AutoSourceID-FeatureExtractor. Optical images analysis using a Two-Step MVE Network for feature estimation and uncertainty characterization [IMA]

http://arxiv.org/abs/2305.14495


Aims. In astronomy, machine learning has demonstrated success in various tasks such as source localization, classification, anomaly detection, and segmentation. However, feature regression remains an area with room for improvement. We aim to design a network that can accurately estimate sources’ features and their uncertainties from single-band image cutouts, given the approximated locations of the sources provided by the previously developed code ASID-L or other external catalogues. Methods. The algorithm presented here, AutoSourceID-FeatureExtractor (ASID-FE), uses single-band cutouts of 32×32 pixels around the localized sources to estimate flux, sub-pixel centre coordinates, and their uncertainties. ASID-FE employs what we call a TS-MVE, a Two-Step Mean Variance Estimator approach to first estimate the features and then their uncertainties without the need for additional information, e.g. Point Spread Function (PSF). Results. We show that ASID-FE, trained on synthetic images from the MeerLICHT telescope, can predict more accurate features with respect to similar codes like SourceExtractor and that the two-step method can estimate well-calibrated uncertainties that are better behaved compared to similar methods that use deep ensembles of simple MVE networks. Finally, we evaluate the model on real images from the MeerLICHT telescope and the Zwicky Transients Facility (ZTF) to test its Transfer Learning abilities.

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F. Stoppa, R. Austri, P. Vreeswijk, et. al.
Thu, 25 May 23
64/64

Comments: N/A

Flux Calibration of CHIME/FRB Intensity Data [IMA]

http://arxiv.org/abs/2305.11302


Fast radio bursts (FRBs) are bright radio transients of micro-to-millisecond duration and unknown extragalactic origin. Central to the mystery of FRBs are their extremely high characteristic energies, which surpass the typical energies of other radio transients of similar duration, like Galactic pulsar and magnetar bursts, by orders of magnitude. Calibration of FRB-detecting telescopes for burst flux and fluence determination is crucial for FRB science, as these measurements enable studies of the FRB energy and brightness distribution in comparison to progenitor theories. The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is a radio interferometer of cylindrical design. This design leads to a high FRB detection rate but also leads to challenges for CHIME/FRB flux calibration. This paper presents a comprehensive review of these challenges, as well as the automated flux calibration software pipeline that was developed to calibrate bursts detected in the first CHIME/FRB catalog, consisting of 536 events detected between July 25th, 2018 and July 1st, 2019. We emphasize that, due to limitations in the localization of CHIME/FRB bursts, flux and fluence measurements produced by this pipeline are best interpreted as lower limits, with uncertainties on the limiting value.

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B. Andersen, C. Patel, C. Brar, et. al.
Mon, 22 May 23
6/60

Comments: 29 pages, 13 figures, submitted to AJ

Computational Methods for Collisional Stellar Systems [IMA]

http://arxiv.org/abs/2305.11606


Dense star clusters are spectacular self-gravitating stellar systems in our Galaxy and across the Universe – in many respects. They populate disks and spheroids of galaxies as well as almost every galactic center. In massive elliptical galaxies nuclear clusters harbor supermassive black holes, which might influence the evolution of their host galaxies as a whole. The evolution of dense star clusters is not only governed by the aging of their stellar populations and simple Newtonian dynamics. For increasing particle number, unique gravitational effects of collisional many-body systems begin to dominate the early cluster evolution. As a result, stellar densities become so high that stars can interact and collide, stellar evolution and binary stars change the dynamical evolution, black holes can accumulate in their centers and merge with relativistic effects becoming important. Recent high-resolution imaging has revealed even more complex structural properties with respect to stellar populations, binary fractions and compact objects as well as – the still controversial – existence of intermediate mass black holes in clusters of intermediate mass. Dense star clusters therefore are the ideal laboratory for the concomitant study of stellar evolution and Newtonian as well as relativistic dynamics. Not only the formation and disruption of dense star clusters has to be considered but also their galactic environments in terms of initial conditions as well as their impact on galactic evolution. This review deals with the specific computational challenges for modelling dense, gravothermal star clusters.

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R. Spurzem and A. Kamlah
Mon, 22 May 23
39/60

Comments: 98 pages, 13 figures, invited article for Living Reviews in Computational Astrophysics

A new technique to measure noise parameters for global 21-cm experiments [IMA]

http://arxiv.org/abs/2305.11479


Radiometer experiments to detect 21-cm Hydrogen line emission from the Cosmic Dawn and Epoch of Reionization rely upon precise absolute calibration. During calibration, noise generated by amplifiers within the radiometer receiver must be accounted for; however, it is difficult to measure as the noise power varies with source impedance. In this letter, we introduce a convenient method to measure the noise parameters of a receiver system, which is practical for low-frequency receivers used in global 21-cm experiments.

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D. Price, C. Tong, A. Sutinjo, et. al.
Mon, 22 May 23
45/60

Comments: 4 pages, accepted paper for URSI GASS 2023 J08

A GPU-accelerated viewer for HEALPix maps [IMA]

http://arxiv.org/abs/2305.11507


HEALPix by G\’orski et. al. (2005) is de-facto standard for Cosmic Microwave Background (CMB) data storage and analysis, and is widely used in current and upcoming CMB experiments. Almost all the datasets in Legacy Archive for Microwave Background Data Analysis (LAMBDA) use HEALPix as a format of choice. Visualizing the data plays important role in research, and several toolsets were developed to do that with HEALPix maps, most notably original Fortran facilities and Python integration with healpy.
With the current state of GPU performance, it is now possible to visualize extremely large maps in real time on a laptop or a tablet. HEALPix Viewer described here is developed for macOS, and takes full advantage of GPU acceleration to handle extremely large datasets in real time. It compiles natively on Intel and Arm64 architectures, and uses Metal framework for high-performance GPU computations. The aim of this project is to reduce the effort required for interactive data exploration, as well as time overhead for producing publication-quality maps. Drag and drop integration with Keynote and Powerpoint makes creating presentations easy.
The main codebase is written in Swift, a modern and efficient compiled language, with high-performance computing parts delegated entirely to GPU, and a few inserts in C interfacing to cfitsio library for I/O. Graphical user interface is written in SwiftUI, a new declarative UI framework based on Swift. Most common spherical projections and colormaps are supported out of the box, and the available source code makes it easy to customize the application and to add new features if desired.

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A. Frolov
Mon, 22 May 23
52/60

Comments: 10 pages; 7 figures

MiraBest: A Dataset of Morphologically Classified Radio Galaxies for Machine Learning [IMA]

http://arxiv.org/abs/2305.11108


The volume of data from current and future observatories has motivated the increased development and application of automated machine learning methodologies for astronomy. However, less attention has been given to the production of standardised datasets for assessing the performance of different machine learning algorithms within astronomy and astrophysics. Here we describe in detail the MiraBest dataset, a publicly available batched dataset of 1256 radio-loud AGN from NVSS and FIRST, filtered to $0.03 < z < 0.1$, manually labelled by Miraghaei and Best (2017) according to the Fanaroff-Riley morphological classification, created for machine learning applications and compatible for use with standard deep learning libraries. We outline the principles underlying the construction of the dataset, the sample selection and pre-processing methodology, dataset structure and composition, as well as a comparison of MiraBest to other datasets used in the literature. Existing applications that utilise the MiraBest dataset are reviewed, and an extended dataset of 2100 sources is created by cross-matching MiraBest with other catalogues of radio-loud AGN that have been used more widely in the literature for machine learning applications.

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F. Porter and A. Scaife
Fri, 19 May 23
7/46

Comments: 14 pages, 2 figures, accepted by RASTI

Satellite Optical Brightness [IMA]

http://arxiv.org/abs/2305.11123


The apparent brightness of satellites is calculated as a function of satellite position as seen by a ground-based observer in darkness. Both direct illumination of the satellite by the sun as well as indirect illumination due to reflection from the Earth are included. The reflecting properties of each satellite component and of the Earth must first be estimated (the Bidirectional Reflectance Distribution Function, BRDF). Integrating over all scattering surfaces leads to the angular pattern of the flux reflected from the satellite. Finally, the apparent brightness of the satellite as seen by an observer at a given location is calculated as a function of satellite position. We validate our calculations by comparing to observations of selected Starlink satellites and show significant improvement on previous satellite brightness models. With multiple observations of a satellite at various solar angles and with minimal assumptions regarding the satellite, BRDF model coefficients for each satellite component can be accurately inferred, obviating the need to import direct BRDF lab measurements. This widens the effectiveness of this model approach to virtually all satellites. This work finds application in satellite design and operations, and in planning observatory data acquisition and analysis. Similar methodology for predicting satellite brightness has already informed mitigation strategies for next generation Starlink satellites.

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F. Fankhauser, J. Tyson and J. Askari
Fri, 19 May 23
17/46

Comments: 14 pages, 12 figures

Optical Alignment Method for the PRIME Telescope [IMA]

http://arxiv.org/abs/2305.10796


We describe the optical alignment method for the Prime-focus Infrared Microlensing Experiment (PRIME) telescope which is a prime-focus near-infrared (NIR) telescope with a wide field of view for the microlensing planet survey toward the Galactic center that is the major task for the PRIME project. There are three steps for the optical alignment: preliminary alignment by a laser tracker, fine alignment by intra- and extra-focal (IFEF) image analysis technique, and complementary and fine alignment by the Hartmann test. We demonstrated that the first two steps work well by the test conducted in the laboratory in Japan. The telescope was installed at the Sutherland Observatory of South African Astronomical Observatory in August, 2022. At the final stage of the installation, we demonstrated that the third method works well and the optical system satisfies the operational requirement.

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H. Yama, D. Suzuki, S. Miyazaki, et. al.
Fri, 19 May 23
32/46

Comments: 16 pages, 10 figures, and 6 tables. Accept for publication in Journal of Astronomical Instrumentation

A Simple Code for Rotational Broadening of Broad Wavelength Range High-Dispersion Spectra [IMA]

http://arxiv.org/abs/2305.09693


In high dispersion spectra of rotating bodies such as stars and planets, the rotation contributes significantly to, and sometimes dominates, the line broadening. We present a simple method for rotationally broadening large wavelength ranges of high-dispersion spectra. The broadening is rapid and scales linearly with the length of the spectrum array. For large wavelength ranges, the method is much faster than the popular convolution-based broadening. We provide the code implementation of this method in a publicly accessible repository.

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A. Carvalho and C. Johns-Krull
Thu, 18 May 23
3/67

Comments: 2 pages, 1 figure, published in RNAAS

Coded Mask Instruments for Gamma-Ray Astronomy [IMA]

http://arxiv.org/abs/2305.10130


Coded mask instruments have been used in high-energy astronomy for the last forty years now and designs for future hard X-ray/low gamma-ray telescopes are still based on this technique when they need to reach moderate angular resolutions over large field of views, particularly for observations dedicated to the, now flourishing, field of time domain astrophysics. However these systems are somehow unfamiliar to the general astronomers as they actually are two-step imaging devices where the recorded picture is very different from the imaged object and the data processing takes a crucial part in the reconstruction of the sky image. Here we present the concepts of these optical systems applied to high-energy astronomy, the basic reconstruction methods including some useful formulae and the trend of the expected and observed performances as function of the system designs. We review the historical developments and recall the flown space-borne coded mask instruments along with the description of a few relevant examples of major successful implementations and future projects in space astronomy.

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A. Goldwurm and A. Gros
Thu, 18 May 23
6/67

Comments: Review (55 pages, 26 figures) published in Handbook of X-ray and Gamma-ray Astrophysics, edited by Cosimo Bambi and Andrea Santangelo, Springer Living Reference Work, ISBN: 978-981-16-4544-0, 2022, id.15

Advanced Data Analysis for Observational Cosmology: applications to the study of the Intergalactic Medium [IMA]

http://arxiv.org/abs/2305.10182


The analysis of absorption features along the line of sight to distant sources is an invaluable tool for observational cosmology, giving a direct insight into the physical and chemical state of the inter/circumgalactic medium. Such endeavour entails the accessibility of bright QSOs as background beacons, and the availability of software tools to extract the information in a reproducible way. In this article, we will present the latest results we obtained in both directions within the QUBRICS project: we will describe how machine learning techniques were applied to detect hundreds of previously unknown QSOs in the southern hemisphere, and how state-of-the art software like QSFit and Astrocook was integrated in the analysis of the targets, opening up new possibilities for the next era of observations.

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G. Cupani, G. Calderone, S. Cristiani, et. al.
Thu, 18 May 23
8/67

Comments: 4 pages, 2 figures; proceedings of ADASS XXXI, accepted by ASP Conference Series

Performance of the Quasar Spectral Templates for the Dark Energy Spectroscopic Instrument [IMA]

http://arxiv.org/abs/2305.10426


Millions of quasar spectra will be collected by the Dark Energy Spectroscopic Instrument (DESI), leading to a four-fold increase in the number of known quasars. High accuracy quasar classification is essential to tighten constraints on cosmological parameters measured at the highest redshifts DESI observes ($z>2.0$). We present the spectral templates for identification and redshift estimation of quasars in the DESI Year 1 data release. The quasar templates are comprised of two quasar eigenspectra sets, trained on spectra from the Sloan Digital Sky Survey. The sets are specialized to reconstruct quasar spectral variation observed over separate yet overlapping redshift ranges and, together, are capable of identifying DESI quasars from $0.05 < z <7.0$. The new quasar templates show significant improvement over the previous DESI quasar templates regarding catastrophic failure rates, redshift precision and accuracy, quasar completeness, and the contamination fraction in the final quasar sample.

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A. Brodzeller, K. Dawson, S. Bailey, et. al.
Thu, 18 May 23
9/67

Comments: submitted to Astronomical Journal; 20 pages, 6 figures

Mitigating the Non-Linearities in a Pyramid Wavefront Sensor [IMA]

http://arxiv.org/abs/2305.09805


For natural guide start adaptive optics (AO) systems, pyramid wavefront sensors (PWFSs) can provide significant increase in sensitivity over the traditional Shack-Hartmann, but at the cost of a reduced linear range. When using a linear reconstructor, non-linearities result in wavefront estimation errors, which can have a significant impact on the image quality delivered by the AO system. Here we simulate a wavefront passing through a PWFS under varying observing conditions to explore the possibility of using a non-linear machine learning model to estimate wavefront errors better than a linear reconstruction. We find significant improvement even with light-weight models, underscoring the need for further investigation of this approach.

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F. Archinuk, R. Hafeez, S. Fabbro, et. al.
Thu, 18 May 23
14/67

Comments: N/A

Deep Learning Applications Based on WISE Infrared Data: Classification of Stars, Galaxies and Quasars [IMA]

http://arxiv.org/abs/2305.10217


The Wide-field Infrared Survey Explorer (WISE) has detected hundreds of millions of sources over the entire sky. However, classifying them reliably is a great challenge due to degeneracies in WISE multicolor space and low detection levels in its two longest-wavelength bandpasses. In this paper, the deep learning classification network, IICnet (Infrared Image Classification network), is designed to classify sources from WISE images to achieve a more accurate classification goal. IICnet shows good ability on the feature extraction of the WISE sources. Experiments demonstrates that the classification results of IICnet are superior to some other methods; it has obtained 96.2% accuracy for galaxies, 97.9% accuracy for quasars, and 96.4% accuracy for stars, and the Area Under Curve (AUC) of the IICnet classifier can reach more than 99%. In addition, the superiority of IICnet in processing infrared images has been demonstrated in the comparisons with VGG16, GoogleNet, ResNet34, MobileNet, EfficientNetV2, and RepVGG-fewer parameters and faster inference. The above proves that IICnet is an effective method to classify infrared sources.

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G. Zhao, B. Qiu, A. Luo, et. al.
Thu, 18 May 23
18/67

Comments: N/A

The Radio Detector of the Pierre Auger Observatory — status and expected performance [IMA]

http://arxiv.org/abs/2305.10104


As part of the ongoing AugerPrime upgrade of the Pierre Auger Observatory, we are deploying short aperiodic loaded loop antennas measuring radio signals from extensive air showers in the 30-80 MHz band on each of the 1,660 surface detector stations. This new Radio Detector of the Observatory allows us to measure the energy in the electromagnetic cascade of inclined air showers with zenith angles larger than $\sim 65^\circ$. The water-Cherenkov detectors, in turn, perform a virtually pure measurement of the muon component of inclined air showers. The combination of both thus extends the mass-composition sensitivity of the upgraded Observatory to high zenith angles and therefore enlarges the sky coverage of mass-sensitive measurements at the highest energies while at the same time allowing us to cross-check the performance of the established detectors with an additional measurement technique. In this contribution, we outline the concept and design of the Radio Detector, report on its current status and initial results from the first deployed stations, and illustrate its expected performance with a detailed, end-to-end simulation study.

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Tim Huege
Thu, 18 May 23
32/67

Comments: Contribution to the proceedings of the UHECR2022 conference, L’Aquila, Italy

End-to-end simulation and analysis pipeline for LISA [IMA]

http://arxiv.org/abs/2305.09702


The data produced by the future space-based millihertz gravitational-wave detector LISA will require nontrivial pre-processing, which might affect the science results. It is crucial to demonstrate the feasibility of such processing algorithms and assess their performance and impact on the science. We are building an end-to-end pipeline that includes state-of-the-art simulations and noise reduction algorithms. The simulations must include a detailed model of the full measurement chain, capturing the main features that affect the instrument performance and processing algorithms. In particular, we include in these simulations, for the first time, proper relativistic treatment of reference frames with realistic numerically-optimized orbits; a model for onboard clocks and clock synchronization measurements; proper modeling of total laser frequencies, including laser locking, frequency planning and Doppler shifts; and a better treatment of onboard processing. Using these simulated data, we show that our pipeline is able to reduce the most critical noises and form synchronized observables. By injecting signals from a verification binary, we demonstrate that good parameter estimation can be obtained on this more realistic setup, extending existing results from previous LISA Data Challenges.

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B. Jean-Baptiste, H. Olaf, L. Marc, et. al.
Thu, 18 May 23
35/67

Comments: Moriond Gravitation 2023 Proceedings, 7 pages, 5 figures

Air-Shower Radio Simulations — Where we stand and where we go [IMA]

http://arxiv.org/abs/2305.10100


Simulations of the radio emission from extensive air showers have been key in establishing radio detection as a mature and competitive technique. In particular, microscopic Monte Carlo simulations have proven to very accurately describe the emission physics and are at the heart of practically all analysis approaches. Yet with new applications — for example very inclined air showers, cross-media showers, extreme antenna densities, and higher-frequency measurements — come new challenges for accurate and efficient simulations. I will review the state of the art of the existing simulation approaches and discuss where further improvements might be needed and how they can be achieved.

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T. Huege
Thu, 18 May 23
52/67

Comments: Contribution to the proceedings of the ARENA2022 conference, Santiago de Compostela, Spain

Euclid preparation. XXIX. Water ice in spacecraft part I: The physics of ice formation and contamination [IMA]

http://arxiv.org/abs/2305.10107


Molecular contamination is a well-known problem in space flight. Water is the most common contaminant and alters numerous properties of a cryogenic optical system. Too much ice means that Euclid’s calibration requirements and science goals cannot be met. Euclid must then be thermally decontaminated, a long and risky process. We need to understand how iced optics affect the data and when a decontamination is required. This is essential to build adequate calibration and survey plans, yet a comprehensive analysis in the context of an astrophysical space survey has not been done before.
In this paper we look at other spacecraft with well-documented outgassing records, and we review the formation of thin ice films. A mix of amorphous and crystalline ices is expected for Euclid. Their surface topography depends on the competing energetic needs of the substrate-water and the water-water interfaces, and is hard to predict with current theories. We illustrate that with scanning-tunnelling and atomic-force microscope images.
Industrial tools exist to estimate contamination, and we must understand their uncertainties. We find considerable knowledge errors on the diffusion and sublimation coefficients, limiting the accuracy of these tools. We developed a water transport model to compute contamination rates in Euclid, and find general agreement with industry estimates. Tests of the Euclid flight hardware in space simulators did not pick up contamination signals; our in-flight calibrations observations will be much more sensitive.
We must understand the link between the amount of ice on the optics and its effect on Euclid’s data. Little research is available about this link, possibly because other spacecraft can decontaminate easily, quenching the need for a deeper understanding. In our second paper we quantify the various effects of iced optics on spectrophotometric data.

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E. Collaboration, M. Schirmer, K. Thürmer, et. al.
Thu, 18 May 23
67/67

Comments: 35 pages, 22 figures, accepted for publication in A&A

A Conditional Denoising Diffusion Probabilistic Model for Radio Interferometric Image Reconstruction [IMA]

http://arxiv.org/abs/2305.09121


In radio astronomy, signals from radio telescopes are transformed into images of observed celestial objects, or sources. However, these images, called dirty images, contain real sources as well as artifacts due to signal sparsity and other factors. Therefore, radio interferometric image reconstruction is performed on dirty images, aiming to produce clean images in which artifacts are reduced and real sources are recovered. So far, existing methods have limited success on recovering faint sources, preserving detailed structures, and eliminating artifacts. In this paper, we present VIC-DDPM, a Visibility and Image Conditioned Denoising Diffusion Probabilistic Model. Our main idea is to use both the original visibility data in the spectral domain and dirty images in the spatial domain to guide the image generation process with DDPM. This way, we can leverage DDPM to generate fine details and eliminate noise, while utilizing visibility data to separate signals from noise and retaining spatial information in dirty images. We have conducted experiments in comparison with both traditional methods and recent deep learning based approaches. Our results show that our method significantly improves the resulting images by reducing artifacts, preserving fine details, and recovering dim sources. This advancement further facilitates radio astronomical data analysis tasks on celestial phenomena.

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R. Wang, Z. Chen, Q. Luo, et. al.
Wed, 17 May 23
5/67

Comments: 8 pages

The First Results of Distributed Peer Review at ESO Show Promising Outcomes [IMA]

http://arxiv.org/abs/2305.09277


The European Southern Observatory (ESO) implemented a new paradigm called Distributed Peer Review (DPR) as part of its proposal evaluation process in Period 110. Under DPR, Principal Investigators who submit proposals agree to review a certain number of proposals submitted by their peers and accept that their own proposal(s) are reviewed by their peers who have also submitted proposals in the same cycle. This article presents a brief overview of the DPR process at ESO, and its outcomes based on data from periods 110 and 111.

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T. Jerabkova, F. Patat, F. Primas, et. al.
Wed, 17 May 23
25/67

Comments: Published in the ESO Messenger

First Impressions: Early-Time Classification of Supernovae using Host Galaxy Information and Shallow Learning [IMA]

http://arxiv.org/abs/2305.08894


Substantial effort has been devoted to the characterization of transient phenomena from photometric information. Automated approaches to this problem have taken advantage of complete phase-coverage of an event, limiting their use for triggering rapid follow-up of ongoing phenomena. In this work, we introduce a neural network with a single recurrent layer designed explicitly for early photometric classification of supernovae. Our algorithm leverages transfer learning to account for model misspecification, host galaxy photometry to solve the data scarcity problem soon after discovery, and a custom weighted loss to prioritize accurate early classification. We first train our algorithm using state-of-the-art transient and host galaxy simulations, then adapt its weights and validate it on the spectroscopically-confirmed SNe~Ia, SNe~II, and SNe~Ib/c from the Zwicky Transient Facility Bright Transient Survey. On observed data, our method achieves an overall accuracy of $82 \pm 2$% within 3 days of an event’s discovery, and an accuracy of $87 \pm 5$% within 30 days of discovery. At both early and late phases, our method achieves comparable or superior results to the leading classification algorithms with a simpler network architecture. These results help pave the way for rapid photometric and spectroscopic follow-up of scientifically-valuable transients discovered in massive synoptic surveys.

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A. Gagliano, G. Contardo, D. Mackey, et. al.
Wed, 17 May 23
43/67

Comments: 24 pages, 8 figures. Resubmitted to ApJ. Comments welcome

The Next Generation Arecibo Telescope: A preliminary study [IMA]

http://arxiv.org/abs/2305.07780


The Next Generation Arecibo Telescope (NGAT) was a concept presented in a white paper Roshi et al. (2021) developed by members of the Arecibo staff and user community immediately after the collapse of the 305 m legacy telescope. A phased array of small parabolic antennas placed on a tiltable plate-like structure forms the basis of the NGAT concept. The phased array would function both as a transmitter and as a receiver. This envisioned state of the art instrument would offer capabilities for three research fields, viz. radio astronomy, planetary and space & atmospheric sciences. The proposed structure could be a single plate or a set of closely spaced segments, and in either case it would have an equivalent collecting area of a parabolic dish of size 300 m. In this study we investigate the feasibility of realizing the structure. Our analysis shows that, although a single structure ~300 m in size is achievable, a scientifically competitive instrument 130 to 175 m in size can be developed in a more cost effective manner. We then present an antenna configuration consisting of one hundred and two 13 m diameter dishes. The diameter of an equivalent collecting area single dish would be ~130 m, and the size of the structure would be ~146 m. The weight of the structure is estimated to be 4300 tons which would be 53% of the weight of the Green Bank Telescope. We refer to this configuration as NGAT-130. We present the performance of the NGAT-130 and show that it surpasses all other radar and single dish facilities. Finally, we briefly discuss its competitiveness for radio astronomy, planetary and space & atmospheric science applications.

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D. Roshi, S. Marshall, A. Vishwas, et. al.
Tue, 16 May 23
7/83

Comments: 6 pages, 5 figures, 1 table, Invited paper for the ICEAA-IEEE APWC conference, Venice, Italy, Oct 9-13, 2023

EASpy: Fast simulation of fluorescence and Cherenkov light from extended air showers at large zenith angles [IMA]

http://arxiv.org/abs/2305.08710


The detailed simulation of extended air showers (EAS) and their emission of Cherenkov and fluorescence light requires increasing computation time and storage volume with increasing energy of the primary particle. Given these limitations, it is currently challenging to optimize configurations of imaging air Cherenkov telescopes at photon energies beyond approximately 100 TeV. Additionally, the existing simulation frameworks are not capable of capturing the interplay of Cherenkov and fluorescence light emission at large zenith angle distances ($\gtrsim 70^\circ$), where the collection area of Cherenkov telescopes considerably increases. Here, we present EASpy, a framework for the simulation of EAS at large zenith angles using parametrizations for electron-positron distributions. Our proposed approach for the emission of fluorescence and Cherenkov light and the subsequent imaging of these components by Imaging Atmospheric Cherenkov Telescopes (IACTs) aims to provide flexibility and accuracy while at the same time it reduces the computation time considerably compared to full Monte Carlo simulations. We find excellent agreement of the resulting Cherenkov images when comparing results obtained from EASpy with the de-facto standard simulation tool CORSIKA and sim_telarray. In the process of verifying our approach, we have found that air shower images appear wider and longer with increasing impact distance at large zenith angles, an effect that has previously not been noted. We also investigate the distribution of light on the ground for fluorescence and Cherenkov emission and highlight their key differences to distributions at moderate zenith angles.

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A. Baktash and D. Horns
Tue, 16 May 23
12/83

Comments: N/A

Effects of the Hunga Tonga-Hunga Ha'apai Volcanic Eruption on Observations at Paranal Observatory [IMA]

http://arxiv.org/abs/2305.08620


The Hunga Tonga-Hunga Ha’apai volcano erupted on 15 January 2022 with an energy equivalent to around 61 megatons of TNT. The explosion was bigger than any other volcanic eruption so far in the 21st century. Huge quantities of particles, including dust and water vapour, were released into the atmosphere. We present the results of a preliminary study of the effects of the explosion on observations taken at Paranal Observatory using a range of instruments. These effects were not immediately transitory in nature, and a year later stunning sunsets are still being seen at Paranal.

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R. Rosa, A. Otarola, T. Szeifert, et. al.
Tue, 16 May 23
29/83

Comments: 4 pages, 5 figures, published in ESO Messenger vol. 190

Application of Graph Networks to background rejection in Imaging Air Cherenkov Telescopes [IMA]

http://arxiv.org/abs/2305.08674


Imaging Air Cherenkov Telescopes (IACTs) are essential to ground-based observations of gamma rays in the GeV to TeV regime. One particular challenge of ground-based gamma-ray astronomy is an effective rejection of the hadronic background. We propose a new deep-learning-based algorithm for classifying images measured using single or multiple Imaging Air Cherenkov Telescopes. We interpret the detected images as a collection of triggered sensors that can be represented by graphs and analyzed by graph convolutional networks. For images cleaned of the light from the night sky, this allows for an efficient algorithm design that bypasses the challenge of sparse images in deep learning approaches based on computer vision techniques such as convolutional neural networks. We investigate different graph network architectures and find a promising performance with improvements to previous machine-learning and deep-learning-based methods.

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J. Glombitza, V. Joshi, B. Bruno, et. al.
Tue, 16 May 23
48/83

Comments: N/A

In-orbit background simulation of a type-B CATCH satellite [IMA]

http://arxiv.org/abs/2305.08589


The Chasing All Transients Constellation Hunters (CATCH) space mission plans to launch three types of micro-satellites (A, B, and C). The type-B CATCH satellites are dedicated to locating transients and detecting their time-dependent energy spectra. A type-B satellite is equipped with lightweight Wolter-I X-ray optics and an array of position-sensitive multi-pixel Silicon Drift Detectors. To optimize the scientific payloads for operating properly in orbit and performing the observations with high sensitivities, this work performs an in-orbit background simulation of a type-B CATCH satellite using the Geant4 toolkit. It shows that the persistent background is dominated by the cosmic X-ray diffuse background and the cosmic-ray protons. The dynamic background is also estimated considering trapped charged particles in the radiation belts and low-energy charged particles near the geomagnetic equator, which is dominated by the incident electrons outside the aperture. The simulated persistent background within the focal spot is used to estimate the observation sensitivity, i.e. 4.22$\times$10$^{-13}$ erg cm$^{-2}$ s$^{-1}$ with an exposure of 10$^{4}$ s and a Crab-like source spectrum, which can be utilized further to optimize the shielding design. The simulated in-orbit background also suggests that the magnetic diverter just underneath the optics may be unnecessary in this kind of micro-satellites, because the dynamic background induced by charged particles outside the aperture is around 3 orders of magnitude larger than that inside the aperture.

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J. Xiao, L. Qi, S. Zhang, et. al.
Tue, 16 May 23
56/83

Comments: 24 pages, 13 figures, 7 tables, accepted for publication in Experimental Astronomy

Observing exoplanets from Antarctica in two colours: Set-up and operation of ASTEP+ [IMA]

http://arxiv.org/abs/2305.08454


On December 2021, a new camera box for two-colour simultaneous visible photometry was successfully installed on the ASTEP telescope at the Concordia station in Antarctica. The new focal box offers increased capabilities for the ASTEP+ project. The opto-mechanical design of the camera was described in a previous paper. Here, we focus on the laboratory tests of each of the two cameras, the low-temperature behaviour of the focal box in a thermal chamber, the on-site installation and alignment of the new focal box on the telescope, the measurement of the turbulence in the tube and the operation of the telescope equipped with the new focal box. We also describe the data acquisition and the telescope guiding procedure and provide a first assessment of the performances reached during the first part of the 2022 observation campaign. Observations of the WASP19 field, already observed previously with ASTEP, demonstrates an improvement of the SNR by a factor 1.7, coherent with an increased number of photon by a factor of 3. The throughput of the two cameras is assessed both by calculation of the characteristics of the optics and quantum efficiency of the cameras, and by direct observations on the sky. We find that the ASTEP+ two-colour transmission curves (with a dichroic separating the fluxes at 690nm) are similar to those of GAIA in the blue and red channels, but with a lower transmission in the ASTEP+ red channel leading to a 1.5 magnitude higher B-R value compared to the GAIA B-R value. With this new setting, the ASTEP+ telescope will ensure the follow-up and the characterization of a large number of exoplanetary transits in the coming years in view of the future space missions JWST and Ariel.

Read this paper on arXiv…

F. Schmider, L. Abe, A. Agabi, et. al.
Tue, 16 May 23
72/83

Comments: 12 pages, 12 figures. Proceedings of Ground-based and Airborne Telescopes IX SPIE conference 2022

Ground-based monitoring of the variability of visible Solar spectral lines for improved understanding of solar and stellar magnetism and dynamics [IMA]

http://arxiv.org/abs/2305.07676


Long-term high-cadence measurements of stellar spectral variability are fundamental to better understand stellar atmospheric properties and stellar magnetism. These, in turn, are fundamental for the detectability of exoplanets as well as the characterization of their atmospheres and habitability. The Sun, viewed as a star via disk-integrated observations, offers a means of exploring such measurements while also offering the spatially resolved observations that are necessary to discern the causes of observed spectral variations. High-spectral resolution observations of the solar spectrum are fundamental for a variety of Earth-system studies, including climate influences, renewable energies, and biology. The Integrated Sunlight Spectrometer at SOLIS, has been acquiring daily high-spectral resolution Sun-as-a-star measurements since 2006.More recently, a few ground-based telescopes with the capability of monitoring the solar visible spectrum at high spectral resolution have been deployed (e.g. PEPSI, HARPS, NEID). However, the main scientific goal of these instruments is to detect exo-planets, and solar observations are acquired mainly as a reference. Consequently, their technical requirements are not ideal to monitor solar variations with high photometric stability, especially over solar-cycle temporal scales.The goal of this white paper is to emphasize the scientific return and explore the technical requirements of a network of ground-based spectrographs devoted to long-term monitoring of disk-integrated solar-spectral variability with high spectral resolution and high photometric stability, in conjunction with disk-resolved observations in selected spectral lines,to complement planet-hunter measurements and stellar-variability studies. The proposed network of instruments offers the opportunity for a larger variety of multidisciplinary studies.

Read this paper on arXiv…

S. Criscuoli, L. Bertello, D. Choudhary, et. al.
Tue, 16 May 23
73/83

Comments: Submitted to the Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033

Forecasting the power of Higher Order Weak Lensing Statistics with automatically differentiable simulations [IMA]

http://arxiv.org/abs/2305.07531


We present the Differentiable Lensing Lightcone (DLL), a fully differentiable physical model designed for being used as a forward model in Bayesian inference algorithms requiring access to derivatives of lensing observables with respect to cosmological parameters. We extend the public FlowPM N-body code, a particle-mesh N-body solver, simulating lensing lightcones and implementing the Born approximation in the Tensorflow framework. Furthermore, DLL is aimed at achieving high accuracy with low computational costs. As such, it integrates a novel Hybrid Physical-Neural parameterisation able to compensate for the small-scale approximations resulting from particle-mesh schemes for cosmological N-body simulations. We validate our simulations in an LSST setting against high-resolution $\kappa$TNG simulations by comparing both the lensing angular power spectrum and multiscale peak counts. We demonstrate an ability to recover lensing $C_\ell$ up to a 10% accuracy at $\ell=1000$ for sources at redshift 1, with as few as $\sim 0.6$ particles per Mpc/h. As a first use case, we use this tool to investigate the relative constraining power of the angular power spectrum and peak counts statistic in an LSST setting. Such comparisons are typically very costly as they require a large number of simulations, and do not scale well with the increasing number of cosmological parameters. As opposed to forecasts based on finite differences, these statistics can be analytically differentiated with respect to cosmology, or any systematics included in the simulations at the same computational cost of the forward simulation. We find that the peak counts outperform the power spectrum on the cold dark matter parameter $\Omega_c$, on the amplitude of density fluctuations $\sigma_8$, and on the amplitude of the intrinsic alignment signal $A_{IA}$.

Read this paper on arXiv…

D. Lanzieri, F. Lanusse, C. Modi, et. al.
Mon, 15 May 23
37/53

Comments: Submitted to A&A, 18 pages, 14 figures, comments are welcome

The nuclear reaction network WinNet [IMA]

http://arxiv.org/abs/2305.07048


We present the state-of-the-art single-zone nuclear reaction network WinNet that is capable of calculating the nucleosynthetic yields of a large variety of astrophysical environments and conditions. This ranges from the calculation of the primordial nucleosynthesis where only a few nuclei are considered to the ejecta of neutron star mergers with several thousands of involved nuclei. Here we describe the underlying physics and implementation details of the reaction network. We additionally present the numerical implementation of two different integration methods, the implicit Euler method and Gears method along with their advantages and disadvantages. We furthermore describe basic example cases of thermodynamic conditions that we provide together with the network and demonstrate the reliability of the code by using simple test cases. Once the manuscript has been accepted for publication, WinNet will be publicly available and open source.

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M. Reichert, C. Winteler, O. Korobkin, et. al.
Mon, 15 May 23
44/53

Comments: N/A

On-Site Production of Quasi-Continuous Ultra-High Vacuum Pipes [IMA]

http://arxiv.org/abs/2305.06698


We present a design study for a new production technology for ultra-high vacuum pipes. The pipes are produced in a fully automatised process in sections of hundreds of meters directly in the later location of usage. We estimate the effort for such a production and show that it might be substantially lower than the effort for an off-site production of transportable sections.

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M. Angerhausen, G. Buchholz, J. Hoste, et. al.
Fri, 12 May 23
40/53

Comments: 12 pages, 4 figures

Improved ranking statistics of the GstLAL inspiral search for compact binary coalescences [IMA]

http://arxiv.org/abs/2305.06286


Starting from May 2023, the LIGO Scientific, Virgo and KAGRA Collaboration is planning to conduct the fourth observing run with improved detector sensitivities and an expanded detector network including KAGRA. Accordingly, it is vital to optimize the detection algorithm of low-latency search pipelines, increasing their sensitivities to gravitational waves from compact binary coalescences. In this work, we discuss several new features developed for ranking statistics of GstLAL-based inspiral pipeline, which mainly consist of: the signal contamination removal, the bank-$\xi^2$ incorporation, the upgraded $\rho-\xi^2$ signal model and the integration of KAGRA. An injection study demonstrates that these new features improve the pipeline’s sensitivity by approximately 15% to 20%, paving the way to further multi-messenger observations during the upcoming observing run.

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L. Tsukada, P. Joshi, S. Adhicary, et. al.
Thu, 11 May 23
42/55

Comments: 13pages, 6figures

Laboratory demonstration of the wrapped staircase scalar vortex coronagraph [IMA]

http://arxiv.org/abs/2305.05076


Of the over 5000 exoplanets that have been detected, only about a dozen have ever been directly imaged. Earth-like exoplanets are on the order of 10 billion times fainter than their host star in visible and near-infrared, requiring a coronagraph instrument to block primary starlight and allow for the imaging of nearby orbiting planets. In the pursuit of direct imaging of exoplanets, scalar vortex coronagraphs (SVCs) are an attractive alternative to vector vortex coronagraphs (VVCs). VVCs have demonstrated 2e-9 raw contrast in broadband light but have several limitations due to their polarization properties. SVCs imprint the same phase ramp as VVCs on the incoming light and do not require polarization splitting, but they are inherently chromatic. Discretized phase ramp patterns such as a wrapped staircase help reduce SVC chromaticity and simulations show it outperforms a chromatic classical vortex in broadband light. We designed, fabricated, and tested a wrapped staircase SVC, and here we present the broadband characterization on the high contrast spectroscopy testbed. We also performed wavefront correction on the in-air coronagraph testbed at NASA’s Jet Propulsion Laboratory and achieved an average raw contrasts of 3.2e-8 in monochromatic light and 2.2e-7 across a 10% bandwidth.

Read this paper on arXiv…

N. Desai, G. Ruane, J. Llop-Sayson, et. al.
Wed, 10 May 23
1/65

Comments: arXiv admin note: text overlap with arXiv:2212.02633

Atomic Layer Deposited Protective Coating of Aluminum Oxide on Silver-based Telescope Mirror A Comparison Between a Pure Ozone and H2O Precursor [IMA]

http://arxiv.org/abs/2305.05109


Although silver-based telescope mirrors excel over other materials such as gold and aluminum in the visible-infrared spectral range, they require robust protective coatings to overcome their inherent low durability. Our research shows that a single-layer of aluminum oxide (AlOx) deposited through thermal atomic layer deposition (ALD) using trimethylaluminum (TMA) and water (H2O) at low temperatures (~60{\deg}C) serves as an acceptable protective coating without adversely impacting the optical performance of the mirrors. While silver-based mirrors protected with a single-layer of AlOx perform decently in the field, in environmental tests under high-humidity at high-temperature conditions that accelerate underlying failure mechanisms, they degrade quickly, suggesting that there is room for improvement. This paper describes a study that compares the performance and endurance of two sets of silver-based mirrors protected by a single-layer of AlOx prepared by thermal ALD with two types of oxygen precursors: H2O and pure ozone (PO). The study shows that while the two types of samples, regardless of their oxygen precursors, initially have comparable spectral reflectance, the reflectance of the samples with AlOx protective coatings prepared with PO remain nearly constant 1.6 times longer than those with AlOx protective coatings prepared with H2O in the environmental test, suggesting promising characteristics of AlOx protective coatings prepared with PO.

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S. Tornøe, B. Cheney, B. Dupraw, et. al.
Wed, 10 May 23
12/65

Comments: 18 pages, 5 figures, 1 table

RAM: Rapid Advection Algorithm on Arbitrary Meshes [IMA]

http://arxiv.org/abs/2305.05362


The study of many astrophysical flows requires computational algorithms that can capture high Mach number flows, while resolving a large dynamic range in spatial and density scales. In this paper we present a novel method, RAM: Rapid Advection Algorithm on Arbitrary Meshes. RAM is a time-explicit method to solve the advection equation in problems with large bulk velocity on arbitrary computational grids. In comparison with standard up-wind algorithms, RAM enables advection with larger time steps and lower truncation errors. Our method is based on the operator splitting technique and conservative interpolation. Depending on the bulk velocity and resolution, RAM can decrease the numerical cost of hydrodynamics by more than one order of magnitude. To quantify the truncation errors and speed-up with RAM, we perform one and two-dimensional hydrodynamics tests. We find that the order of our method is given by the order of the conservative interpolation and that the effective speed up is in agreement with the relative increment in time step. RAM will be especially useful for numerical studies of disk-satellite interaction, characterized by high bulk orbital velocities, and non-trivial geometries. Our method dramatically lowers the computational cost of simulations that simultaneously resolve the global disk and well inside the Hill radius of the secondary companion.

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P. Benítez-Llambay, L. Krapp, X. Ramos, et. al.
Wed, 10 May 23
14/65

Comments: 15 pages, 7 figures. Submitted to ApJ. Comments are welcome

Initial On-Sky Performance testing of the Single-Photon Imager for Nanosecond Astrophysics (SPINA) system [IMA]

http://arxiv.org/abs/2305.05197


This work presents an initial on-sky performance measurement of the Single-Photon Imager for Nanosecond Astrophysics (SPINA) system, part of our Ultra-Fast Astronomy (UFA) program. We developed the SPINA system based on the position-sensitive silicon photomultiplier (PS-SiPM) detector to record both photoelectron (P.E.) temporal and spatial information. The initial on-sky testing of the SPINA system was successfully performed on UT 2022 Jul 10, on the 0.7-meter aperture Nazarbayev University Transient Telescope at the Assy-Turgen Astrophysical Observatory (NUTTelA-TAO). We measured stars with a wide range of brightness and a dark region of the sky without stars $< 18$ mag. We measured the SPINA system’s spatial resolution to be $<232\mu m$ (full-width half-maximum, FWHM), limited by the unstable atmosphere. We measured the total background noise (detector dark counts and sky background) of 1914 counts per second (cps) within this resolution element. We also performed a crosstalk mapping of the detector, obtaining the crosstalk probability of $\sim0.18$ near the detector’s center while reaching $\sim 50\%$ at the edges. We derived a $5\sigma$ sensitivity of $17.45$ Gaia-BP magnitude in a 1s exposure with no atmospheric extinction by comparing the received flux with Gaia-BP band data. For a $10ms$ window and a false alarm rate of once per 100 nights, we derived a transient sensitivity of 14.06 mag. For a $1\mu s$ or faster time scale, we are limited by crosstalk to a 15 P.E. detection threshold. In addition, we demonstrated that the SPINA system is capable of capturing changes in the stellar profile FWHM of $\pm1.8\%$ and $\pm5\%$ change in the stellar profile FWHM in $20ms$ and $2ms$ exposures, respectively, as well as capturing stellar light curves on the $ms$ and $\mu s$ scales.

Read this paper on arXiv…

A. Lau, N. Shaimoldin, Z. Maksut, et. al.
Wed, 10 May 23
36/65

Comments: N/A

Bayesian radio interferometric imaging with direction-dependent calibration [IMA]

http://arxiv.org/abs/2305.05489


Context: Radio interferometers measure frequency components of the sky brightness, modulated by the gains of the individual radio antennas. Due to atmospheric turbulence and variations in the operational conditions of the antennas these gains fluctuate. Thereby the gains do not only depend on time but also on the spatial direction on the sky. To recover high quality radio maps an accurate reconstruction of the direction and time-dependent individual antenna gains is required. Aims: This paper aims to improve the reconstruction of radio images, by introducing a novel joint imaging and calibration algorithm including direction-dependent antenna gains. Methods: Building on the \texttt{resolve} framework, we designed a Bayesian imaging and calibration algorithm utilizing the image domain gridding method for numerically efficient application of direction-dependent antenna gains. Furthermore by approximating the posterior probability distribution with variational inference, our algorithm can provide reliable uncertainty maps. Results: We demonstrate the ability of the algorithm to recover high resolution high dynamic range radio maps from VLA data of the radio galaxy Cygnus A. We compare the quality of the recovered images with previous work relying on classically calibrated data. Furthermore we compare with a compressed sensing algorithm also incorporating direction-dependent gains. Conclusions: Including direction-dependent effects in the calibration model significantly improves the dynamic range of the reconstructed images compared to reconstructions from classically calibrated data. Compared to the compressed sensing reconstruction, the resulting sky images have a higher resolution and show fewer artifacts. For utilizing the full potential of radio interferometric data, it is essential to consider the direction dependence of the antenna gains.

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J. Roth, P. Arras, M. Reinecke, et. al.
Wed, 10 May 23
46/65

Comments: 13 pages, 9 figures

Pulsar Observations at low latitudes and low frequencies [IMA]

http://arxiv.org/abs/2305.05458


The Pulsar Monitoring in Argentina (PuMA) is a collaboration between the Argentine Institute for Radioastronomy (IAR) and the Rochester Institute of Technology (RIT) that since 2017 has been observing southern sky pulsars with high cadence using the two restored IAR antennas in the L-Band (1400MHz). We briefly review the first set of results of this program to study transient phenomena, such as magnetars and glitching pulsars, as well as to perform precise timing of millisecond pulsars. Access to lower frequency bands, where most of the pulsars are brighter, would allow us to reach additional pulsars, currently buried into the background noise. We identify two dozen additional glitching pulsars that could be observable in the 400MHz band by the IAR’s projected Multipurpose Interferometer Array (MIA). We also discuss the relevance and challenges of single-pulse pulsar timing at low frequencies and the search for Fast Radio Burst (FRB) in the collected data since 2017 using machine learning techniques.

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C. Lousto, R. Missel, E. Zubieta, et. al.
Wed, 10 May 23
58/65

Comments: 11 pages, 10 figures, 5 tables. arXiv admin note: text overlap with arXiv:2108.13462

Research on access, use and effective exploration of astronomical observational and bibliographical data from sonification [IMA]

http://arxiv.org/abs/2305.05635


Data analysis in space sciences has been performed exclusively visually for years, despite the fact that the largest amount of data belongs to non-visible portions of the electromagnetic spectrum. This, on the one hand, limits the study of the unknown to the current resolution possibilities of the screens, and on the other hand, it excludes a group of people who present some type of visual disability. Taking into account the aforementioned, and that people with some type of disability encounter many barriers to achieve academic studies and stable jobs, the present investigation focuses on new modalities of access to the data, but taking into account the accessibility and inclusion of people with functional diversity from the beginning. It has been shown that multimodal perception (use of more than one sense) can be a good complement to visual exploration and understanding of complex scientific data. This is especially true for astrophysical data, composed of a sum of different oscillatory modes resulting in the final complex data array. This proposal focuses on the human ability to adapt to data and interaction with sound, in order to analyze data sets and produce an application aimed at leveling the possibilities of access to information in the field of physics and astronomy (although the tool is also applicable to any type of data in files with 2 or more columns (.txt or .csv)) for people with disabilities. In addition, it proposes the study of scientific and technological capacities for the generation of tools with a novel approach, focused on the user and oriented to: a specific social problem, the use of free programming languages and the design of infrastructure to improve inclusion.

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J. Casado and B. García
Wed, 10 May 23
61/65

Comments: Thesis of 265 pages with bibliography, in Spanish language, the rest are appends

Theoretical Study on the Potential Existing Forms and Microwave Rotational Spectrum of Short-Chain Fatty Acids in Interstellar Space [IMA]

http://arxiv.org/abs/2305.04762


Several short-chain fatty acids and their corresponding potential existing hydrated forms are important molecules in interstellar space. Their structures were optimized with twelve different computational methods. The dipole moments and the spectral constants, including rotational constants and centrifugal distortion constants were obtained. According to the benchmark study, revDSD-PBEP86-D3(BJ) is the most suitable method that was selected for rotational calculation. Symmetry-adapted perturbation theory was used to study the strength and composition of the interaction between acids and water in clusters. The possibility of its existing under the low-temperature and low-pressure conditions was confirmed by calculating of binding free energy. Furthermore, ab initio molecular dynamics simulations were used to investigate whether the internal rotations of acids could be observed. The 3-fold splitting from the predicted high-resolution microwave rotational spectra of the acetic acid monohydrate at different temperatures perfectly proved the accuracy of the simulations.

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F. Mu, H. Wang, Z. He, et. al.
Tue, 9 May 23
30/88

Comments: N/A

Studying X-ray instruments with galaxy clusters [IMA]

http://arxiv.org/abs/2305.04785


We applied a scientific approach to the problem of the effective area cross-calibration of the XMM-Newton EPIC instruments. Using a sample of galaxy clusters observed with the XMM-Newton EPIC, we quantified the effective area cross-calibration bias between the EPIC instruments as implemented in the public calibration data base on November 2021 in the 0.5-6.1 keV energy band. We invested significant efforts in controlling and minimising the systematic uncertainties of the cross-calibration bias below 1%. The statistical uncertainties are similar and thus we can reliably measure effects at 1% level. The effective area cross-calibration in the 0.5-6.1 keV band between MOS and pn is biased at a substantial level. The MOS/pn bias is systematic suggesting that MOS (pn) effective area may be calibrated too low (high), by $\sim$3-27% on average depending on the instrument and energy band. The excellent agreement of the energy dependencies (i.e. shapes) of the effective area of MOS2 and pn suggest that they are correctly calibrated within $\sim$1% in the 0.5-4.5 keV band. Comparison with an independent data set of point sources (3XMM) confirms this. The cluster sample indicates that the MOS1/pn effective area shape cross-calibration has an approximately linear bias amounting to $\sim$10% in maximum in the 0.5-4.5 keV band. The effective area cross-calibration of XMM-Newton/EPIC instruments on November 2021 in the 0.5-4.5 keV band is in a relatively good shape. However, the cluster-to-cluster rms scatter of the bias is substantial compared to the median bias itself. Thus, a statistically robust implementation of the cross-calibration uncertainties to a scientific analysis of XMM-Newton/EPIC data should include the propagation of the scatter to the best-fit parameters, instead of a simple average bias correction of the effective area.

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J. Nevalainen and S. Molendi
Tue, 9 May 23
31/88

Comments: Accepted for publication in Astronomy and Astrophysics. The tools implementing the results of this work are publicly available at this https URL

uGMRT Band 4 Polarimetry [IMA]

http://arxiv.org/abs/2305.04420


This is a technical report for band 4 (550-900 MHz) polarization data with the upgraded GMRT (uGMRT). The report describes the band 4 polarization data analysis procedure and includes notes for observers who are planning polarization observations with the uGMRT. A few pipelines that are currently being used and tested by astronomers at NCRA are discussed as well.

Read this paper on arXiv…

P. Kharb, S. Sasikumar, J. Baghel, et. al.
Tue, 9 May 23
35/88

Comments: 16 pages, 9 figures, NCRA Technical Report

Toward robust detections of nanohertz gravitational waves [IMA]

http://arxiv.org/abs/2305.04464


The recent observation of a common red-noise process in pulsar timing arrays (PTAs) suggests that the detection of nanohertz gravitational waves might be around the corner. However, in order to confidently attribute this red process to gravitational waves, one must observe the Hellings-Downs curve — the telltale angular correlation function associated with a gravitational-wave background. This effort is complicated by the complex modelling of pulsar noise. Without proper care, mis-specified noise models can lead to false-positive detections. Background estimation using bootstrap methods such as sky scrambles and phase shifts, which use the data to characterize the noise, are therefore important tools for assessing significance. We investigate the ability of current PTA experiments to estimate their background with “quasi-independent” scrambles — characterized by a statistical “match” below the fiducial value: $|M|<0.1$. We show that sky scrambling is affected by “saturation” after ${\cal O}(10)$ quasi-independent realizations; subsequent scrambles are no longer quasi-independent. We show phase scrambling saturates after ${\cal O}(100)$ quasi-independent realizations. With so few independent scrambles, it is difficult to make reliable statements about the $\gtrsim 5 \sigma$ tail of the null distribution of the detection statistic. We discuss various methods by which one may increase the number of independent scrambles. We also consider an alternative approach wherein one re-frames the background estimation problem so that the significance is calculated using statistically \textit{dependent} scrambles. The resulting $p$-value is in principle well-defined but may be susceptible to failure if assumptions about the data are incorrect.

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V. Marco, A. Zic, M. Miles, et. al.
Tue, 9 May 23
59/88

Comments: N/A

A fast method of reionization parameter space exploration using GPR trained SCRIPT [IMA]

http://arxiv.org/abs/2305.04839


Efficient exploration of parameter spaces is crucial to extract physical information about the Epoch of Reionization from various observational probes. To this end, we propose a fast technique based on Gaussian Process Regression (GPR) training applied to a semi-numerical photon-conserving reionization model, SCRIPT. Our approach takes advantage of the numerical convergence properties of SCRIPT and constructs a training set based on low-cost, coarse-resolution simulations. A likelihood emulator is then trained using this set to produce results in approximately two orders of magnitude less computational time than a full MCMC run, while still generating reasonable 68% and 95% confidence contours. Furthermore, we conduct a forecasting study using simulated data to demonstrate the applicability of this technique. This method is particularly useful when full MCMC analysis is not feasible due to expensive likelihood computations.

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B. Maity, A. Paranjape and T. Choudhury
Tue, 9 May 23
68/88

Comments: Submitted to MNRAS

Bright-Moon Sky as a Wide-Field Linear Polarimetric Flat Source for Calibration [IMA]

http://arxiv.org/abs/2305.04270


Next-generation wide-field optical polarimeters like the Wide-Area Linear Optical Polarimeters (WALOPs) have a field of view (FoV) of tens of arcminutes. For efficient and accurate calibration of these instruments, wide-field polarimetric flat sources will be essential. Currently, no established wide-field polarimetric standard or flat sources exist. This paper tests the feasibility of using the polarized sky patches of the size of around ten-by-ten arcminutes, at a distance of up to 20 degrees from the Moon, on bright-Moon nights as a wide-field linear polarimetric flat source. We observed 19 patches of the sky adjacent to the bright-Moon with the RoboPol instrument in the SDSS-r broadband filter. These were observed on five nights within two days of the full-Moon across two RoboPol observing seasons. We find that for 18 of the 19 patches, the uniformity in the measured normalized Stokes parameters $q$ and $u$ is within 0.2 %, with 12 patches exhibiting uniformity within 0.07 % or better for both $q$ and $u$ simultaneously, making them reliable and stable wide-field linear polarization flats. We demonstrate that the sky on bright-Moon nights is an excellent wide-field linear polarization flat source. Various combinations of the normalized Stokes parameters $q$ and $u$ can be obtained by choosing suitable locations of the sky patch with respect to the Moon

Read this paper on arXiv…

S. Maharana, S. Kiehlmann, D. Blinov, et. al.
Tue, 9 May 23
73/88

Comments: 8 pages including appendix, 6 figures and 3 tables. Submitted to Astronomy and Astrophysics for review. Comments are welcome

Extension of the Asfgrid for correcting asteroseismic large frequency separations [IMA]

http://arxiv.org/abs/2305.03221


The asteroseismic scaling relation, dnu~rho^{0.5}, linking a star’s large frequency separation, dnu, and its mean density, rho, is not exact. Yet, it provides a very useful way to obtain fundamental stellar properties. Common ways to make the relation more accurate is to apply correction factors to it. Because the corrections depend on stellar properties, such as mass, Teff, and metallicity, it is customary to interpolate these properties over stellar model grids that include both dnu, measured from adiabatic frequencies of the models, and the models’ stellar density; hence linking both sides of the scaling relation. A grid and interpolation tool widely used for this purpose, known as Asfgrid, was published by Sharma & Stello 2016. Here, we present a significant extension of Asfgrid to cover higher- and lower-mass stars and to increase the density of grid points, especially in the low-metallicity regime.

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D. Stello and S. Sharma
Mon, 8 May 23
5/63

Comments: Published in RNAAS

Searching for Quasi-Periodic Eruptions using Machine Learning [IMA]

http://arxiv.org/abs/2305.03629


Quasi-Periodic Eruptions (QPEs) are a rare phenomenon in which the X-ray emission from the nuclei of galaxies shows a series of large amplitude flares. Only a handful of QPEs have been observed but the possibility remains that there are as yet undetected sources in archival data. Given the volume of data available a manual search is not feasible, and so we consider an application of machine learning to archival data to determine whether a set of time-domain features can be used to identify further lightcurves containing eruptions. Using a neural network and 14 variability measures we are able to classify lightcurves with accuracies of greater than 94% with simulated data and greater than 98% with observational data on a sample consisting of 12 lightcurves with QPEs and 52 lightcurves without QPEs. An analysis of 83,531 X-ray detections from the XMM Serendipitous Source Catalogue allowed us to recover lightcurves of known QPE sources and examples of several categories of variable stellar objects.

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R. Webbe and A. Young
Mon, 8 May 23
8/63

Comments: 18 pages. 16 figures

Project Lyra: The Way to Go and the Launcher to Get There [IMA]

http://arxiv.org/abs/2305.03065


In preceding papers, Project Lyra has covered many possible trajectory options available to a spacecraft bound for 1I/Oumuamua, including Solar Oberth manoeuvres, Passive Jupiter encounters, Jupiter Oberths, Double Jupiter Gravitational Assists, etc. Because feasibility was the key driver for this analysis, the important question of which launcher to exploit was largely skirted in favour of adopting the most powerful options as being sufficient, though these launchers are clearly not necessary, there being alternative less capable candidates which could be utilised instead. In this paper the various launch options available to Project Lyra are addressed to allow a general overview of their capabilities. It is found that the SpaceX Super-Heavy Starship would be a game-changer for Project Lyra, especially in the context of refuelling in LEO, and furthermore a SpaceX Falcon Heavy Expendable could also be utilised. Other launchers are considered, including Ariane 6 and the future Chinese Long March 9. The importance of the V infinity Leveraging Manoeuvre (VILM) in permitting less capable launchers to nevertheless deliver a payload to Oumuamua is elaborated

Read this paper on arXiv…

A. Hibberd
Mon, 8 May 23
19/63

Comments: N/A

Site-testing at the Muztagh-ata Site.V. Nighttime Cloud Amount during the Last Five Years [IMA]

http://arxiv.org/abs/2305.03067


The clarity of nights is the major factor that should be carefully considered for optical/infrared astronomical observatories in site-testing campaigns. Cloud coverage is directly related to the amount of time available for scientific observations at observatories. In this article, we report on the results of detailed night-time cloud statistics and continuous observing me derived from ground-based all-sky cameras at the Muztagh-ata site from 2017 to 2021. Results obtained from acquisition data show that the proportion of the annual observing me at the Muztagh-ata site is 65%, and the best period with the least cloud coverage and longer continuous observing time is from September to February. We made a comparison of the monthly mean observing nights obtained from our all-sky cameras and CLARA dataset, results show that the discrepancy between them may depend on the cloud top heights. On average, this site can provide 175 clear nights and 169 nights with at least 4 hours of continuous observing time per year.

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J. Xu, G. Feng, G. Pu, et. al.
Mon, 8 May 23
33/63

Comments: 11 pages, 9 figures

Misalignment and mode mismatch error signals for higher-order Hermite-Gauss modes from two sensing schemes [IMA]

http://arxiv.org/abs/2305.03658


The locking of lasers to optical cavities is ubiquitously required in the field of precision interferometry such as Advanced LIGO to yield optimal sensitivity. Using higher-order Hermite-Gauss (HG) modes for the main interferometer beam has been a topic of recent study, due to their potential for reducing thermal noise of the test masses. It has been shown however that higher-order HG modes are more susceptible to coupling losses into optical cavities: the misalignment and mode mismatch induced power losses scale as $2n+1$ and $n^{2}+n+1$ respectively with $n$ being the mode index. In this paper we calculate analytically for the first time the alignment and mode mismatch sensing signals for arbitrary higher-order HG modes with both the traditional sensing schemes (using Gouy phase telescopes and quadrant photodetectors) and the more recently proposed radio-frequency jitter-based sensing schemes (using only single element photodiodes). We show that the sensing signals and also the signal-to-shot noise ratios for higher-order HG modes are larger than for the fundamental mode. In particular, the alignment and mode mismatch sensing signals in the traditional sensing schemes scale approximately as $\sqrt{n}$ and $n$ respectively, whereas in the jitter-based sensing schemes they scale exactly as $2n+1$ and $n^{2}+n+1$, respectively, which exactly matches the decrease in their respective tolerances. This potentially mitigates the downside of higher-order HG modes for their suffering from excessive misalignment and mode-mismatch induced power losses.

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L. Tao, A. Green and P. Fulda
Mon, 8 May 23
34/63

Comments: 11 pages 6 figures

Challenging interferometric imaging: Machine learning-based source localization from uv-plane observations [IMA]

http://arxiv.org/abs/2305.03533


In our work, we examine, for the first time, the possibility of fast and efficient source localization directly from the uvobservations, omitting the recovering of the dirty or clean images. We propose a deep neural network-based framework that takes as its input a low-dimensional vector of sampled uvdata and outputs source positions on the sky. We investigated a representation of the complex-valued input uv-data via the real and imaginary and the magnitude and phase components. We provided a comparison of the efficiency of the proposed framework with the traditional source localization pipeline based on the state-of-the-art Python Blob Detection and Source Finder (PyBDSF) method. The investigation was performed on a data set of 9164 sky models simulated using the Common Astronomy Software Applications (CASA) tool for the Atacama Large Millimeter Array (ALMA) Cycle 5.3 antenna configuration. We investigated two scenarios: (i) noise-free as an ideal case and (ii) sky simulations including noise representative of typical extra-galactic millimeter observations. In the noise-free case, the proposed localization framework demonstrates the same high performance as the state-of-the-art PyBDSF method. For noisy data, however, our new method demonstrates significantly better performance, achieving a completeness level that is three times higher for sources with uniform signal-to-noise (S/N) ratios between 1 and 10, and a high increase in completeness in the low S/N regime. Furthermore, the execution time of the proposed framework is significantly reduced (by factors about 30) as compared to traditional methods that include image reconstructions from the uv-plane and subsequent source detections.

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O. Taran, O. Bait, M. Dessauges-Zavadsky, et. al.
Mon, 8 May 23
42/63

Comments: N/A

Beam displacement tolerances on a segmented mirror for higher-order Hermite-Gauss modes [IMA]

http://arxiv.org/abs/2305.03681


Odd-indexed higher-order Hermite-Gauss (HG) modes are compatible with 4-quadrant segmented mirrors due to their intensity nulls along the principal axes, which guarantees minimum beam intensity illuminating the bond lines between the segments thus leading to low power loss. However, a misplaced HG beam can cause extra power loss due to the bright intensity spots probing the bond lines. This paper analytically and numerically studies the beam displacement tolerances on a segmented mirror for the $\mathrm{HG_{3,3}}$ mode. We conclude that for “effective” bond lines with 6 $\mu$m width, and the $\mathrm{HG_{3,3}}$ beam size chosen to guarantee 1 ppm clipping loss when centered, the beam can be rotated by roughly 1 degree or laterally displaced by 4% of its beam size while keeping the total power on the bond lines under 1 ppm. We also demonstrate that the constrained beam displacement parameter region that guarantees a given power loss limit, or the beam displacement tolerance, is inversely proportional to the bond line thickness.

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L. Tao, N. Brown and P. Fulda
Mon, 8 May 23
45/63

Comments: 4 pages, 6 pages

Advances on the classification of radio image cubes [IMA]

http://arxiv.org/abs/2305.03435


Modern radio telescopes will daily generate data sets on the scale of exabytes for systems like the Square Kilometre Array (SKA). Massive data sets are a source of unknown and rare astrophysical phenomena that lead to discoveries. Nonetheless, this is only plausible with the exploitation of intensive machine intelligence to complement human-aided and traditional statistical techniques. Recently, there has been a surge in scientific publications focusing on the use of artificial intelligence in radio astronomy, addressing challenges such as source extraction, morphological classification, and anomaly detection. This study presents a succinct, but comprehensive review of the application of machine intelligence techniques on radio images with emphasis on the morphological classification of radio galaxies. It aims to present a detailed synthesis of the relevant papers summarizing the literature based on data complexity, data pre-processing, and methodological novelty in radio astronomy. The rapid advancement and application of computer intelligence in radio astronomy has resulted in a revolution and a new paradigm shift in the automation of daunting data processes. However, the optimal exploitation of artificial intelligence in radio astronomy, calls for continued collaborative efforts in the creation of annotated data sets. Additionally, in order to quickly locate radio galaxies with similar or dissimilar physical characteristics, it is necessary to index the identified radio sources. Nonetheless, this issue has not been adequately addressed in the literature, making it an open area for further study.

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S. Ndung’u, T. Grobler, S. Wijnholds, et. al.
Mon, 8 May 23
56/63

Comments: 21 page review paper submitted to New astronomy reviews journal for review

Spectro-polarimetry at the Pic du Midi Turret Dome and new observations of the solar CaII K line [IMA]

http://arxiv.org/abs/2305.03345


We summarize in this paper the spectro-polarimetric methods used at the Pic du Midi Turret Dome in spectroscopic or imagery mode. The polarimeters and spectrograph allow the cartography of solar magnetic fields at high spatial resolution through the Zeeman effect or measurements of the unresolved turbulent magnetic fields in the quiet Sun through the Hanle effect. We describe in this paper the optical capabilities of the successive versions of the polarimeters operating since 2003, and we present new results of magnetic field analysis with the CaII K 3933.7 {\AA} spectral line.

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J. Malherbe and T. Roudier
Mon, 8 May 23
61/63

Comments: N/A

Snapshot Averaged Matrix Pencil Method (SAM) For Direction of Arrival Estimation [IMA]

http://arxiv.org/abs/2305.02617


The estimation of the direction of electromagnetic (EM) waves from a radio source using electrically short antennas is one of the challenging problems in the field of radio astronomy. In this paper we have developed an algorithm which performs better in direction and polarization estimations than the existing algorithms. Our proposed algorithm Snapshot Averaged Matrix Pencil Method (SAM) is a modification to the existing Matrix Pencil Method (MPM) based Direction of Arrival (DoA) algorithm. In general, MPM estimates DoA of the incoherent EM waves in the spectra using unitary transformations and least square method (LSM). Our proposed SAM modification is made in context to the proposed Space Electric and Magnetic Sensor (SEAMS) mission to study the radio universe below 16 MHz. SAM introduces a snapshot averaging method to improve the incoherent frequency estimation improving the accuracy of estimation. It can also detect polarization to differentiate between Right Hand Circular Polarlization (RHCP), Right Hand Elliptical Polarlization (RHEP), Left Hand Circular Polarlization (LHCP), Left Hand Elliptical Polarlization (LHEP) and Linear Polarlization (LP). This paper discusses the formalism of SAM and shows the initial results of a scaled version of a DoA experiment at a resonant frequency of ~72 MHz.

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H. Tanti, A. Datta and S. Ananthakrishnan
Fri, 5 May 23
5/67

Comments: N/A

Effect of Earth-Moon's gravity on TianQin's range acceleration noise. III. An analytical model [IMA]

http://arxiv.org/abs/2305.02539


TianQin is a proposed space-based gravitational wave detector designed to operate in circular high Earth orbits. As a sequel to [Zhang et al. Phys. Rev. D 103, 062001 (2021)], this work provides an analytical model to account for the perturbing effect of the Earth’s gravity field on the range acceleration noise between two TianQin satellites. For such an “orbital noise,” the Earth’s contribution dominates above $5\times 10^{-5}$ Hz in the frequency spectrum, and the noise calibration and mitigation, if needed, can benefit from in-depth noise modeling. Our model derivation is based on Kaula’s theory of satellite gravimetry with Fourier-style decomposition, and uses circular reference orbits as an approximation. To validate the model, we compare the analytical and numerical results in two main scenarios. First, in the case of the Earth’s static gravity field, both noise spectra are shown to agree well with each other at various orbital inclinations and radii, confirming our previous numerical work while providing more insight. Second, the model is extended to incorporate the Earth’s time-variable gravity. Particularly relevant to TianQin, we augment the formulas to capture the disturbance from the Earth’s free oscillations triggered by earthquakes, of which the mode frequencies enter TianQin’s measurement band above 0.1 mHz. The analytical model may find applications in gravity environment monitoring and noise-reduction pipelines for TianQin.

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L. Jiao and X. Zhang
Fri, 5 May 23
19/67

Comments: 16 pages, 9 figures, accepted by Phys. Rev. D

Multi-Image X-ray Interferometer Module: I. design concept and proof-of-concept experiments with fine-pitch slits [IMA]

http://arxiv.org/abs/2305.03050


We propose a novel x-ray imaging system, Multi-Image X-ray Interferometer Module (MIXIM), with which a very high angular resolution can be achieved even with a small system size. MIXIM is composed of equally-spaced multiple slits and an x-ray detector, and its angular resolution is inversely proportional to the distance between them. Here we report our evaluation experiments of MIXIM with a newly adopted CMOS sensor with a high spatial resolution of 2.5 {\mu}m. Our previous experiments with a prototype MIXIM were limited to one-dimensional imaging, and more importantly, the achieved angular resolution was only {\sim}1″, severely constrained due to the spatial resolution of the adopted sensor with a pixel size of 4.25 {\mu}m. By contrast, one-dimensional images obtained in this experiment had a higher angular resolution of 0.5″ when a configured system size was only {\sim}1 m, which demonstrates that MIXIM can simultaneously realize a high angular resolution and compact size. We also successfully obtained a two-dimensional profile of an x-ray beam for the first time for MIXIM by introducing a periodic pinhole mask. The highest angular resolution achieved in our experiments is smaller than 0.1″ with a mask-sensor distance of 866.5 cm, which shows the high scalability of MIXIM.

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K. Asakura, K. Hayashida, T. Kawabata, et. al.
Fri, 5 May 23
22/67

Comments: 33 pages, 14 figures, 2 tables, accepted for publication in JATIS

Demonstrating repetitive non-destructive readout (RNDR) with SiSeRO devices [IMA]

http://arxiv.org/abs/2305.01900


We demonstrate so-called repetitive non-destructive readout (RNDR) for the first time on a Single electron Sensitive Readout (SiSeRO) device. SiSeRO is a novel on-chip charge detector output stage for charge-coupled device (CCD) image sensors, developed at MIT Lincoln Laboratory. This technology uses a p-MOSFET transistor with a depleted internal gate beneath the transistor channel. The transistor source-drain current is modulated by the transfer of charge into the internal gate. RNDR was realized by transferring the signal charge non-destructively between the internal gate and the summing well (SW), which is the last serial register. The advantage of the non-destructive charge transfer is that the signal charge for each pixel can be measured at the end of each transfer cycle and by averaging for a large number of measurements ($\mathrm{N_{cycle}}$), the total noise can be reduced by a factor of 1/$\mathrm{\sqrt{N_{cycle}}}$. In our experiments with a prototype SiSeRO device, we implemented nine ($\mathrm{N_{cycle}}$ = 9) RNDR cycles, achieving around 2 electron readout noise (equivalent noise charge or ENC) with spectral resolution close to the fano limit for silicon at 5.9 keV. These first results are extremely encouraging, demonstrating successful implementation of the RNDR technique in SiSeROs. They also lay foundation for future experiments with more optimized test stands (better temperature control, larger number of RNDR cycles, RNDR-optimized SiSeRO devices) which should be capable of achieving sub-electron noise sensitivities. This new device class presents an exciting technology for next generation astronomical X-ray telescopes requiring very low-noise spectroscopic imagers. The sub-electron sensitivity also adds the capability to conduct in-situ absolute calibration, enabling unprecedented characterization of the low energy instrument response.

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T. Chattopadhyay, S. Herrmann, P. Orel, et. al.
Thu, 4 May 23
46/60

Comments: Under review in Journal of Astronomical Telescopes, Instruments, and Systems (JATIS). arXiv admin note: text overlap with arXiv:2208.01082

Schedule optimization for transiting exoplanet observations with NASA's Pandora SmallSat mission [IMA]

http://arxiv.org/abs/2305.02285


Pandora is an upcoming NASA SmallSat mission that will observe transiting exoplanets to study their atmospheres and the variability of their host stars. Efficient mission planning is critical for maximizing the science achieved with the year-long primary mission. To this end, we have developed a scheduler based on a metaheuristic algorithm that is focused on tackling the unique challenges of time-constrained observing missions, like Pandora. Our scheduling algorithm combines a minimum transit requirement metric, which ensures we meet observational requirements, with a `quality’ metric that considers three factors to determine the scientific quality of each observation window around an exoplanet transit (defined as a visit). These three factors are: observing efficiency during a visit, the amount of the transit captured by the telescope during a visit, and how much of the transit captured is contaminated by a coincidental passing of the observatory through the South Atlantic Anomaly. The importance of each of these factors can be adjusted based on the needs or preferences of the science team. Utilizing this schedule optimizer, we develop and compare a few schedules with differing factor weights for the Pandora SmallSat mission, illustrating trade-offs that should be considered between the three quality factors. We also find that under all scenarios probed, Pandora will not only be able to achieve its observational requirements using the planets on the notional target list but will do so with significant time remaining for ancillary science.

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T. Foote, T. Barclay, C. Hedges, et. al.
Thu, 4 May 23
51/60

Comments: 35 pages, 7 figures. Submitted to JATIS, SPIE. Python code is available at: this https URL

The Dark Energy Survey Six-Year Calibration Star Catalog [IMA]

http://arxiv.org/abs/2305.01695


This Technical Note presents a catalog of calibrated reference stars that was generated by the Forward Calibration Method (FGCM) pipeline (arXiv:1706.01542) as part of the FGCM photometric calibration of the full Dark Energy Survey (DES) 6-Year data set (Y6). This catalog provides DES grizY magnitudes for 17 million stars with i-band magnitudes mostly in the range 16 < i < 21 spread over the full DES footprint covering 5000 square degrees over the Southern Galactic Cap at galactic latitudes b < -20 degrees (plus a few outlying fields disconnected from the main survey footprint). These stars are calibrated to a uniformity of better than 1.8 milli-mag (0.18%) RMS over the survey area. The absolute calibration of the catalog is computed with reference to the STISNIC.007 spectrum of the Hubble Space Telescope CalSpec standard star C26202; including systematic errors, the absolute flux system is known at the approximately 1% level. As such, these stars provide a useful reference catalog for calibrating grizY-band or grizY-like band photometry in the Southern Hemisphere, particularly for observations within the DES footprint.

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E. Rykoff, D. Tucker, D. Burke, et. al.
Thu, 4 May 23
60/60

Comments: 21 pages, 15 figures, Fermilab Technical Note. Official Data Access Site: this https URL ; Temporary Data Access Site: this https URL

Cryogenic payloads for the Einstein Telescope – Baseline design with heat extraction, suspension thermal noise modelling and sensitivity analyses [IMA]

http://arxiv.org/abs/2305.01419


The Einstein Telescope (ET) is a third generation gravitational wave detector that includes a room-temperature high-frequency (ET-HF) and a cryogenic low-frequency laser interferometer (ET-LF). The cryogenic ET-LF is crucial for exploiting the full scientific potential of ET. We present a new baseline design for the cryogenic payload that is thermally and mechanically consistent and compatible with the design sensitivity curve of ET. The design includes two options for the heat extraction from the marionette, based on a monocrystalline high-conductivity marionette suspension fiber and a thin-wall titanium tube filled with static He-II, respectively. Following a detailed description of the design options and the suspension thermal noise (STN) modelling, we present the sensitivity curves of the two baseline designs, discuss the influence of various design parameters on the sensitivity of ET-LF and conclude with an outlook to future R&D activities.

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X. Koroveshi, L. Busch, E. Majorana, et. al.
Wed, 3 May 23
2/67

Comments: 20 pages, Article to be published/submitted in Physical Review D – Journal

Analytical Fitting of Gamma-ray Photopeaks in Germanium Cross Strip Detectors [IMA]

http://arxiv.org/abs/2305.01544


In an ideal germanium detector, fully-absorbed monoenergetic gamma-rays will appear in the measured spectrum as a narrow peak, broadened into a Gaussian of width determined only by the statistical properties of charge cloud generation and the electronic noise of the readout electronics. Multielectrode detectors complicate this picture. Broadening of the charge clouds as they drift through the detector will lead to charge sharing between neighboring electrodes and, inevitably, low-energy tails on the photopeak spectra. We simulate charge sharing in our germanium cross strip detectors in order to reproduce the low-energy tails due to charge sharing. Our goal is to utilize these simulated spectra to develop an analytical fit (shape function) for the spectral lines that provides a robust and high-quality fit to the spectral profile, reliably reproduces the interaction energy, noise width, and the number of counts in both the true photopeak and the low-energy tail, and minimizes the number of additional parameters. Accurate modeling of the detailed line profiles is crucial for both calibration of the detectors as well as scientific interpretation of measured spectra.

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S. Boggs and S. Pike
Wed, 3 May 23
8/67

Comments: Submitted to NIM A

Simulated recovery of LEO objects using sCMOS blind stacking [IMA]

http://arxiv.org/abs/2305.01415


We present the methodology and results of a simulation to determine the recoverability of LEO objects using a blind stacking technique. The method utilises sCMOS and GPU technology to inject and recover LEO objects in real observed data. We explore the target recovery fraction and pipeline run-time as a function of three optimisation parameters; number of frames per data-set, exposure time, and binning factor. Results are presented as a function of magnitude and velocity. We find that target recovery using blind stacking is significantly more complete, and can reach fainter magnitudes, than using individual frames alone. We present results showing that, depending on the combination of optimisation parameters, recovery fraction is up to 90% of detectable targets for magnitudes up to 13.5, and then falls off steadily up to a magnitude limit around 14.5. Run-time is shown to be a few multiples of the observing time for the best combinations of optimisation parameters, approaching real-time processing.

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B. Cooke, P. Chote, D. Pollacco, et. al.
Wed, 3 May 23
20/67

Comments: 14 pages, 14 figures. Accepted for publication in Advances in Space Research (ASR)

Interpretable Machine Learning for Science with PySR and SymbolicRegression.jl [IMA]

http://arxiv.org/abs/2305.01582


PySR is an open-source library for practical symbolic regression, a type of machine learning which aims to discover human-interpretable symbolic models. PySR was developed to democratize and popularize symbolic regression for the sciences, and is built on a high-performance distributed back-end, a flexible search algorithm, and interfaces with several deep learning packages. PySR’s internal search algorithm is a multi-population evolutionary algorithm, which consists of a unique evolve-simplify-optimize loop, designed for optimization of unknown scalar constants in newly-discovered empirical expressions. PySR’s backend is the extremely optimized Julia library SymbolicRegression.jl, which can be used directly from Julia. It is capable of fusing user-defined operators into SIMD kernels at runtime, performing automatic differentiation, and distributing populations of expressions to thousands of cores across a cluster. In describing this software, we also introduce a new benchmark, “EmpiricalBench,” to quantify the applicability of symbolic regression algorithms in science. This benchmark measures recovery of historical empirical equations from original and synthetic datasets.

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M. Cranmer
Wed, 3 May 23
23/67

Comments: 24 pages, 5 figures, 3 tables. Feedback welcome. Paper source found at this https URL ; PySR at this https URL ; SymbolicRegression.jl at this https URL

Strategy for Dynamic Wisp Removal in James Webb Space Telescope NIRCam Images [IMA]

http://arxiv.org/abs/2305.01175


The James Webb Space Telescope (JWST) near-infrared camera (NIRCam) has been found to exhibit serious wisp-like structures in four of its eight short-wavelength detectors. The exact structure and strength of these wisps is highly variable with the position and orientation of JWST, so the use of static templates is non-optimal. Here we investigate a dynamic strategy to mitigate these wisps using long-wavelength reference images. Based on a suite of experiments where we embed a worst-case scenario median-stacked wisp into wisp-free images, we define suitable parameters for our wisp removal strategy. Using this setup we re-process wisp-affected public Prime Extragalactic Areas for Reionization and Lensing Science (PEARLS) data in the North Ecliptic Pole Time Domain Field (NEP-TDF) field, resulting in significant visual improvement in our detector frames and reduced noise in the final stacked images.

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A. Robotham, J. D’Silva, R. Windhorst, et. al.
Wed, 3 May 23
31/67

Comments: 16 pages, 10 figures, submitted to PASP, comments welcome

The Readiness of EVN Telescopes for the SKA-VLBI Era [IMA]

http://arxiv.org/abs/2305.01380


The application of VLBI to scientific problems has undergone a relentless expansion since its conception, yet the potential for further expansion is still large. We are on the cusp of revolutionary progress given the arrival of a host of next-generation instruments. Over the last few years the community has been working hard to ensure the SKA design includes the capability to enable multiple simultaneous tied-array beams, which is a crucial technology to deliver ultra-precise astrometry and improve survey speed capabilities. However, to reach the full potential requires that the network of antennas is upgraded to match the SKA capabilities. We identify multiple-pixel technology, on large telescopes and connected arrays, as a crucial missing component and here will make recommendations for the upgrade path of the partner EVN (and other network) telescopes. Our feasibility studies on SKA-VLBI suggest an order of magnitude improvement in the precision and also in the frequency range at which astrometry can be performed today, if the full network has the required capabilities.

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M. Rioja and R. Dodson
Wed, 3 May 23
49/67

Comments: this https URL

Fundamental cosmology from ANDES precision spectroscopy [IMA]

http://arxiv.org/abs/2305.01446


Fundamental cosmology observations, such as the detection of the redshift drift and tests of the universality of physical laws, are key science and design drivers of the ArmazoNes high Dispersion Echelle Spectrograph (ANDES), an Extremely Large Telescope instrument. While separate forecasts for each of them have been reported, we have developed Fisher Matrix based forecast tools combining both of these observables. We demonstrate the synergies between the two ANDES datasets, quantifying the improvements in cosmology and fundamental physics parameter constraints for two separate theoretical paradigms. We publicly release this forecast code, which is one of the tools for the optimisation of the ANDES observing strategy.

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C. Marques, C. Martins and C. Alves
Wed, 3 May 23
60/67

Comments: 8 pages, 3 figures, 2 tables, MNRAS (in press)

Galaxy Classification Using Transfer Learning and Ensemble of CNNs With Multiple Colour Spaces [IMA]

http://arxiv.org/abs/2305.00002


Big data has become the norm in astronomy, making it an ideal domain for computer science research. Astronomers typically classify galaxies based on their morphologies, a practice that dates back to Hubble (1936). With small datasets, classification could be performed by individuals or small teams, but the exponential growth of data from modern telescopes necessitates automated classification methods.
In December 2013, Winton Capital, Galaxy Zoo, and the Kaggle team created the Galaxy Challenge, which tasked participants with developing models to classify galaxies. The Kaggle Galaxy Zoo dataset has since been widely used by researchers. This study investigates the impact of colour space transformation on classification accuracy and explores the effect of CNN architecture on this relationship. Multiple colour spaces (RGB, XYZ, LAB, etc.) and CNN architectures (VGG, ResNet, DenseNet, Xception, etc.) are considered, utilizing pre-trained models and weights. However, as most pre-trained models are designed for natural RGB images, we examine their performance with transformed, non-natural astronomical images.
We test our hypothesis by evaluating individual networks with RGB and transformed colour spaces and examining various ensemble configurations. A minimal hyperparameter search ensures optimal results. Our findings indicate that using transformed colour spaces in individual networks yields higher validation accuracy, and ensembles of networks and colour spaces further improve accuracy.
This research aims to validate the utility of colour space transformation for astronomical image classification and serve as a benchmark for future studies.

Read this paper on arXiv…

Y. Andrew
Tue, 2 May 23
12/57

Comments: Master’s Thesis

Breaking the 10 mW/pixel Limit for Kinetic Inductance Detector Readout Electronics [IMA]

http://arxiv.org/abs/2305.00928


We demonstrate a prototype kinetic inductance detector (KID) readout system that uses less than 10 mW per pixel. The CCAT-prime RFSoC based readout is capable of reading four independent detector networks of up to 1000 KIDs each. The power dissipation was measured to be less than 40 W while running multi-tone combs on all four channels simultaneously. The system was also used for the first time to perform sweeps and resonator identification on a prototype 280 GHz array.

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A. Sinclair, J. Burgoyne, Y. Li, et. al.
Tue, 2 May 23
16/57

Comments: to appear in the ISSTT 2022 conference proceedings

A data science platform to enable time-domain astronomy [IMA]

http://arxiv.org/abs/2305.00108


SkyPortal is an open-source platform designed to efficiently discover interesting transients, manage follow-up, perform characterization, and visualize the results, all in one application. By enabling fast access to archival and catalog data, cross-matching heterogeneous data streams, and the triggering and monitoring of on-demand observations for further characterization, SkyPortal has been operating at scale for > 2 yr for the Zwicky Transient Facility Phase II community, with hundreds of users, containing tens of millions of time-domain sources, interacting with dozens of telescopes, and enabling community reporting. While SkyPortal emphasizes rich user experiences (UX) across common frontend workflows, recognizing that scientific inquiry is increasingly performed programmatically, SkyPortal also surfaces an extensive and well-documented API system. From backend and frontend software to data science analysis tools and visualization frameworks, the SkyPortal design emphasizes the re-use and leveraging of best-in-class approaches, with a strong extensibility ethos. For instance, SkyPortal now leverages ChatGPT large-language models (LLMs) to automatically generate and surface source-level human-readable summaries. With the imminent re-start of the next-generation of gravitational wave detectors, SkyPortal now also includes dedicated multi-messenger features addressing the requirements of rapid multi-messenger follow-up: multi-telescope management, team/group organizing interfaces, and cross-matching of multi-messenger data streams with time-domain optical surveys, with interfaces sufficiently intuitive for the newcomers to the field. (abridged)

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M. Coughlin, J. Bloom, G. Nir, et. al.
Tue, 2 May 23
19/57

Comments: N/A

A Unified $p_\mathrm{astro}$ for Gravitational Waves: Consistently Combining Information from Multiple Search Pipelines [IMA]

http://arxiv.org/abs/2305.00071


Recent gravitational-wave transient catalogs have used $p_\mathrm{astro}$, the probability that a gravitational-wave candidate is astrophysical, to select interesting candidates for further analysis. Unlike false alarm rates, which exclusively capture the statistics of the instrumental noise triggers, $p_\mathrm{astro}$ incorporates the rate at which triggers are generated by both astrophysical signals and instrumental noise in estimating the probability that a candidate is astrophysical. Multiple search pipelines can independently calculate $p_\mathrm{astro}$, each employing a specific data reduction. While the range of $p_\mathrm{astro}$ results can help indicate the range of uncertainties in its calculation, it complicates interpretation and subsequent analyses. We develop a statistical formalism to calculate a $\textit{unified } p_\mathrm{astro}$ for gravitational-wave candidates, consistently accounting for triggers from all pipelines, thereby incorporating extra information about a signal that is not available with any one single pipeline. We demonstrate the properties of this method using a toy model and by application to the publicly available list of gravitational-wave candidates from the first half of the third LIGO–Virgo–KAGRA observing run. Adopting a unified $p_\mathrm{astro}$ for future catalogs would provide a simple and easy-to-interpret selection criterion that incorporates a more complete understanding of the strengths of the different search pipelines

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S. Banagiri, C. Berry, G. Davies, et. al.
Tue, 2 May 23
23/57

Comments: 18 pages, 5 figures, 1 table

Speckle Interferometry with CMOS Detector [IMA]

http://arxiv.org/abs/2305.00451


In 2022 we carried out an upgrade of the speckle polarimeter (SPP) — the facility instrument of the 2.5-m telescope of the Caucasian Observatory of the SAI MSU. During the overhaul, CMOS Hamamatsu ORCA-Quest qCMOS C15550-20UP was installed as the main detector, some drawback of the previous version of the instrument were eliminated. In this paper, we present a description of the instrument, as well as study some features of the CMOS detector and ways to take them into account in speckle interferometric processing. Quantitative comparison of CMOS and EMCCD in the context of speckle interferometry is performed using numerical simulation of the detection process. Speckle interferometric observations of 25 young variable stars are given as an example of astronomical result. It was found that BM And is a binary system with a separation of 273 mas. The variability of the system is dominated by the brightness variations of the main component. A binary system was also found in NSV 16694 (TYC 120-876-1). The separation of this system is 202 mas.

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I. Strakhov, B. Safonov and D. Cheryasov
Tue, 2 May 23
33/57

Comments: 24 pages, 27 figures. Minor style differences with respect to version accepted to Astrophys. Bull. V. 78, no. 2

BlueWalker 3 Satellite Brightness Characterized and Modeled [IMA]

http://arxiv.org/abs/2305.00831


The BlueWalker 3 (BW3) satellite was folded into a compact object when launched on 2022 September 11. The spacecraft’s apparent visual magnitude initially ranged from about 4 to 8. Observations on November 11 revealed that the brightness increased by 4 magnitudes which indicated that the spacecraft had deployed into a large flat-panel shape. The satellite then faded by several magnitudes in December before returning to its full luminosity; this was followed by additional faint periods in 2023 February and March. We discuss the probable cause of the dimming phenomena and identify a geometrical circumstance where the satellite is abnormally bright. The luminosity of BW3 can be represented with a brightness model which is based on the satellite shape and orientation as well as a reflection function having Lambertian and pseudo-specular components. Apparent magnitudes are most frequently between 2.0 and 3.0. When BW3 is near zenith the magnitude is about 1.4.

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A. Mallama, R. Cole, S. Tilley, et. al.
Tue, 2 May 23
45/57

Comments: N/A

Directional Sensitivity of the NEWSdm Experiment to Cosmic Ray Boosted Dark Matter [IMA]

http://arxiv.org/abs/2305.00112


We present a study of a directional search for Dark Matter boosted forward when scattered by cosmic-ray nuclei, using a module of the NEWSdm experiment. The boosted Dark Matter flux at the edge of the Earth’s atmosphere is expected to be pointing to the Galactic Center, with a flux 15 to 20 times larger than in the transverse direction.
The module of the NEWSdm experiment consists of a 10 kg stack of Nano Imaging Trackers, i.e.~newly developed nuclear emulsions with AgBr crystal sizes down to a few tens of nanometers. The module is installed on an equatorial telescope. The relatively long recoil tracks induced by boosted Dark Matter, combined with the nanometric granularity of the emulsion, result in an extremely low background. This makes an installation at the INFN Gran Sasso laboratory, both on the surface and underground, viable. A comparison between the two locations is made. The angular distribution of nuclear recoils induced by boosted Dark Matter in the emulsion films at the surface laboratory is expected to show an excess with a factor of 3.5 in the direction of the Galactic Center. This excess allows for a Dark Matter search with directional sensitivity. The surface laboratory configuration prevents the deterioration of the signal in the rock overburden and it emerges as the most powerful approach for a directional observation of boosted Dark Matter with high sensitivity. We show that, with this approach, a 10 kg module of the NEWSdm experiment exposed for one year at the Gran Sasso surface laboratory can probe Dark Matter masses between 1 keV/c$^2$ and 1 GeV/c$^2$ and cross-section values down to $10^{-30}$~cm$^2$ with a directional sensitive search.

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N. Agafonova, A. Alexandrov, A. Anokhina, et. al.
Tue, 2 May 23
48/57

Comments: 15 pages, 14 figures

Matching LOFAR sources across radio bands [IMA]

http://arxiv.org/abs/2304.14829


Aims. With the recent preliminary release of the LOFAR LBA Sky Survey (LoLSS), the first wide-area, ultra-low frequency observations from LOFAR were published. Our aim is to combine this data set with other surveys at higher frequencies to study the spectral properties of a large sample of radio sources. Methods. We present a new cross-matching algorithm taking into account the sizes of the radio sources and apply it to the LoLSS-PR, LoTSS-DR1, LoTSS-DR2 (all LOFAR), TGSS-ADR1 (GMRT), WENSS (WSRT) and NVSS (VLA) catalogues. We then study the number of matched counterparts for LoLSS radio sources and their spectral properties. Results. We find counterparts for 22 607 (89.5%) LoLSS sources. The remaining 2 640 sources (10.5%) are identified either as an artefact in the LoLSS survey (3.6%) or flagged due to their closeness to bright sources (6.9%). We find an average spectral index of $\alpha = -0.77 \pm 0.18$ between LoLSS and NVSS. Between LoLSS and LoTSS-DR2 we find $\alpha = -0.71 \pm 0.31$. The average spectral index is flux density independent above $S_{54} = 181$ mJy. Comparison of the spectral slopes from LoLSS–LoTSS-DR2 with LoTSS-DR2–NVSS indicates that the probed population of radio sources exhibits evidence for a negative spectral curvature.

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L. Böhme, D. Schwarz, F. Gasperin, et. al.
Mon, 1 May 23
26/51

Comments: 13 pages, 22 figures and 2 tables. Accepted for publication in A&A

Joint machine learning and analytic track reconstruction for X-ray polarimetry with gas pixel detectors [IMA]

http://arxiv.org/abs/2304.14425


We present our study on the reconstruction of photoelectron tracks in gas pixel detectors used for astrophysical X-ray polarimetry. Our work aims to maximize the performance of convolutional neural networks (CNNs) to predict the impact point of incoming X-rays from the image of the photoelectron track. A very high precision in the reconstruction of the impact point position is achieved thanks to the introduction of an artificial sharpening process of the images. We find that providing the CNN-predicted impact point as input to the state-of-the-art analytic analysis improves the modulation factor ($\sim 1 \%$ at 3 keV and $\sim 6 \%$ at 6 keV) and naturally mitigates a subtle effect appearing in polarization measurements of bright extended sources known as “polarization leakage”.

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N. Cibrario, M. Negro, N. Moriakov, et. al.
Mon, 1 May 23
37/51

Comments: N/A

ULTRASAT: A wide-field time-domain UV space telescope [IMA]

http://arxiv.org/abs/2304.14482


The Ultraviolet Transient Astronomy Satellite (ULTRASAT) is scheduled to be launched to geostationary orbit in 2026. It will carry a telescope with an unprecedentedly large field of view (204 deg$^2$) and NUV (230-290nm) sensitivity (22.5 mag, 5$\sigma$, at 900s). ULTRASAT will conduct the first wide-field survey of transient and variable NUV sources and will revolutionize our ability to study the hot transient universe: It will explore a new parameter space in energy and time-scale (months long light-curves with minutes cadence), with an extra-Galactic volume accessible for the discovery of transient sources that is $>$300 times larger than that of GALEX and comparable to that of LSST. ULTRASAT data will be transmitted to the ground in real-time, and transient alerts will be distributed to the community in $<$15 min, enabling a vigorous ground-based follow-up of ULTRASAT sources. ULTRASAT will also provide an all-sky NUV image to $>$23.5 AB mag, over 10 times deeper than the GALEX map. Two key science goals of ULTRASAT are the study of mergers of binaries involving neutron stars, and supernovae: With a large fraction ($>$50%) of the sky instantaneously accessible, fast (minutes) slewing capability and a field-of-view that covers the error ellipses expected from GW detectors beyond 2025, ULTRASAT will rapidly detect the electromagnetic emission following BNS/NS-BH mergers identified by GW detectors, and will provide continuous NUV light-curves of the events; ULTRASAT will provide early (hour) detection and continuous high (minutes) cadence NUV light curves for hundreds of core-collapse supernovae, including for rarer supernova progenitor types.

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Y. Shvartzvald, E. Waxman, A. Gal-Yam, et. al.
Mon, 1 May 23
43/51

Comments: 40 pages, 16 figures, 3 tables. Submitted to the AAS journals

The Light Source of the TRIDENT Pathfinder Experiment [IMA]

http://arxiv.org/abs/2304.14608


In September 2021, a site scouting mission known as the TRIDENT pathfinder experiment (TRIDENT EXplorer, T-REX for short) was conducted in the South China Sea with the goal of envisaging a next-generation multi-cubic-kilometer neutrino telescope. One of the main tasks is to measure the \textit{in-situ} optical properties of seawater at depths between $2800~\mathrm{m}$ and $3500~\mathrm{m}$, where the neutrino telescope will be instrumented. To achieve this, we have developed a light emitter module equipped with a clock synchronization system to serve as the light source, which could be operated in pulsing and steady modes. Two light receiver modules housing both photomultiplier tubes (PMTs) and cameras are employed to detect the photons emitted by the light source. This paper presents the instrumentation of the light source in T-REX, including its design, calibration, and performance.

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W. Li, X. Liu, W. Tian, et. al.
Mon, 1 May 23
49/51

Comments: N/A

IDEFIX: a versatile performance-portable Godunov code for astrophysical flows [IMA]

http://arxiv.org/abs/2304.13746


Exascale super-computers now becoming available rely on hybrid energy-efficient architectures that involve an accelerator such as Graphics Processing Units (GPU). Leveraging the computational power of these machines often means a significant rewrite of the numerical tools each time a new architecture becomes available. To address these issues, we present Idefix, a new code for astrophysical flows that relies on the Kokkos meta-programming library to guarantee performance portability on a wide variety of architectures while keeping the code as simple as possible for the user. Idefix is based on a Godunov finite-volume method that solves the non-relativistic HD and MHD equations on various grid geometries. Idefix includes a wide choice of solvers and several additional modules (constrained transport, orbital advection, non-ideal MHD) allowing users to address complex astrophysical problems. Idefix has been successfully tested on Intel and AMD CPUs (up to 131 072 CPU cores on Irene-Rome at TGCC) as well as NVidia and AMD GPUs (up to 1024 GPUs on Adastra at CINES). Idefix achieves more than 1e8 cell/s in MHD on a single NVidia V100 GPU and 3e11 cell/s on 256 Adastra nodes (1024 GPUs) with 95% parallelization efficiency (compared to a single node). For the same problem, Idefix is up to 6 times more energy efficient on GPUs compared to Intel Cascade Lake CPUs. Idefix is now a mature exascale-ready open-source code that can be used on a large variety of astrophysical and fluid dynamics applications.

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G. Lesur, S. Baghdadi, G. Wafflard-Fernandez, et. al.
Fri, 28 Apr 23
20/68

Comments: 18 pages, 18 figures, 3 tables, accepted for publication in Astronomy & Astrophysics

Applied Machine-Learning Models to Identify Spectral Sub-Types of M Dwarfs from Photometric Surveys [IMA]

http://arxiv.org/abs/2304.14113


M dwarfs are the most abundant stars in the Solar Neighborhood and they are prime targets for searching for rocky planets in habitable zones. Consequently, a detailed characterization of these stars is in demand. The spectral sub-type is one of the parameters that is used for the characterization and it is traditionally derived from the observed spectra. However, obtaining the spectra of M dwarfs is expensive in terms of observation time and resources due to their intrinsic faintness. We study the performance of four machine-learning (ML) models: K-Nearest Neighbor (KNN), Random Forest (RF), Probabilistic Random Forest (PRF), and Multilayer Perceptron (MLP), in identifying the spectral sub-types of M dwarfs at a grand scale by deploying broadband photometry in the optical and near-infrared. We trained the ML models by using the spectroscopically identified M dwarfs from the Sloan Digital Sky Survey Data Release (SDSS) 7, together with their photometric colors that were derived from the SDSS, Two-Micron All-Sky Survey, and Wide-field Infrared Survey Explorer. We found that the RF, PRF, and MLP give a comparable prediction accuracy, 74%, while the KNN provides slightly lower accuracy, 71%. We also found that these models can predict the spectral sub-type of M dwarfs with ~99% accuracy within +/-1 sub-type. The five most useful features for the prediction are r-z, r-i, r-J, r-H, and g-z, and hence lacking data in all SDSS bands substantially reduces the prediction accuracy. However, we can achieve an accuracy of over 70% when the r and i magnitudes are available. Since the stars in this study are nearby (d~1300 pc for 95% of the stars), the dust extinction can reduce the prediction accuracy by only 3%. Finally, we used our optimized RF models to predict the spectral sub-types of M dwarfs from the Catalog of Cool Dwarf Targets for TESS, and we provide the optimized RF models for public use.

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S. Sithajan and S. Meethong
Fri, 28 Apr 23
22/68

Comments: 17 pages, 7 figures, 6 tables, Accepted for publication in PASP

Optimal TDI2.0 of sensitive curve for main space GW detector [IMA]

http://arxiv.org/abs/2304.14027


Time-delay interferometry (TDI) is a crucial technology for space-based gravitational wave detectors. Previous studies have identified the optimal TDI configuration for the first-generation. In this research, we used an Algebraic approach theory to describe the TDI space and employed a method to maximize the signal-to-noise ratio (SNR) to derive the optimal TDI combination for the second-generation. When this combination is used in the sensitivity curve, we observed enhancements of up to 1.91 times in the low-frequency domain and 2 to 3.5 times in the high-frequency domain compared to the Michelson combination. Furthermore, changes in the detector index significantly affect the optimization effect. We also present detection scenarios for several low-frequency gravitational wave sources. Compared to the first-generation TDI optimization, the SNR value for verification double white dwarfs (DWD) and the detection rate for DWD increase by 16.5%.

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Y. Tian and Z. Li
Fri, 28 Apr 23
28/68

Comments: 7 pages,9 figures

High-contrast detection of exoplanets with a kernel-nuller at the VLTI [IMA]

http://arxiv.org/abs/2304.14193


Context: The conventional approach to direct imaging has been the use of a single aperture coronagraph with wavefront correction via extreme adaptive optics. Such systems are limited to observing beyond an inner working (IWA) of a few {\lambda}/D. Nulling interferometry with two or more apertures will enable detections of companions at separations at and beyond the formal diffraction limit.
Aims: This paper evaluates the astrophysical potential of a kernel-nuller as the prime high-contrast imaging mode of the Very Large Telescope Interferometer (VLTI).
Methods: By taking into account baseline projection effects which are induced by Earth rotation, we introduce some diversity in the response of the nuller as a function of time. This response is depicted by transmission maps. We also determine whether we can extract the astrometric parameters of a companion from the kernel outputs, which are the primary intended observable quantities of the kernel-nuller. This then leads us to comment on the characteristics of a possible observing program for the discovery of exoplanets.
Results: We present transmission maps for both the raw nuller outputs and their subsequent kernel outputs. To further examine the properties of the kernel-nuller, we introduce maps of the absolute value of the kernel output. We also identify 38 targets for the direct detection of exoplanets with a kernel-nuller at the focus of the VLTI.
Conclusions: With continued upgrades of the VLTI infrastructure that will reduce fringe tracking residuals, a kernel-nuller would enable the detection of young giant exoplanets at separations < 10 AU, where radial velocity and transit methods are more sensitive.

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P. Chingaipe, F. Martinache, N. Cvetojevic, et. al.
Fri, 28 Apr 23
33/68

Comments: 13 pages, 12 figures

The pure-rotational and rotational-vibrational Raman spectrum of the atmosphere at an altitude of 23 km [IMA]

http://arxiv.org/abs/2304.13747


Ground-based optical astronomical observations supported by or in the vicinity of laser guide-star systems can be contaminated by Raman-scattered laser photons. Anticipating, alleviating, and correcting for the impact of this self-inflicted contamination requires a detailed knowledge of the pure-rotational and rotational-vibrational spectrum of the molecules in our atmosphere. We present a 15.3hr-deep combined spectrum of the 4LGSF’s 589nm $\approx$ 509THz sodium laser beams of Paranal observatory, acquired with the ESPRESSO spectrograph at a resolution $\lambda/\Delta\lambda\cong140’000\approx0.12$ cm$^{-1}$ and an altitude of 23 km above mean sea level. We identify 865 Raman lines over the spectral range of [3770; 7900]{\AA}$\approx$[+9540; -4315] cm$^{-1}$, with relative intensities spanning ~5 orders of magnitudes. These lines are associated to the most abundant molecules of dry air, including their isotopes: 14N14N, 14N15N, 16O16O, 16O17O, 16O18O, and 12C16O16O. The signal-to-noise of these observations implies that professional observatories can treat the resulting catalogue of Raman lines as exhaustive (for the detected molecules, over the observed Raman shift range) for the purpose of predicting/correcting/exploiting Raman lines in astronomical data.
Our observations also reveal that the four laser units of the 4LGSF do not all lase at the same central wavelength. […] The [measured] offsets […] are larger than the observed 4LGSF spectral stability of $\pm$3 MHz over hours. They remain well within the operational requirements for creating artificial laser guide-stars, but hinder the assessment of the radial velocity accuracy of ESPRESSO at the required level of 10 m/s. Altogether, our observations demonstrate how Raman lines can be exploited by professional observatories as highly-accurate, on-sky wavelength references.

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F. Vogt, A. Mehner, P. Figueira, et. al.
Fri, 28 Apr 23
35/68

Comments: 33 pages incl. appendices, 10 figures, 5 tables. Accepted for publication in Physical Review Research

Architecting Complex, Long-Lived Scientific Software [IMA]

http://arxiv.org/abs/2304.13797


Software is a critical aspect of large-scale science, providing essential capabilities for making scientific discoveries. Large-scale scientific projects are vast in scope, with lifespans measured in decades and costs exceeding hundreds of millions of dollars. Successfully designing software that can exist for that span of time, at that scale, is challenging for even the most capable software companies. Yet scientific endeavors face challenges with funding, staffing, and operate in complex, poorly understood software settings. In this paper we discuss the practice of early-phase software architecture in the Square Kilometre Array Observatory’s Science Data Processor. The Science Data Processor is a critical software component in this next-generation radio astronomy instrument. We customized an existing set of processes for software architecture analysis and design to this project’s unique circumstances. We report on the series of comprehensive software architecture plans that were the result. The plans were used to obtain construction approval in a critical design review with outside stakeholders. We conclude with implications for other long-lived software architectures in the scientific domain, including potential risks and mitigations.

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N. Ernst, J. Klein, M. Bartolini, et. al.
Fri, 28 Apr 23
39/68

Comments: published at Journal of Systems and Software as In Practice article. Data package at doi:10.5281/zenodo.7868987

Identifying Strongly Lensed Gravitational Waves with the Third-generation Detectors [IMA]

http://arxiv.org/abs/2304.13967


The joint detection of GW signals by a network of instruments will increase the detecting ability of faint and far GW signals with higher signal-to-noise ratios (SNRs), which could improve the ability of detecting the lensed GWs as well, especially for the 3rd generation detectors, e.g. Einstein Telescope (ET) and Cosmic Explorer (CE). However, identifying Strongly Lensed Gravitational Waves (SLGWs) is still challenging. We focus on the identification ability of 3G detectors in this article. We predict and analyze the SNR distribution of SLGW signals and prove only 50.6\% of SLGW pairs detected by ET alone can be identified by Lens Bayes factor (LBF), which is a popular method at present to identify SLGWs. For SLGW pairs detected by CE\&ET network, owing to the superior spatial resolution, this number rises to 87.3\%. Moreover, we get an approximate analytical relation between SNR and LBF. We give clear SNR limits to identify SLGWs and estimate the expected yearly detection rates of galaxy-scale lensed GWs that can get identified with 3G detector network.

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Z. Gao, K. Liao, L. Yang, et. al.
Fri, 28 Apr 23
47/68

Comments: 9 pages, 7 figures

Hydra II: Characterisation of Aegean, Caesar, ProFound, PyBDSF, and Selavy source finders [IMA]

http://arxiv.org/abs/2304.14357


We present a comparison between the performance of a selection of source finders using a new software tool called Hydra. The companion paper, Paper~I, introduced the Hydra tool and demonstrated its performance using simulated data. Here we apply Hydra to assess the performance of different source finders by analysing real observational data taken from the Evolutionary Map of the Universe (EMU) Pilot Survey. EMU is a wide-field radio continuum survey whose primary goal is to make a deep ($20\mu$Jy/beam RMS noise), intermediate angular resolution ($15^{\prime\prime}$), 1\,GHz survey of the entire sky south of $+30^{\circ}$ declination, and expecting to detect and catalogue up to 40 million sources. With the main EMU survey expected to begin in 2022 it is highly desirable to understand the performance of radio image source finder software and to identify an approach that optimises source detection capabilities. Hydra has been developed to refine this process, as well as to deliver a range of metrics and source finding data products from multiple source finders. We present the performance of the five source finders tested here in terms of their completeness and reliability statistics, their flux density and source size measurements, and an exploration of case studies to highlight finder-specific limitations.

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M. Boyce, A. Hopkins, S. Riggi, et. al.
Fri, 28 Apr 23
56/68

Comments: Paper accepted for publication in PASA

Hydra I: An extensible multi-source-finder comparison and cataloguing tool [IMA]

http://arxiv.org/abs/2304.14355


The latest generation of radio surveys are now producing sky survey images containing many millions of radio sources. In this context it is highly desirable to understand the performance of radio image source finder (SF) software and to identify an approach that optimises source detection capabilities. We have created Hydra to be an extensible multi-SF and cataloguing tool that can be used to compare and evaluate different SFs. Hydra, which currently includes the SFs Aegean, Caesar, ProFound, PyBDSF, and Selavy, provides for the addition of new SFs through containerisation and configuration files. The SF input RMS noise and island parameters are optimised to a 90\% ”percentage real detections” threshold (calculated from the difference between detections in the real and inverted images), to enable comparison between SFs. Hydra provides completeness and reliability diagnostics through observed-deep ($\mathcal{D}$) and generated-shallow ($\mathcal{S}$) images, as well as other statistics. In addition, it has a visual inspection tool for comparing residual images through various selection filters, such as S/N bins in completeness or reliability. The tool allows the user to easily compare and evaluate different SFs in order to choose their desired SF, or a combination thereof. This paper is part one of a two part series. In this paper we introduce the Hydra software suite and validate its $\mathcal{D/S}$ metrics using simulated data. The companion paper demonstrates the utility of Hydra by comparing the performance of SFs using both simulated and real images.

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M. Boyce, A. Hopkins, S. Riggi, et. al.
Fri, 28 Apr 23
64/68

Comments: Paper accepted for publication in PASA

Applying a temporal systematics model to vector Apodizing Phase Plate coronagraphic data: TRAP4vAPP [IMA]

http://arxiv.org/abs/2304.14063


The vector Apodizing Phase Plate (vAPP) is a pupil plane coronagraph that suppresses starlight by forming a dark hole in its point spread function (PSF). The unconventional and non-axisymmetrical PSF arising from the phase modification applied by this coronagraph presents a special challenge to post-processing techniques. We aim to implement a recently developed post-processing algorithm, temporal reference analysis of planets (TRAP) on vAPP coronagraphic data. The property of TRAP that uses non-local training pixels, combined with the unconventional PSF of vAPP, allows for more flexibility than previous spatial algorithms in selecting reference pixels to model systematic noise. Datasets from two types of vAPPs are analysed: a double grating-vAPP (dgvAPP360) that produces a single symmetric PSF and a grating-vAPP (gvAPP180) that produces two D-shaped PSFs. We explore how to choose reference pixels to build temporal systematic noise models in TRAP for them. We then compare the performance of TRAP with previously implemented algorithms that produced the best signal-to-noise ratio (S/N) in companion detections in these datasets. We find that the systematic noise between the two D-shaped PSFs is not as temporally associated as expected. Conversely, there is still a significant number of systematic noise sources that are shared by the dark hole and the bright side in the same PSF. We should choose reference pixels from the same PSF when reducing the dgvAPP360 dataset or the gvAPP180 dataset with TRAP. In these datasets, TRAP achieves results consistent with previous best detections, with an improved S/N for the gvAPP180 dataset.

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P. Liu, A. Bohn, D. Doelman, et. al.
Fri, 28 Apr 23
68/68

Comments: 15 pages, 10 figures, accepted to A&A

Detecting HI Galaxies with Deep Neural Networks in the Presence of Radio Frequency Interference [IMA]

http://arxiv.org/abs/2304.13108


In neutral hydrogen (HI) galaxy survey, a significant challenge is to identify and extract the HI galaxy signal from observational data contaminated by radio frequency interference (RFI). For a drift-scan survey, or more generally a survey of a spatially continuous region, in the time-ordered spectral data, the HI galaxies and RFI all appear as regions which extend an area in the time-frequency waterfall plot, so the extraction of the HI galaxies and RFI from such data can be regarded as an image segmentation problem, and machine learning methods can be applied to solve such problems. In this study, we develop a method to effectively detect and extract signals of HI galaxies based on a Mask R-CNN network combined with the PointRend method. By simulating FAST-observed galaxy signals and potential RFI impacts, we created a realistic data set for the training and testing of our neural network. We compared five different architectures and selected the best-performing one. This architecture successfully performs instance segmentation of HI galaxy signals in the RFI-contaminated time-ordered data (TOD), achieving a precision of 98.64% and a recall of 93.59%.

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R. Liang, F. Deng, Z. Yang, et. al.
Thu, 27 Apr 23
39/78

Comments: 17 pages, 9 figures, 1 tables. Accepted for publication in RAA

Multi-scale stamps for real-time classification of alert streams [IMA]

http://arxiv.org/abs/2304.13080


In recent years, automatic classifiers of image cutouts (also called “stamps”) have shown to be key for fast supernova discovery. The upcoming Vera C. Rubin Observatory will distribute about ten million alerts with their respective stamps each night, which it is expected to enable the discovery of approximately one million supernovae each year. A growing source of confusion for these classifiers is the presence of satellite glints, sequences of point-like-sources produced by rotating satellites or debris. The currently planned Rubin stamps will have a size smaller than the typical separation between these point sources. Thus, a larger field of view image stamp could enable the automatic identification of these sources. However, the distribution of larger field of view stamps would be limited by network bandwidth restrictions. We evaluate the impact of using image stamps of different angular sizes and resolutions for the fast classification of events (AGNs, asteroids, bogus, satellites, SNe, and variable stars), using available data from the Zwicky Transient Facility survey. We compare four scenarios: three with the same number of pixels (small field of view with high resolution, large field of view with low resolution, and a proposed multi-scale strategy) and a scenario with the full ZTF stamp that has a larger field of view and higher resolution. Our multi-scale proposal outperforms all the scenarios, with a macro f1-score of 87.39. We encourage Rubin and its Science Collaborations to consider the benefits of implementing multi-scale stamps as a possible update to the alert specification.

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I. Reyes-Jainaga, F. Förster, A. Arancibia, et. al.
Thu, 27 Apr 23
41/78

Comments: Submitted to ApJL

Onboard Science Instrument Autonomy for the Detection of Microscopy Biosignatures on the Ocean Worlds Life Surveyor [IMA]

http://arxiv.org/abs/2304.13189


The quest to find extraterrestrial life is a critical scientific endeavor with civilization-level implications. Icy moons in our solar system are promising targets for exploration because their liquid oceans make them potential habitats for microscopic life. However, the lack of a precise definition of life poses a fundamental challenge to formulating detection strategies. To increase the chances of unambiguous detection, a suite of complementary instruments must sample multiple independent biosignatures (e.g., composition, motility/behavior, and visible structure). Such an instrument suite could generate 10,000x more raw data than is possible to transmit from distant ocean worlds like Enceladus or Europa. To address this bandwidth limitation, Onboard Science Instrument Autonomy (OSIA) is an emerging discipline of flight systems capable of evaluating, summarizing, and prioritizing observational instrument data to maximize science return. We describe two OSIA implementations developed as part of the Ocean Worlds Life Surveyor (OWLS) prototype instrument suite at the Jet Propulsion Laboratory. The first identifies life-like motion in digital holographic microscopy videos, and the second identifies cellular structure and composition via innate and dye-induced fluorescence. Flight-like requirements and computational constraints were used to lower barriers to infusion, similar to those available on the Mars helicopter, “Ingenuity.” We evaluated the OSIA’s performance using simulated and laboratory data and conducted a live field test at the hypersaline Mono Lake planetary analog site. Our study demonstrates the potential of OSIA for enabling biosignature detection and provides insights and lessons learned for future mission concepts aimed at exploring the outer solar system.

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M. Wronkiewicz, J. Lee, L. Mandrake, et. al.
Thu, 27 Apr 23
69/78

Comments: 49 pages, 18 figures, submitted to The Planetary Science Journal on 2023-04-20

Multi-band Extension of the Wideband Timing Technique [IMA]

http://arxiv.org/abs/2304.13072


The wideband timing technique enables the high-precision simultaneous estimation of Times of Arrival (ToAs) and Dispersion Measures (DMs) while effectively modeling frequency-dependent profile evolution. We present two novel independent methods that extend the standard wideband technique to handle simultaneous multi-band pulsar data incorporating profile evolution over a larger frequency span to estimate DMs and ToAs with enhanced precision. We implement the wideband likelihood using the libstempo python interface to perform wideband timing in the tempo2 framework. We present the application of these techniques to the dataset of fourteen millisecond pulsars observed simultaneously in Band 3 (300 – 500 MHz) and Band 5 (1260 – 1460 MHz) of the upgraded Giant Metrewave Radio Telescope (uGMRT) as a part of the Indian Pulsar Timing Array (InPTA) campaign. We achieve increased ToA and DM precision and sub-microsecond root mean square post-fit timing residuals by combining simultaneous multi-band pulsar observations done in non-contiguous bands for the first time using our novel techniques.

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A. Paladi, C. Dwivedi, P. Rana, et. al.
Thu, 27 Apr 23
76/78

Comments: Submitted to MNRAS

On Galileo's self-portrait Mentioned by Thomas Salusbury [IMA]

http://arxiv.org/abs/2304.12320


An intriguing reference to the existence of a self-portrait by Galileo Galilei is contained in the biography of the scientist by Thomas Salusbury dated ca. 1665, of which only one incomplete and inaccessible copy exists. Galileo grew up in a Renaissance atmosphere, acquiring an artistic touch. He was a musician, a writer and also a painter, as reported by Viviani and documented by his watercolours of the Moon and drawings of solar spots. Recently a new portrait with a remarkable similarity to the portraits of Galileo Galilei by Santi di Tito (1601), Domenico Tintoretto (ca. 1604), and Furini (ca. 1612) has been found and examined using sophisticated face recognition techniques. If the identity could be confirmed, other elements, such as the young age of Galileo or the seam in the canvas revealed by infrared and X-ray analysis, may suggest a possible link with the self-portrait mentioned by Salusbury.

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P. Molaro
Wed, 26 Apr 23
29/62

Comments: 10 pages, 3 figures, Conference INSAP IX London

Enabling Exoplanet Demographics Studies with Standardized Exoplanet Survey Meta-Data [IMA]

http://arxiv.org/abs/2304.12442


Goal 1 of the National Academies of Science, Engineering and Mathematics Exoplanet Science Strategy is “to understand the formation and evolution of planetary systems as products of the process of star formation, and characterize and explain the diversity of planetary system architectures, planetary compositions, and planetary environments produced by these processes”, with the finding that “Current knowledge of the demographics and characteristics of planets and their systems is substantially incomplete.” One significant roadblock to our ongoing efforts to improve our demographics analyses is the lack of comprehensive meta-data accompanying published exoplanet surveys. The Exoplanet Program Analysis Group (ExoPAG) Science Interest Group 2: Exoplanet Demographics has prepared this document to provide guidance to survey architects, authors, referees and funding agencies as to the most valuable such data products for five different exoplanet detection techniques – transit, radial velocity, direct imaging, microlensing and astrometry. We find that making these additional data easily available would greatly enhance the community’s ability to perform robust, reproducible demographics analyses, and make progress on achieving the most important goals identified by the exoplanet and wider astronomical community.

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P. Group, 2. Demographics, J. Christiansen, et. al.
Wed, 26 Apr 23
48/62

Comments: 21 pages, final report after community feedback addressed

Morphological Classification of Extragalactic Radio Sources Using Gradient Boosting Methods [IMA]

http://arxiv.org/abs/2304.12729


The field of radio astronomy is witnessing a boom in the amount of data produced per day due to newly commissioned radio telescopes. One of the most crucial problems in this field is the automatic classification of extragalactic radio sources based on their morphologies. Most recent contributions in the field of morphological classification of extragalactic radio sources have proposed classifiers based on convolutional neural networks. Alternatively, this work proposes gradient boosting machine learning methods accompanied by principal component analysis as data-efficient alternatives to convolutional neural networks. Recent findings have shown the efficacy of gradient boosting methods in outperforming deep learning methods for classification problems with tabular data. The gradient boosting methods considered in this work are based on the XGBoost, LightGBM, and CatBoost implementations. This work also studies the effect of dataset size on classifier performance. A three-class classification problem is considered in this work based on the three main Fanaroff-Riley classes: class 0, class I, and class II, using radio sources from the Best-Heckman sample. All three proposed gradient boosting methods outperformed a state-of-the-art convolutional neural networks-based classifier using less than a quarter of the number of images, with CatBoost having the highest accuracy. This was mainly due to the superior accuracy of gradient boosting methods in classifying Fanaroff-Riley class II sources, with 3–4\% higher recall.

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A. Darya, I. Fernini, M. Vellasco, et. al.
Wed, 26 Apr 23
56/62

Comments: Accepted by The 2023 International Joint Conference on Neural Networks (IJCNN). The code and dataset used in this work are available from this https URL

The Performance of FAST with Ultra-Wide Bandwidth Receiver at 500-3300 MHz [IMA]

http://arxiv.org/abs/2304.11895


The Five-hundred-meter Aperture Spherical radio Telescope (FAST) has been running for several years. A new Ultra-Wide Bandwidth (UWB) receiver, simultaneously covering 500-3300 MHz, has been mounted in the FAST feed cabin and passed a series of observational tests. The whole UWB band is separated into four independent bands. Each band has 1048576 channels in total, resulted in a spectral resolution of 1 kHz. At 500-3300 MHz, the antenna gain is around 14.3-7.7 K/Jy, the aperture efficiency is around 0.56-0.30, the system temperature is around 88-130 K, and the HPBW is around 7.6-1.6 arcmin. The measured standard deviation of pointing accuracy is better than ~7.9 arcsec, when zenith angle (ZA) is within 26.4deg. The sensitivity and stability of the UWB receiver are confirmed to satisfy expectation by spectral observations, e.g., HI and OH. The FAST UWB receiver already has a good performance for taking sensitive observations in various scientific goals.

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C. Zhang, P. Jiang, M. Zhu, et. al.
Tue, 25 Apr 23
15/72

Comments: 11 pages, 7 figures, 2 tables, submitted to Research in Astronomy and Astrophysics

Fifteen years of millimeter accuracy lunar laser ranging with APOLLO: data reduction and calibration [IMA]

http://arxiv.org/abs/2304.11174


The Apache Point Lunar Laser-ranging Operation (APOLLO) has been collecting lunar range measurements for 15 years at millimeter accuracy. The median nightly range uncertainty since 2006 is 1.7 mm. A recently added Absolute Calibration System (ACS), providing an independent assessment of APOLLO system accuracy and the capability to correct lunar range data, revealed a 0.4% systematic error in the calibration of one piece of hardware that has been present for the entire history of APOLLO. Application of ACS-based timing corrections suggests systematic errors are reduced to < 1 mm, such that overall data accuracy and precision are both 1 mm. This paper describes the processing of APOLLO/ACS data that converts photon-by-photon range measurements into the aggregated normal points that are used for physics analyses. Additionally we present methodologies to estimate timing corrections for range data lacking contemporaneous ACS photons, including range data collected prior to installation of the ACS. We also provide access to the full 15-year archive of APOLLO normal points (2006-04-06 to 2020-12-27).

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N. Colmenares, J. Battat, D. Gonzales, et. al.
Tue, 25 Apr 23
23/72

Comments: 23 pages, 9 figures

Using multiobjective optimization to reconstruct interferometric data (I) [IMA]

http://arxiv.org/abs/2304.12107


Imaging in radioastronomy is an ill-posed inverse problem. Particularly the Event Horizon Telescope (EHT) Collaboration faces two big limitations for the existing methods when imaging the active galactic nuclei (AGN): large and expensive surveys solving the problem with different optimization parameters must be done, and only one local minima for each instance is returned. With our novel nonconvex, multiobjective optimization modeling approach, we aim to overcome these limitations. To this end we used a multiobjective version of the genetic algorithm (GA): the Multiobjective Evolutionary Algorithm Based on Decomposition, or MOEA/D. GA strategies explore the objective function by evolutionary operations to find the different local minima, and to avoid getting trapped in saddle points. First, we have tested our algorithm (MOEA/D) using synthetic data based on the 2017 Event Horizon Telescope (EHT) array and a possible EHT + next-generation EHT (ngEHT) configuration. We successfully recover a fully evolved Pareto front of non-dominated solutions for these examples. The Pareto front divides into clusters of image morphologies representing the full set of locally optimal solutions. We discuss approaches to find the most natural guess among these solutions and demonstrate its performance on synthetic data. Finally, we apply MOEA/D to observations of the black hole shadow in Messier 87 (M87) with the EHT data in 2017. MOEA/D is very flexible, faster than any other Bayesian method and explores more solutions than Regularized Maximum Likelihood methods (RML). We have done two papers to present this new algorithm: the first explains the basic idea behind multi-objective optimization and MOEA/D and it is used to recover static images, while in the second paper we extend the algorithm to allow dynamic and (static and dynamic) polarimetric reconstructions.

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H. Müller, A. Mus and A. Lobanov
Tue, 25 Apr 23
31/72

Comments: accepted for publication in A&A, both first authors have contributed equally to this work

Terzina on board NUSES: a pathfinder for EAS Cherenkov Light Detection from space [IMA]

http://arxiv.org/abs/2304.11992


In this paper we introduce the Terzina telescope as a part of the NUSES space mission. This telescope aims to detect Ultra High Energy Cosmic Rays (UHECRs) through the Cherenkov light emission from the extensive air showers (EAS) that they create in the Earth’s atmosphere. The Cherenkov photons are aligned along the shower axis inside about $\sim 0.2-1^{\circ}$, so that they become detectable by Terzina when it points towards the Earth’s limb. A sun-synchronous orbit will allow the telescope to observe only the night side of the Earth’s atmosphere. In this contribution, we focus on the description of the telescope detection goals, geometry, optical design and its photon detection camera composed of Silicon Photo-Multipliers (SiPMs). Moreover, we describe the full Monte Carlo simulation chain developed to estimate Terzina’s performance for UHECR detection. The estimate of the radiation damage and light background rates, the readout electronics and trigger logic are briefly described. Terzina will be able to study the potential for future physics missions devoted to UHECR detection and to UHE neutrino astronomy. It is a pathfinder for missions like POEMMA or future constellations of similar satellites to NUSES.

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L. Burmistrov
Tue, 25 Apr 23
37/72

Comments: N/A

Pulsar Candidate Classification Using A Computer Vision Method Combining with Convolution and Attention [IMA]

http://arxiv.org/abs/2304.11604


Artificial intelligence methods are indispensable to identifying pulsars from large amounts of candidates. We develop a new pulsar identification system that utilizes the CoAtNet to score two-dimensional features of candidates, uses a multilayer perceptron to score one-dimensional features, and uses logistic regression to judge the scores above. In the data preprocessing stage, we performed two feature fusions separately, one for one-dimensional features and the other for two-dimensional features, which are used as inputs for the multilayer perceptron and the CoAtNet respectively. The newly developed system achieves 98.77\% recall, 1.07\% false positive rate and 98.85\% accuracy in our GPPS test set.

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N. Cai, J. Han, W. Jing, et. al.
Tue, 25 Apr 23
54/72

Comments: 12 pages, 4 figures, 5 tables