble methods) through an AutoML framework dedicated to optimize the parameters of several different machine learning models, better resolving the problem. As a final check, we obtained probability distribution functions (PDFs) using Gaussian kernel density estimations through the predictions of more than 50 models trained and optimized by AutoML. Those PDFs were calculated to replicate the original curves that used SALT2 model, a model used for the simulation of the raw data itself.

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F. Oliveira, M. Santos and R. Reis
Mon, 2 Jan 23
12/44

Comments: N/A

Towards data-driven modeling and real-time prediction of solar flares and coronal mass ejections [IMA]

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http://arxiv.org/abs/2212.14384


Modeling of transient events in the solar atmosphere requires the confluence of 3 critical elements: (1) model sophistication, (2) data availability, and (3) data assimilation. This white paper describes required advances that will enable statistical flare and CME forecasting (e.g. eruption probability and timing, estimation of strength, and CME details, such as speed and magnetic field orientation) similar to weather prediction on Earth.

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M. Rempel, Y. Fan, M. Dikpati, et. al.
Mon, 2 Jan 23
14/44

Comments: Heliophysics 2050 White Paper

Data Reduction Process and Pipeline for the NIC Polarimetry Mode in Python, NICpolpy [IMA]

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http://arxiv.org/abs/2212.14167


A systematic way of data reduction for the Nishiharima Infrared Camera (NIC) polarimetry mode has been devised and implemented to an open software called NICpolpy in the programming language python (tested on version 3.8–3.10 as of writing). On top of the classical methods, including vertical pattern removal, a new way of diagonal pattern (Fourier pattern) removal has been implemented. Each image undergoes four reduction steps, resulting in “level 1” to “level 4” products, as well as nightly calibration frames. A simple tutorial and in-depth descriptions are provided, as well as the descriptions of algorithms. The dome flat frames (taken on UT 2020-06-03) were analyzed, and the pixel positions vulnerable to flat error were found. Using the dark and flat frames, the detector parameters, gain factor (the conversion factor), and readout noise are also updated. We found gain factor and readout noise are likely constants over pixel or “quadrant”.

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Y. Bach, M. Ishiguro, J. Takahashi, et. al.
Mon, 2 Jan 23
24/44

Comments: For the PyPI of the package NICpolpy, see this https URL ; For the development at GitHub, see this https URL; this http URL

Web-based telluric correction made in Spain: spectral fitting of Vega-type telluric standards [IMA]

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http://arxiv.org/abs/2212.14068


Infrared spectroscopic observations from the ground must be corrected from telluric contamination to make them ready for scientific analyses. However, telluric correction is often a tedious process that requires significant expertise to yield accurate results in a reasonable time frame. To solve these inconveniences, we present a new method for telluric correction that employs a roughly simultaneous observation of a Vega analog to measure atmospheric transmission. After continuum reconstruction and spectral fitting, the stellar features are removed from the observed Vega-type spectrum and the result is used for cancelling telluric absorption features on science spectra. This method is implemented as TelCorAl (Telluric Correction from Alicante), a Python-based web application with a user-friendly interface, whose beta version will be released soon.

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D. Fuente, A. Marco, L. Patrick, et. al.
Mon, 2 Jan 23
38/44

Comments: 6 pages, 2 figures. To be published in Highlights of Spanish Astrophysics XI, Proceedings of the XV Scientific Meeting of the Spanish Astronomical Society

Population of ground and lowest excited states of Sulfur via the dissociative recombination of SH+ in the diffuse interstellar medium [IMA]

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http://arxiv.org/abs/2212.13538


Our previous study on dissociative recombination of ground state SH$^+$ into $^2\Pi$ states of SH is extended by taking into account the contribution of $^4\Pi$ states recently explored by quantum chemistry methods. Multichannel quantum defect theory is employed for the computation of cross sections and rate coefficients for dissociative recombination, but also for vibrational excitation. Furthermore, we produce the atomic yields resulting from recombination, quantifying the generation of sulfur atoms in their ground (\mbox{$^3$P}) and lowest excited (\mbox{$^1$D}) states respectively.

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J. Boffelli, F. Gauchet, D. Kashinski, et. al.
Thu, 29 Dec 22
4/47

Comments: 9 pages, 8 figures, 3 tables

Deep Learning for Space Weather Prediction: Bridging the Gap between Heliophysics Data and Theory [IMA]

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http://arxiv.org/abs/2212.13328


Traditionally, data analysis and theory have been viewed as separate disciplines, each feeding into fundamentally different types of models. Modern deep learning technology is beginning to unify these two disciplines and will produce a new class of predictively powerful space weather models that combine the physical insights gained by data and theory. We call on NASA to invest in the research and infrastructure necessary for the heliophysics’ community to take advantage of these advances.

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J. Dorelli, C. Bard, T. Chen, et. al.
Thu, 29 Dec 22
8/47

Comments: Heliophysics 2050 White Paper

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.

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M. Miyoshi
Thu, 29 Dec 22
11/47

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

ISAI: Investigating Solar Axion by Iron-57 [IMA]

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http://arxiv.org/abs/2212.13708


The existence of the axion is a unique solution for the strong CP problem, and the axion is one of the most promising candidates of the dark matter. Investigating Solar Axion by Iron-57 (ISAI) is being prepared as a complemented table-top experiment to confirm the solar axion scenario. Probing an X-ray emission from the nuclear transitions associated with the axion-nucleon coupling is a leading approach. ISAI searches for the monochromatic 14.4 keV X-ray from the first excited state of 57Fe using a state-of-the-art pixelized silicon detector, dubbed XRPIX, under an extremely low-background environment. We highlight scientific objectives, experimental design and the latest status of ISAI.

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T. Ikeda, T. Fujii, T. Tsuru, et. al.
Thu, 29 Dec 22
19/47

Comments: N/A

Heliophysics Discovery Tools for the 21st Century: Data Science and Machine Learning Structures and Recommendations for 2020-2050 [IMA]

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http://arxiv.org/abs/2212.13325


Three main points: 1. Data Science (DS) will be increasingly important to heliophysics; 2. Methods of heliophysics science discovery will continually evolve, requiring the use of learning technologies [e.g., machine learning (ML)] that are applied rigorously and that are capable of supporting discovery; and 3. To grow with the pace of data, technology, and workforce changes, heliophysics requires a new approach to the representation of knowledge.

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R. McGranaghan, B. Thompson, E. Camporeale, et. al.
Thu, 29 Dec 22
35/47

Comments: 4 pages; Heliophysics 2050 White Paper

Artificial Intelligence to Enhance Mission Science Output for In-situ Observations: Dealing with the Sparse Data Challenge [IMA]

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http://arxiv.org/abs/2212.13289


In the Earth’s magnetosphere, there are fewer than a dozen dedicated probes beyond low-Earth orbit making in-situ observations at any given time. As a result, we poorly understand its global structure and evolution, the mechanisms of its main activity processes, magnetic storms, and substorms. New Artificial Intelligence (AI) methods, including machine learning, data mining, and data assimilation, as well as new AI-enabled missions will need to be developed to meet this Sparse Data challenge.

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M. Sitnov, G. Stephens, V. Merkin, et. al.
Thu, 29 Dec 22
36/47

Comments: 4 pages, 1 figure; Heliophysics 2050 White Paper

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.

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M. Yamatani, Y. Nakagami, H. Fuke, et. al.
Thu, 29 Dec 22
37/47

Comments: 7 pages, 10 figures

Adaptive Optics system of the Evanescent Wave Coronagraph (EvWaCo): optimised phase plate and DM characterisation [IMA]

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http://arxiv.org/abs/2212.13818


The Evanescent Wave Coronagraph (EvWaCo) is an achromatic coronagraph mask with adjustable size over the spectral domain [600nm, 900nm] that will be installed at the Thai National Observatory. We present in this work the development of a bench to characterise its Extreme Adaptive Optics system (XAO) comprising a DM192 ALPAO deformable mirror (DM) and a 15×15 Shack-Hartmann wavefront sensor (SH-WFS). In this bench, the turbulence is simulated using a rotating phase plate in a pupil plane. In general, such components are designed using a randomly generated phase screen. Such single realisation does not necessarily provide the wanted structure function. We present a solution to design the printed pattern to ensure that the beam sees a strict and controlled Kolmogorov statistics with the correct 2D structure function. This is essential to control the experimental conditions in order to compare the bench results with the numerical simulations and predictions. This bench is further used to deeply characterise the full 27 mm pupil of the ALPAO DM using a 54×54 ALPAO SH-WFS. We measure the average shape of its influence functions as well as the influence function of each single actuator to study their dispersion. We study the linearity of the actuator amplitude with the command as well as the linearity of the influence function profile. We also study the actuator offsets as well as the membrane shape at 0-command. This knowledge is critical to get a forward model of the DM for the XAO control loop.

Read this paper on arXiv…

A. Berdeu, S. Sukpholtham, P. Kongkaew, et. al.
Thu, 29 Dec 22
45/47

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