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Physics Astrophysics Instrumentation and Methods for Astrophysics

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Wednesday 2 September

Instrumentation and Methods for Astrophysics

3.5-meter Segmented-Mirror Robotic Space Telescope Mission White Paper III. Key Scientific Mission: Exoplanet Science with a Coronagraph

Juhan Kim, Sang Hyun Lee, Yong-Woo Kang et al. (+22 more)

This volume defines the exoplanet science program enabled by the dedicated high-contrast coronagraph in the baseline science payload of the 3.5-meter Segmented-Mirror Robotic Space Telescope. The observatory architecture incorporates the optical interfaces, wavefront sensing and control, pointing stability, and operations software required for coronagraphic observations from the outset. The observing strategy gives priority to the nearest stellar systems because they provide the most accessible laboratories for planetary exploration and the most likely destinations of future interstellar missions. The diffraction limit sets a reflected-light horizon of roughly 10–15 pc for planets at 1 AU and roughly 50–80 pc for Jupiter analogs. Within those horizons, the telescope can image nearby giant planets, obtain reflected-light spectra of their atmospheres, survey young systems and circumstellar disks, and support the habitability and biosignature programs that larger future missions will pursue. The wide-field imager complements the coronagraph through transit photometry, occurrence-rate statistics, and long-term monitoring of stellar magnetic activity. A systematic census of the nearest stellar neighbors provides a lasting reference for exoplanet science and future space exploration.
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All authors Juhan Kim, Sang Hyun Lee, Yong-Woo Kang, Jeong-Yeol Han, Sungwook E. Hong, Bongkon Moon, Donguk Song, Juhyung Kang, Myeong-Gu Park, Sang Chul Kim, Chung-Uk Lee, Sangmo Tony Sohn, Arman Shafieloo, David Parkinson, Hong Soo Park, Dohyeong Kim, Chan Park, Jungjoo Sohn, Young-Beom Jeon, Jong-Hak Woo, Hyung Mok Lee, Hong Bae Ann, Myungkook James Jee, Mansoo Choi, Changbom Park

Instrumentation and Methods for Astrophysics

3.5-meter Segmented-Mirror Robotic Space Telescope Mission White Paper II. Key Scientific Mission: Wide-Field Cosmology and Galaxy Evolution

Juhan Kim, Yong-Woo Kang, Sang Hyun Lee et al. (+22 more)

The 3.5-meter Segmented-Mirror Robotic Space Telescope uses an image slicer for all spectroscopic observations. The planning baseline uses $R \simeq 1000$ for the wide survey and retains selectable $R \simeq 5000$ bands for precision line measurements. The central science case is a dense emission-line galaxy redshift survey for baryon acoustic oscillations and redshift-space distortions. Supernova and quasar programs exploit the stability, multiplexing, and repeatability of space operations. The supernova tier measures rest-frame U and near-ultraviolet magnitudes that separate optical twins at subgroup precision to $z \simeq 0.9$–$1.1$ in standard visits and to $z \simeq 1.3$–$1.5$ in ten-hour stacks. Every wide-survey tile receives three spectroscopic orientations, and a joint scene reconstruction uses their different overlap geometries to recover the spectra. The flagship survey covers 100–300 deg$^2$ and targets $10^6$–$3 \times 10^6$ emission-line galaxies. A deep pencil-beam tier and a supernova time-domain tier complement the wide survey. The same observations provide a census of ultra-diffuse and low-surface-brightness galaxies, map intracluster light, and test cold, self-interacting, and fuzzy dark matter through dwarf-galaxy structure and low-mass halo abundance.
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All authors Juhan Kim, Yong-Woo Kang, Sang Hyun Lee, Jeong-Yeol Han, Sungwook E. Hong, Bongkon Moon, Donguk Song, Juhyung Kang, Myeong-Gu Park, Sang Chul Kim, Chung-Uk Lee, Sangmo Tony Sohn, Arman Shafieloo, David Parkinson, Hong Soo Park, Dohyeong Kim, Chan Park, Jungjoo Sohn, Young-Beom Jeon, Jong-Hak Woo, Hyung Mok Lee, Hong Bae Ann, Myungkook James Jee, Mansoo Choi, Changbom Park

Instrumentation and Methods for Astrophysics

3.5-meter Segmented-Mirror Robotic Space Telescope Mission White Paper I. Overall Architecture and Scientific Mission

Yong-Woo Kang, Sang Hyun Lee, Juhan Kim et al. (+22 more)

We present the preliminary science concept and mission architecture of a 3.5-meter segmented-mirror robotic space telescope currently under study. The observatory is conceived as a versatile platform supporting wide-field cosmology and galaxy evolution, direct imaging and characterization of nearby planetary systems, time-domain and multi-messenger observations, compact-object studies, and Solar-System small-body science. These programs share requirements for angular resolution, photometric stability, rapid target acquisition, spectroscopy, and long-term observing efficiency. The telescope employs an 18-segment 3.5-meter primary mirror for high-angular-resolution imaging from the near-ultraviolet through the optical and near-infrared. The current baseline covers 0.2–1.5 $\mu$m, with the wavelength for diffraction-limited performance to be set by the final wavefront-error budget. Wide-field imaging is intended for deep surveys, precision photometry, and repeated monitoring over approximately 10' $\times$ 10' to 30' $\times$ 30'. Spectroscopic modes with $R \sim 1000$ and higher-resolution options approaching $R \sim 5000$ are being considered for galaxy surveys, transient classification, compact-object spectroscopy, and targeted studies. A dedicated coronagraph is also being studied for direct observations of nearby exoplanetary systems, with a current raw-contrast goal of order $10^{-8}$ and further gains expected from calibration and post-processing. Candidate mission configurations include the Sun–Earth L2 region and alternative Earth orbits, with the final choice driven by science performance, thermal stability, communications, operations, and mission cost. This paper defines the current science requirements, baseline technical configuration, and engineering trade space for further development of the 3.5mST concept.
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All authors Yong-Woo Kang, Sang Hyun Lee, Juhan Kim, Jeong-Yeol Han, Sungwook E. Hong, Bongkon Moon, Donguk Song, Juhyung Kang, Myeong-Gu Park, Sang Chul Kim, Chung-Uk Lee, Sangmo Tony Sohn, Arman Shafieloo, David Parkinson, Hong Soo Park, Dohyeong Kim, Chan Park, Jungjoo Sohn, Young-Beom Jeon, Jong-Hak Woo, Hyung Mok Lee, Hong Bae Ann, Myungkook James Jee, Mansoo Choi, Changbom Park

Instrumentation and Methods for Astrophysics

CHARA/SPICA: The six-telescope visible combiner and near-infrared fringe tracker for the CHARA Array

D. Mourard, P. Bério, C. Bailet et al. (+43 more)

The suite called Stellar Parameters and Images with a Cophased Array (SPICA) has two interferometric instruments installed at the focus of the CHARA Array located at Mount Wilson, CA. SPICA is made of SPICA-VIS, a fiber-fed six-beam visible spectrograph with three spectral resolutions, and SPICA-FT, a six-beam near-infrared fringe tracker for the fast stabilization of the fringes. SPICA is opening access to imaging in the visible domain with an unprecedented angular resolution down to 0.2 milliarcseconds. It has been designed around a large survey of fundamental parameters of stars over the Hertzsprung- Russell diagram, aiming at understanding the deviations from the standard empirical relations of stellar physics as a function of activity: limb darkening, multiplicity, rotation, winds, and environments. SPICA makes use of the advanced technologies in electron multiplying detectors in the visible and electron- avalanche photodiode arrays in the near-infrared. It benefits from the newly commissioned adaptive optics on the one-meter telescopes of the array. The modules of the visible instrument, SPICA-VIS, optimize the injection of light into single-mode fibers for spatial filtering before spectral dispersion in the image plane. The fringe tracker, SPICA-FT, performs group-delay and phase-delay tracking for six beams in the H band. SPICA-FT can use an all-in-one or ABCD encoding of the fringe signals. SPICA is operational on sky and is close to reaching the expected performance in low spectral resolution, in particular, for the Interferometric Survey of Stellar Parameters (ISSP). More work is still needed to achieve the ultimate performance in terms of sensitivity and to allow operations with higher spectral resolutions.
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All authors D. Mourard, P. Bério, C. Bailet, A. Caci, J. Dejonghe, P. Geneslay, S. Lagarde, D. Lecron, A. Meilland, F. Morand, N. Nardetto, C. Pannetier, K. Perraut, S. Rousseau, D. Salabert, N. Ebrahimkutty, R.V. Ibañez Bustos, J. Jonák, R. Ligi, H. Nowacki, F. Patru, M. Vrard, L. Bourgés, G. Mella, N. Anugu, T. ten Brummelaar, C. Farrington, D. Gies, J. Jones, R. Koehler, K. Kubiak, C. Lanthermann, R. Ligon, G. Schaefer, N. Scott, N. Turner, J. Monnier, S. Kraus, J.B. Le Bouquin, T. Gardner, M. Gutierrez, N. Ibrahim, E. Aristidi, Y. Caujolle, C. Giordano, A. Ziad

Instrumentation and Methods for Astrophysics

Searching for Gravitational Wave Events Counterparts in X-Rays by Tilting the Multiple Shells of Wolter-I Optics

John Rankin, Daniele Spiga, Paolo Conconi et al. (+5 more)

Current X-ray telescopes have a combination of field of view and angular resolution that makes it difficult to quickly localize the electromagnetic counterparts of gravitational wave events — which will become increasingly important when the LIGO and Virgo experiment will work at full sensitivity or when the Einstein Telescope and the Cosmic Explorer observatories will come online in the next decades. We investigate what X-ray optical designs could provide — in a small mission — a field of view wide enough to observe quickly the region of the sky constrained by gravitational wave detectors, and at the same time an angular resolution sufficiently good to localize these sources. We study, using ray tracing simulations, how we can optimize a Wolter-I telescope for this purpose. We find that, by appropriately tilting the shells of a Wolter-I X-ray telescope in different directions, the field of view increases, at the cost of a reduction of the on-axis performance. We draw a possible design made of two identical modules pointing at adjacent regions of the sky.
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All authors John Rankin, Daniele Spiga, Paolo Conconi, Sergio Campana, Giovanni Pareschi, Stefano Basso, Marta Maria Civitani, Vincenzo Cotroneo

Instrumentation and Methods for Astrophysics

Scientific performances of the XGIS instrument on-board THESEUS

E. Arrigoni, S. Mereghetti, R. Campana et al. (+6 more)

The Transient High Energy Sky and Early Universe Surveyor (THESEUS) satellite, currently undergoing a Phase-A study for the M7 ESA mission selection, will mainly rely on the XGIS (X and Gamma Imaging Spectrometer) instrument to discover and precisely localise gamma-ray bursts and other high-energy transients. The XGIS instrument has been designed to provide accurate sky images in a wide field of view (>2 steradians) in the 2-150 keV band, coupled to coverage of nearly half of the sky with good timing and spectroscopic capabilities up to several MeV. This will be achieved thanks to the combination of two identical cameras, based on the coded mask imaging technique, oriented to provide partially overlapping fields of view. We present the capabilities of the XGIS, focussing in particular on the sensitivity and source location accuracy. We discuss the expected scientific advances in the GRB field, estimated through detailed Monte-Carlo simulations which take into account the design of the XGIS imaging system and the properties of the GRB population at high redshifts.
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All authors E. Arrigoni, S. Mereghetti, R. Campana, C. Labanti, A. Pisapia, P. Calabretto, G. Mattioli, E. Virgilli, L. Amati

Instrumentation and Methods for Astrophysics

Demonstrating the Time-Domain Capabilities of the 4-m International Liquid Mirror Telescope: An Early Census of Transient and Variable Detections

Kumar Pranshu, Kuntal Misra, Bhavya Ailawadhi et al. (+11 more)

The PyLMT transient detection pipeline has been operational since November 2023, detecting transient and variable objects in the ILMT images in almost real time. Using the image subtraction technique, nearly 3700 CCD frames have been analyzed by the automated pipeline, generating nearly 23,000 alerts for the detection of verified transient candidates and cataloged variable sources. Around 21,000 of the alerts correspond to known MPC asteroids, nearly 2000 correspond to variable stars (including eclipsing binaries, RR Lyrae, Delta Scuti, T-Tauri, etc.), 509 correspond to variable AGNs (including QSOs, Seyfert galaxies, and blazars), 21 supernova candidates, and several other interesting candidates. We provide a concise overview of the detections and their significance, emphasizing the surveys potential contributions to a broad class of astrophysical and scientific cases. A transient detection dashboard called DART was developed using Streamlit to visualize and categorize candidates based on PyLMT and SIMBAD classifications. It includes cone-search functionality and displays key metadata, offering an intuitive interface that is publicly accessible. Our results demonstrate the viability of liquid mirror telescopes such as the ILMT for time-domain astronomy, emphasizing the important role that small-field survey facilities can play in systematic transient science programs.
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All authors Kumar Pranshu, Kuntal Misra, Bhavya Ailawadhi, Monalisa Dubey, Naveen Dukiya, Sara Filali, Paul Hickson, Priyanshi Kumari, Gokul Singh Mehra, Vibhore Negi, Jeewan C. Pandey, Anna Pospieszalska-Surdej, Jean Surdej, Sarvesh Kumar Yadav

Instrumentation and Methods for Astrophysics · Cross-listed from astro-ph.EP

Double Gravity-Assist Rendezvous Trajectory to Halley's Comet Using Deep-Space Low Thrust

Roberto Flores, Alessandro Beolchi, Chiara Pozzi et al. (+4 more)

The perihelion of comet 1P/Halley in 2061 is an excellent chance to revisit this object of outstanding scientific and cultural relevance. During its 1986 approach to the Sun, it was targeted by several flyby missions. Due to its retrograde, highly-inclined orbit, the relative velocities during the encounter were large, limiting the scientific return due to the short time spent inside the coma. A rendezvous trajectory would overcome this limitation, but the design is challenging due to the limitations of current propulsion technology. Given the lead times of spacecraft development and the long duration of the interplanetary transfer to the comet, it is imperative to start mission planning as soon as possible. We present a novel rendezvous strategy, combining unpowered Jupiter and Saturn gravity-assists with deep-space low-thrust arcs. It minimizes launch energy and propellant budget, constraining the arrival to occur before the onset of high activity. The double flyby strategy reduces the otherwise prohibitive cost of the plane change maneuver. Closed expressions for the optimal flyby geometry, together with an explicit low-thrust transcription technique, reduce the number of design parameter to three, improving computational efficiency. Crucially, this is the first rendezvous mission concept achievable with well-proven technology (standard radioisotope thermoelectric generators and a Hall-effect thruster) and compatible with several existing launchers. We describe the trajectory optimization strategy and perform a comprehensive exploration of the design space. Finally, we present two promising proof-of-concept trajectories in detail.
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All authors Roberto Flores, Alessandro Beolchi, Chiara Pozzi, Mauro Pontani, Ivano Bertini, Cesare Barbieri, Elena Fantino

Instrumentation and Methods for Astrophysics · Cross-listed from astro-ph.GA

Empirical Near-Infrared Spectral Templates from SPHEREx: Disentangling AGN and Host-Galaxy Emission

Wenke Ren, Hengxiao Guo, Zhenya Zheng et al. (+9 more)

SPHEREx conducts the first all-sky near-infrared spectral survey over 0.75-5.0 $\mu$m, spanning the transition from host-galaxy starlight to AGN-heated torus emission and enabling spectroscopic identification of active galactic nuclei (AGNs). We develop a data-driven framework combining weighted non-negative matrix factorization with forward modeling to learn empirical rest-frame templates from 2,777 normal galaxies and 1,064 AGNs in the North Ecliptic Pole (NEP) field. The resulting 14-component dictionary contains seven galaxy templates spanning stellar-population continua and nebular emission and seven AGN templates capturing emission lines and warm and hot torus continua, providing an additive, operational decomposition. Inferred near-infrared host fractions correlate with independent SDSS spectral and HSC imaging decompositions (at Pearson $r=0.68$ and $r=0.59$), comparable to the SDSS-HSC correlation ($r=0.66$) and supporting the reliability of the AGN-host separation. In the NEP deep field, the same templates recover redshifts with $|z_{\rm fit}-z_{\rm spec}| < 0.01$ for 93.0% of galaxies and 93.5% of AGNs and distinguish galaxies, narrow-line AGNs, and broad-line AGNs with 81.3% accuracy. At all-sky depth, classification retains 72.9% accuracy. The near-infrared coefficients also flag questionable DESI spectral classifications and redshifts, showing how SPHEREx complements optical spectroscopy. Learned directly from survey spectrophotometry and extending beyond the $K$ band, this empirical dictionary fills a long-standing gap in near-to-mid-infrared templates and provides a data-driven foundation for population-scale studies of AGN activity and its connection to host galaxies across the SPHEREx all-sky survey.
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All authors Wenke Ren, Hengxiao Guo, Zhenya Zheng, Minfeng Gu, Wenwen Zuo, Junxian Wang, Weida Hu, Zhen-Bo Su, Shi-Jiang Chen, Lin Long, Jiaqi Lin, Chi-Zhuo Wang

Instrumentation and Methods for Astrophysics

Simulation of the electron escape ratio for keV alpha-particle ionization tracks in liquid helium

Zihuai Hu, Junhui Liao, Zhuo Liang et al. (+6 more)

The electron escape ratio for 5.3 MeV alpha-particle ionization tracks in liquid helium under varying external electric fields has been measured in several experiments. However, to the best of our knowledge, the corresponding ratio for keV-scale alpha tracks in the same medium has not yet been reported. In this article, we demonstrate for the first time that this ratio can be accurately characterized using COMSOL-based simulations. Our simulation framework was developed in two stages. In Stage I, we aimed to verify consistency between our simulated results and published experimental data for 5.3 MeV alpha particles. Following successful verification in Stage I, we proceeded to Stage II, in which the 5.3 MeV track was replaced by 2, 5, and 10 keV tracks. Our simulated results reveal that (a) keV-scale tracks exhibit electron escape ratios approximately 1.5-2.5 times higher than that of the 5.3 MeV track, and (b) the escape ratios for all track energies (2, 5, 10 keV, and 5.3 MeV) exhibit a linear dependence on the ion number density at the simulation's T0, but not on the electron number density.
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All authors Zihuai Hu, Junhui Liao, Zhuo Liang, Guangpeng An, Zhaohua Peng, Jian Zheng, Lifeng Zhang, Lei Zhang, Yuanning Gao

Instrumentation and Methods for Astrophysics

Overview of multi-conjugate adaptive optics reconstructors

Clémentine Béchet

Multi-Conjugate Adaptive Optics (MCAO) systems aim at correcting for the atmospheric turbulence uniformly over wide-field observations. Compared to classical AO, this requires a tomographic reconstruction of the turbulence perturbations, that is to say a reconstruction of the atmosphere in its volume, and the control of several deformable mirrors optically conjugated to various altitudes. During the last two decades, many tomographic reconstructors have been proposed in the AO literature and some have been implemented on sky on existing MCAO systems. This paper presents an overview of MCAO reconstructors. Four categories of reconstructors are considered: i) the reconstructors based on interaction matrix; ii) the minimum-variance static reconstructors; iii) the 3-step recontructors and iv) the Kalman-based reconstructors. We discuss their relative advantages and drawbacks.
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Instrumentation and Methods for Astrophysics

Optimization of adaptive optics correction during observations: Algorithms and system parameters identification in closed-loop

Clémentine Béchet, Michel Tallon and Éric Thiébaut

The adaptive optics (AO) on the European Extremely Large Telescope, as well as earlier pathfinders like the Adaptive Optics Facility, at the Very Large Telescope in 2014, will no longer be stationary systems. AO is no longer isolated on a bench; some elements are directly in the optical train of the telescope, suffering environment and constrains changes during the observations. To guarantee good performance at any observing time, we investigate a self-calibration strategy. We focus here on one of the most challenging aspects: the identification of system parameters during closed-loop observations without introducing any additional disturbance. Such problem is known in the identification theory to be difficult to solve. We have recently presented (Béchet et al., AO4ELT2 Conference, 2011) an identification method for this, with promising results obtained in simulations. To consolidate these advances, we come back in the present paper to the equations and provide a theoretical analysis to justify the choice of the algorithm. We highlight the benefit of using incremental data and commands to decorrelate the disturbance. We also present 2 implementations of the method, currently studied at the European Southern Observatory.
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Instrumentation and Methods for Astrophysics

BICEP/Keck XXII: Analysis of the South Pole Atmosphere for CMB Observations

P. A. R. Ade, Z. Ahmed, M. Amiri et al. (+92 more)

The South Pole is among the driest sites on Earth, and the resulting high atmospheric transparency makes it an excellent site for millimeter-wave astronomical observations. Nevertheless, for bolometric surveys of the cosmic microwave background (CMB), fluctuations in line-of-sight water vapor drive variable atmospheric emission, which has a significant impact on survey sensitivity. We have deployed a water vapor radiometer (WVR) to characterize these fluctuations in space and time and to compare atmospheric and CMB signals with other sites. This WVR has been monitoring conditions from the South Pole over the past nine years, co-located and co-observing with the BICEP series of telescopes. In this work, we analyze the performance of the WVR and the characteristics of the South Pole atmosphere and demonstrate coherent wind-driven transport of water vapor structures across the site. We show that fluctuations in CMB detector timestreams are well correlated with fluctuations in atmospheric water vapor, providing independent justification for baseline filtering procedures used to remove these fluctuations and providing a new pathway to detect and mitigate the temperature-to-polarization leakage that currently limits the precision of ground-based CMB polarization measurements.
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All authors P. A. R. Ade, Z. Ahmed, M. Amiri, D. Barkats, D. Barron, R. Basu Thakur, I. Birdwell, C. A. Bischoff, D. Beck, J. J. Bock, V. Buza, B. Cantrall, J. R. Cheshire IV, J. Connors, J. Cornelison, M. Crumrine, A. J. Cukierman, E. Denison, L. Duband, M. A. Echter, M. Eiben, B. D. Elwood, S. Fatigoni, J. P. Filippini, A. Fortes, M. Gao, C. Giannakopoulos, N. Goeckner-Wald, D. C. Goldfinger, S. Gratton, J. A. Grayson, A. Greathouse, P. K. Grimes, G. Halal, M. Halpern, E. Hand, S. A. Harrison, S. Henderson, T. D. Hoang, J. Hubmayr, H. Hui, K. D. Irwin, J. H. Kang, K. S. Karkare, S. Kefeli, J. M. Kovac, C. Kuo, K. Lasko, K. Lau, M. Lautzenhiser, T. Liu, S. C. Mackey, N. Maher, K. G. Megerian, L. Minutolo, L. Moncelsi, Y. Nakato, H. T. Nguyen, R. O'Brien, S. N. Paine, A. Papen, A. Patel, M. A. Petroff, A. R. Polish, N. Precup, T. Prouve, C. Pryke, C. D. Reintsema, T. Romand, M. Salatino, A. Schillaci, B. Schmitt, C. D. Sheehy, B. Singari, A. Soliman, T. St. Germaine, A. Steiger, B. Steinbach, R. Sudiwala, G. Teply, K. L. Thompson, C. Tucker, A. D. Turner, C. Verges, A. G. Vieregg, A. Wandui, A. C. Weber, J. Willmert, C. L. Wong, W. L. K. Wu, H. Yang, C. Yu, L. Zeng, C. Zhang, S. Zhang

Instrumentation and Methods for Astrophysics

Lightweight Soft X-ray Imager (LSXI) with glass-based coded mask

Dali Zhang, Chao Zheng, Lu Wang et al. (+23 more)

The coded mask technique has been widely used in X-ray and Gamma-ray imagers, especially in space astronomy. However, the traditional design of coded mask imagers usually has problems with large size and heavy weight. Here, we propose a novel design for a coded mask imager made of glass based on microchannel plate (MCP) technology, making it lightweight (within 1 kg), compact, and self-supporting, which is very suitable for space exploration satellites. The design is initially demonstrated by reconstructing encoded patterns from measurements at the X-ray beamline. Monte Carlo simulations of the module integrated into a 6U CubeSat are conducted to assess its in-orbit detector performance, including sensitivity and source localization.
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All authors Dali Zhang, Chao Zheng, Lu Wang, Haopeng Li, Jinpeng Zhang, Xinqiao Li, Shaolin Xiong, Longhui Li, Zhenghua An, Sheng Yang, Xiaoqing Cong, Zhixing Ling, Hailing Qin, Xiangyang Wen, Ke Gong, Yaqing Liu, Xiaojing Liu, Xiang Ma, Xiaoyun Zhao, Yanbing Xu, Junhao Yin, Dejun Gong, Jiacong Liu, Chenwei Wang, Min Gao, Jinzhou Wang

Instrumentation and Methods for Astrophysics

A measurement-based approach to EPFD calculation, to quantify the impact of satellite mega-constellations on low-frequency radio astronomy

Steven J. Tingay, Gregory Hellbourg, Daniel Sheen et al. (+4 more)

Context: Satellite mega-constellations generate Unintended Electro-Magnetic Radiation (UEMR) impacting low frequency radio astronomy. The Radio Regulations of the International Telecommunications Union Radiocommunication Sector (ITU-R) contain the basis for addressing UEMR, but enforcement mechanisms are absent. Aims: To adapt compatibility study methods based on satellite constellation simulations, in particular the Equivalent Power Flux-Density (EPFD) framework, to radio telescope measurements. Methods: We adapt the ITU-R EPFD calculation framework to measurement data obtained from all-sky interferometric imaging. We address the conceptual differences between forward-model EPFD calculations and measurement-based approaches. In particular, we consider low frequency systems, which are typically wide field-of-view and interferometric instruments. Results: For the first time, we demonstrate that all-sky interferometric observations enable a direct adaptation of the EPFD formalism to measurement data. We thus confirm previous estimations (Di Vruno et al. 2023) that the resulting measurement-based EPFD distributions exceed the radio astronomy interference threshold levels defined in Recommendation ITU-R RA.769-2 in 50-70% of samples. These exceedance fractions are well above the 2% single-system data-loss criterion in Recommendation ITU-R RA.1513-2. Expressed using the conventional 2% compatibility margin, the corresponding margins are negative, ranging from -18.6 to -16.3 dB, equivalent to a required uniform attenuation of 16.3-18.6 dB. Conclusions: Measurement-based implementations provide a practical pathway toward verification and long-term monitoring at low radio frequencies, which could form an important component of enforceability. We suggest instrumentation approaches to support measurement.
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All authors Steven J. Tingay, Gregory Hellbourg, Daniel Sheen, Dylan Grigg, Benjamin Winkel, Federico Di Vruno, Balthasar Indermuehle

Instrumentation and Methods for Astrophysics

Scalability in Simulating a Large-Aperture, Fresnel Zone Plate Lens for a Conceptual Space Telescope

Maneesha Dushmantha De Zoysa, Yangwoo Seong, Ho Xuan Vinh et al. (+2 more)

As ambitious space telescope concepts such as ultra-lightweight planar diffractive optical elements (DOEs) emerge, validating the performance remains a major computational challenge. Conventional Fourier propagation algorithms were observed to fail at meter-class apertures due to severe memory limits caused by rigid grid-sampling requirements, and the scaled-down proxy models used for reflector telescopes cannot be applied, since scaling compresses the outermost zones that govern resolution. We benchmarked five Fourier-based propagators against a common Fresnel diffraction integral and found that only those decoupling the focal-plane grid from the input aperture converge within a 1% error threshold. With these findings, we implemented an optimized, stripe-processed Chirp Z-Transform (CZT) framework, evaluating the focal spot strictly within a fixed region of interest to reduce peak memory usage. Applied to five full-aperture configurations from 1.0 m to 5.0 m at f/# = 5, the framework predicted spatial resolution and diffraction efficiency to within 0.001% and 0.16% of analytical references, with modulation transfer function results cross-checked by two analytical extraction methods, all within 6.4 GB of memory on a single consumer-grade GPU. This simulation study represents first steps toward quantifying the expected results of ambitious space telescope concepts and aids the mission development (or selection) phase. With a highly accurate, memory-efficient validation tool, the findings obtained will be used to guide the fabrication decisions of future hardware, optical testing, and physical deployment mechanisms of large-scale diffractive telescopes.
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All authors Maneesha Dushmantha De Zoysa, Yangwoo Seong, Ho Xuan Vinh, Jae Hung Han, Hyun Jung Kim

Tuesday 1 September

Instrumentation and Methods for Astrophysics

Photon-Ring Retarded- Time Tomography: The Mahakal Phenomenon

Hina Dixit and Abhinav Chauhan

Near-critical null geodesics generate image-order channels with distinct mappings, delays, and weights, so one observer-time data set samples multiple source epochs. We organize the inverse problem by historical reach, dimension, and held-out recovery. Using continuum-noise-consistent, matrix-free Kerr/Schwarzschild operators for orders n = 0, 1, 2, we audit 12 spin-inclination geometries. At normalized SNR0 = 100, resolved orders extend anchor-connected history beyond direct imaging in all cells by 40 M, 24 M, and one 4 M grid step at inclinations 20 degrees, 50 degrees, and 75 degrees. Operational rank rises from 153 to 202 and old-age innovation from 8.29 M to 40.72 M; complete order summation retains only 9.66 M. Compact temporal support gives an exact result: temporal basis functions outside the direct retarded-time footprint generate identically zero direct columns, while higher orders can lift those old-epoch blind blocks. Direct old-structure rank is zero, while resolved orders support 38, 93, and 185 operational directions across three classes. Yet source enrichment leaves reach nearly fixed while rank fraction and singular-value stability collapse; this is the Mahakal phenomenon. Held-out tests show bounded benefit, not a movie. Resolved orders extend stable baseline-inclusive emissivity-level span from 48 M to 80 M, but that endpoint is level dominated. On 60 histories, physical morphology error falls by 13.3 percent with TSVD and 16.4 percent with ridge. Reliable two-feature recovery fails and the stable morphology interval is zero. Complete order summation yields no material morphology gain. The positive results are therefore best-case, known-geometry image-domain benchmarks under ideal order separation; SNR0 is an operator normalization, not an observation.
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Instrumentation and Methods for Astrophysics

Curving X-ray detectors for astrophysics applications

Eric D. Miller, James A. Gregory, Keith Warner et al. (+14 more)

Next-generation X-ray optics will revolutionize high-energy astrophysics, yet they present several challenges to design a complementary focal plane. In particular, the focal surface is curved, requiring many small, flat sensors to achieve a large field. We present work building on MIT Lincoln Laboratory technology to curve the sensor itself, improving image quality and reducing complexity. Applying this technology to back-illuminated, large-format CCDs having well-characterized X-ray response, we describe the process and report success curving functional BI CCDs to a 2.5-m radius of curvature, achieving RMS curvature deviations less than 1 micron. We confirm that there is no appreciable increase in dark current and that the spectroscopic performance across the 0.3-6 keV band remains excellent. These results demonstrate that curved, large-format X-ray sensors are realizable, and the process can be extended to silicon detectors with other architectures, including active pixel sensors.
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All authors Eric D. Miller, James A. Gregory, Keith Warner, Beverly LaMarr, Gregory Prigozhin, Marshall W. Bautz, Harry R. Clark, Michael J. Cooper, Kevan A. Donlon, Catherine E. Grant, WeiLin Hu, Mallory A. Jensen, Jill Juneau, Renee D. Lambert, Christopher W. Leitz, David Volfson, Douglas J. Young

Instrumentation and Methods for Astrophysics

The ViSta method for optimized stacking of broadband interferometric data in the Fourier domain

Martina Torsello, Marcella Massardi, Elisabetta Liuzzo et al. (+3 more)

We present the optimized version of ViSta, a visibility-domain stacking method that combines interferometric observations in the Fourier domain from radio to sub-millimeter wavelengths. By stacking visibilities directly and transforming them into the rest frame, ViSta enhances the signal, suppresses noise, and improves image reconstruction through extended uv-coverage. ViSta outperforms image stacking when individual sources are too faint to detect, achieving higher SNR in the low-signal and extended regime. This new optimized version features a C++/OpenMP kernel which replaces CASA demanding functions, enabling GPU acceleration while minimising memory usage and intermediate data products. The method is highly flexible, allowing stacking regardless of array configuration, spectral setup, or telescope. In the SKA era, where visibilities will not be routinely preserved, ViSta helps in assessing the information lost in the image-plane transition and in exploiting the vast amount of data still stored in interferometric archives.
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All authors Martina Torsello, Marcella Massardi, Elisabetta Liuzzo, Gayathri Gururajan, Francesca Perrotta, Andrea Lapi

Instrumentation and Methods for Astrophysics · Cross-listed from astro-ph.CO

Blast.jl: Differentiable Non-Limber Power Spectra for Joint Clustering, Shear, and CMB lensing Analyses

Sofia Chiarenza, Marco Bonici, Stefano Camera et al. (+4 more)

Upcoming large-scale structure surveys require accurate theoretical predictions for angular power spectra on the largest angular scales, where the commonly used Limber approximation breaks down and multiple relativistic and observational effects become relevant. At the same time, modern cosmological analyses increasingly rely on gradient-based inference techniques, motivating the development of fast, fully differentiable algorithms. In this work, we present a major extension of Blast.jl, a numerical toolkit for the efficient computation of non-Limber angular power spectra. Building on the Chebyshev-polynomial decomposition of the original framework, the updated algorithm incorporates redshift-space distortions, magnification bias, primordial non-Gaussianity, intrinsic alignments, CMB lensing, and the integrated Sachs-Wolfe effect, while remaining fully differentiable through custom automatic differentiation rules. Despite the increased physical complexity, the algorithm retains favorable scaling by precomputing all cosmology-independent quantities. We validate the expanded framework against brute-force integration and established cosmological codes, and provide a detailed analysis of the trade-off between computational speed and precision as a function of the algorithm hyperparameters. We demonstrate the readiness of Blast.jl for gradient-based inference through a simulated likelihood analysis with LSST Y10-like mock data, recovering unbiased cosmological and nuisance parameter constraints from a 35-parameter model using gradient-based samplers.
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All authors Sofia Chiarenza, Marco Bonici, Stefano Camera, Giulio Fabbian, Carlos García-García, Alex Krolewski, Will J. Percival

Instrumentation and Methods for Astrophysics · Cross-listed from astro-ph.GA

Virgo Filaments VIII: Characterizing the Structural Parameters of Virgo Galaxies with Machine Learning to Probe Environmental Quenching

Kim Conger, Gregory Rudnick, Rose A. Finn et al. (+9 more)

A persistent challenge in galaxy evolution involves disentangling the many correlated properties in order to isolate the effects of a galaxy's environment on its star formation history. To address this multidimensionality problem, we apply k-means clustering to 2831 galaxies in the extended regions around the Virgo cluster to define objective, reproducible subsets of structurally similar galaxies. Using measurements of size, light distribution, and stellar mass, k-means partitions these galaxies into three feature classes (FCs): dwarfs, spheroids, and large disks. In addition to being structurally different, these FCs show distinct offsets from the star-forming main sequence to $>3\sigma$ significance, with the spheroid population systematically shifted to lower star formation rates. Examining environmental dependence within each FC, we find that denser environments are associated with progressively stronger quenching. However, star formation for the dwarf and large disk galaxies is not strongly affected until the rich group and cluster environments. For the spheroid galaxies, star formation instead smoothly decreases as environment density increases. We verify that these trends are not driven by differences in Sersic index within each environment, suggesting that the effectiveness of environmental quenching depends on the galaxy's structural class. Our results speak to the utility of a simple machine learning model to create broad classes of structurally similar galaxies based on a small set of parameters, which has important implications for navigating this data rich era of astronomy.
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All authors Kim Conger, Gregory Rudnick, Rose A. Finn, Rebecca A. Koopmann, Benedetta Vulcani, Dennis Zaritsky, Gianluca Castignani, Francoise Combes, Gabriella De Lucia, Matteo Fossati, Gautam Nagaraj, Daria Zakharova

Instrumentation and Methods for Astrophysics

Learning and Predicting the Nonlinear Variability of X-ray Binaries with the Koopman Operator

Eric Miao, Ruo-Yu Shang, Kaya Mori et al. (+1 more)

X-ray variability in compact-object binaries encodes the nonlinear dynamics of corona-jet interactions and accretion disk instabilities. Standard timing techniques characterize periodic and quasi-periodic variability well, but do not model underlying nonlinear dynamics or forecast their evolution. We apply Koopman operator theory and a data-driven approximation, extended dynamic mode decomposition (EDMD), to X-ray light curves for the first time. Koopman theory represents nonlinear evolution as an infinite-dimensional linear operator $\mathcal{K}$, whose eigendecomposition separates a complex system into independently evolving linear modes. We derive that each Koopman eigenfunction contributes a Lorentzian peak to the power spectrum, giving quasi-periodic oscillations a dynamical interpretation in which process noise damps modes and broadens their peaks. In both chaotic Duffing oscillator simulations and $\sim$30 yr of RXTE ASM and MAXI monitoring of the X-ray binary 4U 1705-44, the slowest-varying eigenfunction partitions state space into low- and high-flux regimes, changing sign days to weeks before transitions become visible in the light curve. Iterating $\mathcal{K}$ additionally yields flux forecasts on days-to-weeks horizons. The strengths of this framework are its generality across linear and nonlinear systems, its intrinsic interpretability through decomposed modes carrying explicit dynamical meaning, and its predictive power from propagating learned dynamics forward. These results establish Koopman operator theory as a new frontier of astrophysical timing and help advance interpretable machine learning for scientific discovery and understanding.
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All authors Eric Miao, Ruo-Yu Shang, Kaya Mori, Reshmi Mukherjee

Instrumentation and Methods for Astrophysics · Cross-listed from astro-ph.GA

The HERON Coma Project: Exploring the low-surface-brightness frontiers in the Coma cluster

Javier Román, R. Michael Rich, Pablo M. Sánchez-Alarcón et al. (+3 more)

The technical complexity of data processing and residual instrumental systematics remain among the main barriers to reaching the faintest low-surface-brightness (LSB) regimes in the local Universe. Here, we present the HERON Coma Project, a deep $g$- and $r$-band imaging campaign on the Coma cluster carried out with the LSB-optimized 71-cm Jeanne Rich Telescope. The observing and processing strategy combines accurate flat-fielding, sky-background modeling and extended point spread function (PSF) characterization. As representative scientific applications, we explore the complex associated with the giant elliptical galaxies NGC 4839 and NGC 4816, in the southwestern region of Coma. Spatially coherent emission is recovered in direct imaging to $\mu_{\overline{g+r}}\simeq30~\mathrm{mag\,arcsec^{-2}}$, consistent with the nominal sensitivity inferred from the scaling of the background fluctuations. The PSF-deconvolved photometric profiles of NGC 4839 and NGC 4816 are traced to generalized isophotal radii of 705 and 329 kpc, reaching $\mu_{\overline{g+r}}=32.2$ and $31.6~\mathrm{mag\,arcsec^{-2}}$, with data-derived signal-to-noise ratios of 4.1 and 7.0, respectively. The agreement between direct detection and the predictions from background fluctuations provides no clear evidence of a systematics-dominated detection floor over the surface brightness range and spatial scales examined. We also assess the observational challenges involved in extending reliable measurements to still fainter surface brightness levels. The HERON Coma Project opens a new window onto the faint stellar record of the complex and ongoing assembly of Coma, while demonstrating the potential of modest ground-based telescopes with suppressed instrumental reflections to provide highly competitive measurements of extended diffuse structures. We make the final calibrated images publicly available to the community.
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All authors Javier Román, R. Michael Rich, Pablo M. Sánchez-Alarcón, Yolanda Jiménez-Teja, Chester Li, Mónica Esquide

Instrumentation and Methods for Astrophysics · Cross-listed from cs.LG

Generative Diffusion Surrogates with Analytical Variance Schedule

Patrick Reichherzer, Gianluca Gregori, David N. Hosking et al. (+1 more)

Stochastic transport describes physical systems in which an initially structured distribution spreads under unresolved forcing, scattering, or heterogeneous media. Useful surrogates for such systems should be probabilistic, time-resolved, and able to represent non-Gaussian distributional structure. Generative diffusion models, which corrupt data with Gaussian noise and learn a reverse flow back to structured states, have these properties. Their noise schedules, however, are usually chosen heuristically: image and audio generation—the canonical use cases—provide no physical clock. In transport, by contrast, the variance, or mean-square displacement, is often known from macroscopic theory or empirical scaling even when the full distribution is not. Here we prescribe the forward noising rate as the time derivative of this variance, turning generative time into a calibrated transport clock. The variance path is enforced by construction, while the learned score field represents how non-Gaussian structure inherited from entrance data is smoothed along that path, requiring no intermediate-time physical transport data. For ballistic-to-diffusive transport in turbulent plasmas, the surrogate matches test-particle distributions, reproduces the laboratory-measured variance scale, and tracks the simulated kurtosis evolution without schedule tuning, enabling calibrated emulation and likelihood-based inference.
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All authors Patrick Reichherzer, Gianluca Gregori, David N. Hosking, Subir Sarkar

Instrumentation and Methods for Astrophysics

CosmicPAH-IRDB: A Web Application for Including Anharmonicity in Simulated PAH Spectra for Astrophysics

Louan de Bentzmann, Christine Joblin, Karine Demyk et al. (+6 more)

Advances in infrared observations with the James Webb Space Telescope (JWST) call for new tools to exploit the information associated with the Aromatic Infrared Bands (AIBs), now observed in both distant galaxies and the embryos of planetary systems. The AIBs contain information about their carriers as well as the excitation conditions, making them powerful probes of the chemical and physical conditions of their environments - if their spectral information can be decoded. While large datasets of theoretical infrared spectra are becoming available, efforts have primarily focused on the contribution of chemical diversity to the AIBs. However, the results remain limited by the impact of the excitation process on the band profiles. The AIB carriers, thought to be polycyclic aromatic hydrocarbons (PAHs), are hot molecules, which affects their spectral characteristics. We report here our approach to quantify these effects empirically by collecting IR spectra - both experimental and theoretical - and studying the evolution of band positions and widths with temperature. We present our methodology, including the development of the CosmicPAH-IRDB web application and spectral database, along with the associated cosmicPAHmfit multi-component spectral fitting tool. Our philosophy emphasizes open sharing, user-friendly access, and machine readability. The web application, tool and their update are accessible via the Cosmic PAH portal (https://cosmic-pah.irap.omp.eu/)
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All authors Louan de Bentzmann, Christine Joblin, Karine Demyk, Giacomo Mulas, Dominique Toublanc, Vincent Marty, Axel Pérignon, Mickaël Boiziot, Jean-Michel Glorian

Instrumentation and Methods for Astrophysics

Amortized Opacity Marginalization Improves C/O Interval Calibration for Brown-Dwarf Retrievals

Kellen Heraty

Molecular line lists disagree at a level that measurably shifts retrieved C/O, so retrievals conditioned on a single list omit a dominant systematic from their error bars. Classical marginalization re-runs a full retrieval under K opacity realizations per object. We move that cost into simulation: while generating the training set we randomize opacities (smooth multiplicative Fourier fields in $\log\nu$ plus a discrete line-list mixture, under a deliberately broad prior informed by measured inter-list differences), so a neural posterior estimator learns an already-marginalized posterior. Conceptually, this is the amortized analogue of repeating a conventional retrieval under many plausible opacity realizations and averaging the resulting posteriors. On perturbed held-out spectra (n=2048) a standard NPE covers nominal 90% C/O intervals 43.3% of the time against 82.4% for a compute-matched marginalized network; three-seed control ensembles reach 93.2% on clean data but 61.4% under perturbation, against 89.4% marginalized, isolating the deficit as opacity-induced (TARP joint expected-coverage deviation 0.005 against 0.035 for a single control network). An axis ablation traces the gain to the continuous field (45.4% for the discrete swaps alone, 79.3% for the field alone). Applying the 105 real bad-pixel masks with median filling then collapsed the ensemble's C/O coverage from 0.901 to 0.479; retraining on the same mask distribution and pooling three such seeds returns a nominal 0.905 C/O and 0.891 overall under the full deployment path, still in simulation (n=1024, same 105 masks), at 0.21 to 0.31 of the prior width. On 105 JWST/G395H spectral products of 13 late-T/Y dwarfs, single marginalized networks bracket the Hood et al. (2024) T8 benchmark C/O where the control excludes it, a consistency check rather than a validation, at 1.6-2.6x wider intervals.
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Instrumentation and Methods for Astrophysics · Cross-listed from astro-ph.EP

Beyond Five Scale Heights: Composition- and Cloud-dependent Ariel Tier-2 Requirements for sub-Neptunes

Vigneshwaran Krishnamurthy, Nicolas B. Cowan, Misato Fukagawa et al. (+1 more)

The Ariel Mission Candidate Sample (MCS) Tier-2 requirements provide a common screening reference by assuming a clear H$_2$/He atmosphere and a five-scale-height transmission signal. We quantify how those requirements change for 197 known planets with $1.5\leq R_{\rm p}/R_\oplus<4.0$ when composition and clouds are specified explicitly. Equilibrium-chemistry transmission spectra at $1\times$, $10\times$, and $100\times$ solar metallicity are evaluated for clear atmospheres and idealized 1-mbar cloud decks, binned to the 47 AIRS Tier-2 channels, and combined with target-specific MCS-calibrated noise curves. For each atmosphere, we calculate the number of transits required for a featureless spectrum to be rejected at a $3\sigma$ confidence in at least 90% of repeated observations. The clear $1\times$-solar atmosphere closely follows the MCS prediction. At $10\times$ solar metallicity, stronger molecular opacity generally improves detectability, whereas at $100\times$ solar metallicity the increased mean molecular weight dominates and roughly doubles the required number of transits. Cloudy atmospheres follow the same non-monotonic trend but at substantially greater cost: the $1\times$-solar, 1-mbar case requires nearly an order of magnitude more transits than the MCS prediction, while the enriched cloudy cases still require several times more. Overall, in most atmospheric scenarios tested, small planets require more transits to robustly detect spectral features than listed in the MCS. A literature crossmatch further identifies Ariel targets with detected metastable helium, for which Tier-2 molecular spectra could connect lower-atmosphere composition and clouds to an extended, escaping H$_2$/He upper atmosphere.
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All authors Vigneshwaran Krishnamurthy, Nicolas B. Cowan, Misato Fukagawa, Teruyuki Hirano

Instrumentation and Methods for Astrophysics

Project management of the Canadian Hydrogen Observatory and Radio-transient Detector

Dallas Wulf, Matt Dobbs, Brian Hoff et al. (+3 more)

The Canadian Hydrogen Observatory and Radio-transient Detector (CHORD) is a new drift-scan radio interferometer operating from 300-1500 MHz, optimized for 21cm intensity mapping, 21cm galaxy detection, pulsars, and transient detection and localization. The full instrument will feature a core array of 512 six-meter dishes, plus two 64-dish outriggers at several thousand kilometer baselines. The project is nearing completion of the first 64-dish sub array, which will enable commissioning activities to begin in parallel with the remaining construction. In this presentation, we discuss the project management framework that has enabled us to navigate the logistical challenges of a fixed-budget, fixed-timeline research infrastructure project through a period of significant global economic and technological volatility.
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All authors Dallas Wulf, Matt Dobbs, Brian Hoff, Michael Rupen, Kendrick Smith, Keith Vanderlinde

Instrumentation and Methods for Astrophysics · Cross-listed from astro-ph.HE

Reconstruction of anomalous air showers with SKA-Low

Vital De Henau, Sjoerd Bouma, Justin Bray et al. (+31 more)

Double-bump showers are a surprising class of extensive air showers (EAS) predicted by Monte Carlo simulations, which, so far, no experiment has been able to directly detect. They occur when a high-energy secondary particle, the leading particle, travels significantly farther than the rest, creating a distinct double-peaked longitudinal profile. The unique radio footprint of double-bump showers, characterized by multiple pulses in the signals and interference patterns in the frequency spectra, enables reconstruction of longitudinal profiles from radio observations. With its dense antenna array and broad frequency range, SKA-Low will be the first observatory capable of detecting these features, offering a new opportunity to probe hadronic interactions and use the distinctive signatures of elements to provide new mass composition measurements. The goal of this analysis is to take the first steps toward using these radio signatures to reconstruct the relevant parameters of the longitudinal profile of a double-bump shower. We will start by explaining the radio signal of double-bump}showers compared to that of average showers. Then we will create a simple 2-point emission model to explain the interference patterns in the frequency spectra, which can be inverted to obtain rudimentary estimates of atmospheric depth of both peaks. Lastly, we implement a brute-force approach to reconstruct multiple parameters of the double bump.
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All authors Vital De Henau, Sjoerd Bouma, Justin Bray, Stijn Buitink, Arthur Corstanje, Edwin Dickinson, Tjibbe Gottmer, Brian Hare, Haoning He, Jörg Hörandel, Tim Huege, Clancy James, Mrinal Jetti, Philipp Laub, Xingyu Li, Marten Lourens, Hermann-Josef Mathes, Katie Mulrey, Anna Nelles, Subhadip Saha, Felix Schlüter, Olaf Scholten, Ralph Spencer, Christopher Sterpka, Sander ter Veen, Karen Terveer, Gia Trinh, Paulina Turekova, Darko Veberič, Keito Watanabe, Marc Waterson, Chao Zhang, Pengfei Zhang, Yi Zhang

Instrumentation and Methods for Astrophysics

HEL1OS on Aditya-L1 Mission: Operations, Data Processing and Monitoring of Sun in Hard X-rays

Ravishankar B. T., Manju Sudhakar, Srikar Paavan Tadepalli et al. (+11 more)

HEL1OS (High Energy L1 Orbiting X-ray Spectrometer) is the hard X-ray spectrometer on-board Aditya-L1 solar mission, monitoring the Sun continuously in the hard X-ray band of 8 keV to 150 keV from the vantage observation platform around the Sun-Earth Lagragian Point 1 (L1). HEL1OS was commissioned in end of October, 2023 and the final instrument configuration was set by end of June, 2024 after all the performance verifications. The instrument always operates in the event mode, and the down-linked data is processed in an automated pipeline to generate Science-ready products comprising mainly of solar spectra in 8 keV to 150 keV energy band. The data products of observations since December, 2023 are hosted on the internet with open access. This includes data from the performance verification phase of the payload operations. In this paper, the details of the commissioning and performance verification phases, all the stages of the fully automated data pipeline, and the data products of HEL1OS are discussed. Also a few scientific results are discussed to illustrate the timing and spectral capabilities of the instrument in monitoring Sun in the X-ray energy bands.
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All authors Ravishankar B. T., Manju Sudhakar, Srikar Paavan Tadepalli, Kiran Kumar Kalisetti, Madhavan R. Menon, Anand Jain, Reenu Palawat, Brajpal Singh, Rethika T., Priyanka Upadhyay, Prapti Mittal, Amit Purohit, Srikanth M., Anuj Nandi