Instrumentation and Methods for Astrophysics
The Canadian Galactic Emission Mapper (CGEM): A Cosmic Microwave Foreground Experiment
Parham Zarei, Pedro Villalba-González, Mandana Amiri et al. (+12 more)
The Canadian Galactic Emission Mapper (CGEM) is a 4-meter single-dish
radio telescope located at the Dominion
Radio Astrophysical Observatory (DRAO) in Penticton, Canada. CGEM is designed to map polarized Galactic synchrotron emission across the entire northern sky at 8-10 GHz with 1 MHz frequency resolution and 0.5 degree angular resolution. Its goal is to obtain high-fidelity, low-noise maps of polarized Galactic synchrotron radiation, at frequencies where synchrotron dominates, in order to provide a reliable template for CMB B-mode foreground cleaning. We will show on sky performance of CGEM's single-pixel azimuthally-symmetric
telescope, its coherent, dual-polarized radiometer, and show maps made from commissioning data from the first few months of operation.
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All authors Parham Zarei, Pedro Villalba-González, Mandana Amiri, Charles L. Bennett, Guinevere Berg, Mark Halpern, Gary Hinshaw, Gordon Lacy, Joshua MacEachern, Thomas J. Rennie, Shuyu van Kerkwijk, Bruce Veidt, Janet Weiland, Don Wiebe, Edward J. Wollack
Instrumentation and Methods for Astrophysics
The Hopkins Ultraviolet Telescope: A Historical and Personal Retrospective
William P. Blair
This manuscript documents the inception and development of the Hopkins Ultraviolet
Telescope (HUT) project, which was a component of the Astro Observatory payload that flew on two Spacelab shuttle missions in the 1990s. The discussion places the HUT project in the context of the times and highlights the importance of its acceptance by NASA in 1980 to the growth and development of astrophysics at the Johns Hopkins University. Personal recollections from the author, including a detailed description of the real time flight operations during each mission, provides an insiders view. The document includes a link to an online historical archive of supporting materials compiled in support of this effort.
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Instrumentation and Methods for Astrophysics
Simulation and development of astrophotonic H-band nulling beam combiner for the CHARA Array
Samantha G. Morrison, Pradip Gatkine and Michael P. Fitzgerald
Nulling interferometry is a promising method for direct detection and characterization of faint stellar companions such as
exoplanets and faint binary sources. The dominant constraint on instrument performance is instability noise from vibrations, thermal expansions, and other systematic sources. Photonic instruments have footprints of a few centimeters and enable advanced light control architectures. Astrophotonic implementations can include active phase control via Mach-Zehnder interferometers (MZIs) to actively minimize residual optical path errors at the location of beam combination. The compact size of photonic chips also makes them a promising solution for space-based applications such as the upcoming Habitable Worlds Observatory. The Center for High Angular Resolution Astronomy (CHARA) Array is equipped with the world's longest baseline in the near-infrared at 330 meters long. CHARA therefore has the most sensitive angular resolution in the near-infrared. A nuller at CHARA would have access to a novel parameter space essential for
exoplanet discovery and characterization. The first step in preparing a nulling beam combiner for CHARA is to develop compelling, realistic, and well-defined science cases. Simulation suites quantify the technical requirements to reach such science goals in their respective complex systems. The CHARA Array Response Model (CHARM) is the first-ever simulator built specifically for CHARA, opening up new pathways for instrument simulation. CHARM is a flexible simulation tool of an H-band, self-calibrated astrophotonic nulling beam combiner with active phase control for the CHARA Array. In this paper, we present an update on the development of our photonic nulling beam combiner for CHARA. We include early results from CHARM, demonstrating that the photonic nuller has the potential to detect and characterize a wide range of bright stellar companion systems.
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Instrumentation and Methods for Astrophysics
Flux jump correction in the QUBIC TES data pipeline
Belen Costanza, Lucas Merlo Azzolina, Claudia G. Scoccola et al. (+20 more)
Flux jumps occur in the readout electronics of Transition Edge Sensor (TES) detectors coupled to Superconducting
Quantum Interference Devices (SQUIDs), as a consequence of the periodic transfer function of SQUIDs in the superconducting regime. These events manifest as discontinuities in the Time Ordered Data (TOD) and can significantly degrade the quality of the measured signals. In this work, we present an automated pipeline to identify and correct flux jumps in the calibration data of the QUBIC (Q & U Bolometric Interferometer for Cosmology) instrument, designed to measure the B-mode polarization of the
Cosmic Microwave Background (CMB). Using data from multiple observation campaigns, we characterize the statistical properties of flux jumps and compare them with expectations based on the electronic configuration of the instrument. The proposed pipeline successfully corrects these events, allowing the recovery of affected data and enabling their use in subsequent CMB analysis.
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All authors Belen Costanza, Lucas Merlo Azzolina, Claudia G. Scoccola, Nahuel Miron Granese, Elia Battistelli, Jean-Christophe Hamilton, Michel Piat, Damien Prele, Steve Torchinsky, Ismail Bekkaoui, Alessandro Coppolecchia, Paolo De Bernardis, Sofia Ferazzoli, Massimo Gervasi, Luca Gomez, Sabrina Marwede, Silvia Masi, Youssef Moulane, Alessandro Paiella, Mathias Regnier, Gustavo Romero, Federico Sanchez, Ivan Queirolo
Instrumentation and Methods for Astrophysics
The promise of self-supervised and active learning for Strong Lens discovery: Astronomaly applied to KiDS
Margherita Grespan, Aprajita Verma, Michelle Lochner et al. (+3 more)
Strong gravitational lenses (SGLs) are rare systems whose discovery currently relies primarily on supervised machine learning methods trained on large simulated
datasets. We present the first application of Astronomaly:PROTEGE to SGL discovery, demonstrating that a human-in-the-loop active learning framework can efficiently identify lenses in large imaging surveys without the need for simulated training data. We consider a sample of 3.7 million bright
galaxies from the Kilo-Degree Survey (KiDS) DR4. Feature representations are extracted using a convolutional neural network pre-trained on the ImageNet
dataset and subsequently fine-tuned on KiDS data using the self-supervised Bootstrap Your Own Latent (BYOL) framework. Within the
embedding of these representations, the active learning loop of Astronomaly iteratively selects the most informative systems for expert inspection. A total of 3,000 objects are inspected across multiple rounds, yielding 34 high-quality (grade A/B) SGL candidates. On the basis that these systems occupy similar regions in the learned feature space, we expand this sample through nearest-neighbour similarity analysis. Including the active learning discoveries, we identify a total of 140 grade A/B candidates and more than 1,000 additional lower-confidence systems (grade C). Among the A/B candidates, 81 are newly identified, while approximately 22% of previously known grade A/B KiDS lenses are recovered. These results demonstrate strong potential for next-generation surveys such as Euclid, Roman, and Rubin's Legacy Survey of Space and Time. With approximately 60% of the high-quality candidates newly reported, this approach complements supervised methods by reducing reliance on simulations and enabling the discovery of a diverse population of SGLs.
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All authors Margherita Grespan, Aprajita Verma, Michelle Lochner, Koketso Mohale, Verlon Etsebeth, Duncan Bowden
Instrumentation and Methods for Astrophysics · Cross-listed from astro-ph.EP
The Venus Benchmark: Resolving Degeneracies in Terrestrial Exoplanet Spectra with DAVINCI
Stephen R. Kane, David S. Alexander, Shahid Aslam et al. (+8 more)
The characterization of terrestrial
exoplanets with thick, CO$_2$-dominated atmospheres via transmission and emission spectroscopy is limited by degeneracies between atmospheric composition, cloud structure, and surface conditions. These degeneracies are particularly acute for
planets in or near the Venus Zone, where sulfuric acid aerosol layers and deep-atmosphere opacity render the lower atmosphere and surface spectroscopically inaccessible via many optical/IR wavelengths. Venus provides the only accessible analog to such worlds, yet current knowledge of its full atmospheric profile relies on decades-old in situ data with known limitations. Here we demonstrate that the forthcoming DAVINCI (Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging) mission will provide the comprehensive, high-fidelity atmospheric profile data necessary to resolve many of these degeneracies. We quantify how atmospheric profile uncertainties translate into uncertainties in modeled transmission and thermal emission spectra of CO$_2$-dominated terrestrial worlds, and show that the spread in the modeled Venus
benchmark spectrum arising from current atmospheric profile uncertainties will decrease by factors of $\sim$4–5 for transmission and $\sim$5–15$\times$ for thermal emission after DAVINCI, providing a correspondingly improved
benchmark and prior for the modeling of
exoplanets with Venus-like atmospheres. We further demonstrate that these improvement factors are larger for the cloud-free atmospheric case, where the opacity floor is set by gas-phase processes rather than aerosols, because the pre-DAVINCI data are most discrepant in the sub-cloud region. Our results highlight the importance of Venus for the atmospheric characterization of rocky
exoplanets in the JWST and HWO era, and demonstrate how DAVINCI measurements will directly improve
exoplanet atmospheric modeling.
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All authors Stephen R. Kane, David S. Alexander, Shahid Aslam, Giada N. Arney, James B. Garvin, Stephanie A. Getty, Amy E. Hofmann, Noam R. Izenberg, Natasha M. Johnson, Erika Kohler, Emma L. Miles
Instrumentation and Methods for Astrophysics
Detectability-Aware Screening of Post-Merger Gravitational-Wave Damping Anomalies in Real Detector Noise: A Graph-Spectral Approach with Empirical Null Calibration
Ruslan Alaskarov
A two-stage methodological proof of concept for screening simplified post-merger gravitational-wave damping anomalies in real LIGO Livingston noise is presented. The injected signal is a controlled damped-sinusoid proxy rather than a physically complete binary-
neutron-
star post-merger waveform; it is used to test statistical detectability and damping-time scoring under real-noise calibration. Stage 1 constructs a local time-frequency graph from Constant-Q representations of whitened candidate windows and uses the leading
eigenvalue as a detectability statistic, with its null distribution calibrated empirically on real detector noise. Stage 2 estimates an effective damping-time score for Stage-1-passing candidates using nonlinear least squares and an interpretable ridge/energy-decay
estimator, with thresholds fixed before final held-out evaluation. The matched-filter SNR convention is checked with synthetic Gaussian noise, while the graph statistic is assessed through power-comparison and tile-shuffling tests. On a held-out real-noise test block, the nonlinear least-squares Stage-2 score gives AUC = 0.943 and TPR = 0.879 at FPR = 0.012, outperforming a calibrated power-only baseline.
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Instrumentation and Methods for Astrophysics
Agentic research is oxymoronic
Natalie B. Hogg
The use of agentic large
language models obviates human interpretation of scientific results, and will lead to substantial distrust in the literature.
Instrumentation and Methods for Astrophysics
Ad Astra White Paper: A Pitch for the Next 25 Years of NASA's Physics of the Cosmos Program
Eric Burns, Ivan Agullo, Igor Andreoni et al. (+7 more)
Astrophysical observations of our universe have been key to our understanding of how the universe works. Shortly after the turn of the millennium, the National Research Council delivered Connecting
Quarks with the Cosmos: Eleven Science Questions for the New Century. In the subsequent quarter-century, we have made substantial progress in answering each question. These advancements have, in part, arisen because of the success of major US facilities across several domains of physics, guided by long-term planning documents which still largely focus on these questions. This report seeks to provide a status update on each question, and to outline what space-based facilities are crucial for future progress, intended to guide NASA's preparatory work for the Astro2030 Decadal.
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All authors Eric Burns, Ivan Agullo, Igor Andreoni, Catherine M. Deibel, Christopher L. Fryer, Natasha Latouf, M. Coleman Miller, Jillian C. Rastinejad, Breann N. Sitarski, Zorawar Wadiasingh
Instrumentation and Methods for Astrophysics
Slysh haloes: the waste heat of cold computing as a submillimetre technosignature
Michael Garrett
Searches for Dysonian waste heat have operated almost exclusively in the mid-infrared and are therefore sensitive primarily to technology radiating at 100-600K. We argue that mature, computation-dominated civilisations may instead dissipate much of their energy at far lower temperatures. The Landauer cost of irreversible computation scales linearly with temperature, while ambient temperatures at large circumstellar radii approach the 2.7K
cosmic microwave background floor. Cold computation is therefore thermodynamically attractive and, because the required radiating area scales as T**-4, potentially conspicuous. These considerations predict a new object class, which we term the SLYSH
HALO after the first advocate of cold Dysonian searches. A Slysh
halo is a physically motivated partial Dyson swarm producing grey, line-free thermal emission from the cold outer regions of planetary systems. We show that such structures are energetically and materially plausible, and that M dwarfs provide especially favourable search targets. Archival far-infrared and submillimetre surveys of nearby
stars (DEBRIS, DUNES and SONS) can in principle be reinterpreted to constrain cold circumstellar dissipation at approximately the 10**20 Watt level, several orders of magnitude below the waste-heat luminosities targeted by previous infrared searches. Additional opportunities are provided by archival observations from Planck and the JCMT, together with the reprocessing of interferometric data from facilities such as ALMA and NOEMA. We assemble six observational discriminants that separate engineered radiators from natural cold sources and outline a three-tier search programme. Even a null result would provide the first temperature-complete assessment of Dysonian technosignatures.
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Instrumentation and Methods for Astrophysics
The Analysis, not the Aperture: End-to-End Transformer Reconstruction for Imaging Atmospheric Cherenkov Telescopes
Elli Jobst, Lea Heckmann, Lukas Heinrich et al. (+1 more)
Imaging Atmospheric Cherenkov
Telescopes (IACTs) detect very-high-energy gamma rays by imaging the nanosecond Cherenkov flash of the air shower they initiate in the Earth's atmosphere. For four decades the first steps of IACT event reconstruction have been essentially unchanged, relying on a heavy parameterisation and dimensionality reduction of the recorded images. This is reasonable when the image is bright, but discards important information when only a few tens of Cherenkov
photons are recorded, which is a primary reason why small
telescopes perform poorly at sub-TeV energies. We show that this limitation is a property of the analysis rather than of the hardware. We simulate a deliberately simple and idealised compact
telescope and treat each event as a short movie that is passed directly to a
video vision transformer with a factorised spatio-temporal encoder. A single composite network with a gradient-normalised multi-task loss performs gamma/
hadron classification, energy regression and arrival-direction regression at once. This is the first application of a
video vision transformer to IACT data. We compare it against an optimised standard analysis on the same
dataset. The
transformer lowers the energy threshold by a factor of three, from 0.22 to 0.07 TeV, and reconstructs arrival directions down to 0.05 TeV. At 0.2 TeV it increases the effective collection area by a factor of three, and raises the gamma/
hadron separation power from an area under the receiver operating characteristic curve of 0.80 to 0.91. At 0.05 TeV, where the standard analysis retains almost nothing, that area grows by nearly two orders of magnitude. These results show promising new opportunities for compact and affordable
telescopes operating at sub-TeV energies, paving the way for a broader exploration of time-domain astrophysics.
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All authors Elli Jobst, Lea Heckmann, Lukas Heinrich, David Paneque
Instrumentation and Methods for Astrophysics
Feasibility of Capillary-Driven Orbital Liquid Mirror Telescopes
Janoah Dietrich and Álvaro Romero-Calvo
Space-based
liquid mirror
telescopes (LMTs) have been recently proposed to overcome the scaling limits of traditional rigid mirrors. In these new space architectures, capillary forces would shape a reflective
liquid into a spherical optical surface in microgravity. However, the
equilibrium, stability, and dynamic behavior of such
liquid interfaces under orbital perturbations remain largely uncharacterized. This study investigates the feasibility of space LMTs by combining axisymmetric capillary with thin-film models. Solar radiation pressure and self-gravitation are found to be the dominant perturbations in Sun–Earth L2 orbits, causing
equilibrium deformations that exceed the $\lambda/20$ optical threshold at apertures above 0.86 m for visible ($\lambda = 380$ nm) and 1.58 m for near-infrared observatories ($\lambda = 2.5$ $\mu$m). Micrometeoroid impacts self-heal within seconds to minutes, settling after filling requires years to decades at large apertures, and propulsive maneuvers breach optical limits within seconds to hours. These results highlight the need for interface control in large-scale systems such as NASA's 50 m Fluidic
Telescope (FLUTE). Thermocapillary actuation supports apertures of 2.3/8.0 m (VIS/NIR) at 100 $\mu$K and 10.6/37.7 m at 10 $\mu$K. Simultaneously, parasitic Marangoni flows impose sub-mK uniformity for NIR and 1–100 $\mu$K for visible operation on any capillary LMT. Departing the capillary regime by imposing a surface-normal settling acceleration, ranging from 39 mm s$^{-2}$ (NIR,5 m) to 17 m s$^{-2}$ (VIS,50 m), is the most promising route to tens of meters in aperture. This approach enables a passive implementation effectively suppressing perturbation induced interface distortions and thermal Marangoni flows. Keywords:
Liquid mirror
telescope, Optics, Space
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Instrumentation and Methods for Astrophysics
The Auger Radio Infill SKALA Extension (ARISE): Science Case and Instrumentation (ARENA 2026)
Frank G. Schröder for the Pierre Auger Collaboration
The Auger
Radio Infill SKALA Extension (ARISE) at the Pierre Auger Observatory in Argentina was deployed in 2025 and measures
cosmic-ray air showers in the energy region of the Galactic-to-extragalactic transition. ARISE is comprised of 18 SKALA-2
antennas featuring two polarization channels each, deployed within $100\,$m of a surface detector station in the enhancement area of the Pierre Auger Observatory. This area of the surface array features a denser spacing of $433\,$m between surface stations, each equipped with underground
muon detectors. One of these surface detector stations provides a trigger for simultaneous readout of all ARISE
antenna channels. The wide frequency range of ARISE, from $50$ to $350\,$MHz, includes the sub-band of optimum signal-to-noise ratio for air-shower
radio emission against the Galactic
radio background. In combination with the dense
antenna spacing, this enables a relatively low detection threshold, and ARISE aims at demonstrating full detection efficiency for near-vertical air showers above $100\,$ PeV. As an advantage over the current
radio detectors at Auger, which are more efficient for inclined air showers, this would enable low systematic uncertainties for physics analysis combining ARISE
radio measurements with coincident measurements of the underground
muon detectors in the same area. In this presentation, we will provide an overview over the ARISE instrumentation operating at the Pierre Auger Observatory and will outline the science goals.
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Instrumentation and Methods for Astrophysics · Cross-listed from astro-ph.HE
The First Array-Wide Diffuse Flux Search for UHE Neutrinos with the Askaryan Radio Array
Alan Salcedo-Gomez, Marco Stein Muzio and for the ARA Collaboration
The Askaryan
Radio Array (ARA) is an ultrahigh energy (UHE)
neutrino detector at the South Pole that searches for impulsive broadband
radio signals from
neutrino-induced particle showers in glacial ice. ARA consists of five autonomous stations with receiving
antennas deployed up to 200 m deep and has accumulated the largest livetime of any in-ice
radio array. We present the first array-wide diffuse UHE
neutrino search using data collected from January 2013 to December 2023, incorporating improved detector characterization and simulation, including data-driven noise and electronics models, revised
antenna responses, and updated
neutrino interaction and lepton propagation modeling, within a unified framework for event processing, background rejection, and cut optimization across independently operating stations. This search is expected either to identify the first UHE
neutrino candidates observed by an in-ice
radio detector or to set the most stringent UHE
neutrino diffuse flux limits above a few EeV, while informing analysis strategies for under-construction and future
radio arrays, such as RNO-G and IceCube-Gen2
Radio.
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Instrumentation and Methods for Astrophysics
METIS high-contrast imaging simulations: From instrument modelling to science readiness
Gilles Orban de Xivry, Olivier Absil, Iain Hammond et al. (+9 more)
The Mid-infrared Extremely Large
Telescope (ELT) Imager and Spectrograph (METIS) instrument, expected to see first light in early 2030, aims to detect and characterise
exoplanets and circumstellar disks through high- contrast imaging (HCI) and spectroscopy. The High-contrast End-to-End Performance Simulator (HEEPS), initially developed to support the design of the METIS HCI modes, has evolved into a crucial tool for the METIS science team to prepare and optimize observations. HEEPS is an open-source Python-based software with a modular architecture, integrating the wavefront Fresnel propagation package PROPER, and HCI image processing with the
Vortex Image Processing (VIP) package. Though designed for METIS, its modularity has been applied to other HCI instruments as well. This work presents recent updates to HEEPS, including modelling of the final METIS pupil and Lyot stops, revised quasi-static non-common path aberrations (NCPA) and Talbot effect simulations informed by as-built optical surface errors, and updated METIS Single Conjugated Adaptive Optics (SCAO) simulations. We also discuss advancements in NCPA control strategies focusing on framerate, latency and sensing performance optimization, particularly for mitigating water vapor seeing effects using the asymmetric Lyot wavefront sensor (ALF)
algorithm. With these refinements, we present a comprehensive grid of HCI performance simulations for METIS, covering a range of magnitudes in the L, M, and N-bands, and several HCI observing modes. These simulations produce updated 5-sigma sensitivity contrast curves and mock HCI observations, providing key insights on HCI performance for instrument optimization and science observation planning. Our results underscore the key role of end-to-end simulations in bridging instrumental design and scientific readiness in the ELT era.
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All authors Gilles Orban de Xivry, Olivier Absil, Iain Hammond, Thomas Bertram, Roy van Boekel, André Boné, Gaël Chauvin, Valentin Christiaens, Denis Dolkens, Gilles Otten, Prashant Pathak, Nuño Pereira
Instrumentation and Methods for Astrophysics · Cross-listed from astro-ph.HE
The DSA/Chronoscope fast radio burst survey: forecasts and science overview
Liam Connor, Kaitlyn Shin, Vikram Ravi et al. (+14 more)
Fast
radio bursts (FRBs) are bright extragalactic transients with several mysteries surrounding their origins. Large FRB samples enable accurate measurements of the
cosmic matter distribution, in particular on scales $\lesssim 10$ Mpc. These measurements will impact cosmological inference and our understanding of astrophysical feedback, from the circumgalactic medium to cluster scales. Here we forecast the expected yields,
redshifts, and host
galaxies of FRBs as observed by the Deep Synoptic Array (DSA), and describe the key science cases enabled by the large FRB sample. The DSA will be an interferometer consisting of 1650$\times$6.15 m
antennas, operating between 0.7–2 GHz, to be located in Nevada, USA. The Chronoscope backend on the DSA, hereafter DSA/Chronoscope, is designed to search for FRBs across the field of view in real time, enabling the storage of full-polarization voltage data. Extrapolating from existing FRB surveys, we expect roughly $10^4$ FRB detections per year in each of three search sub-bands. Combining across sub-bands, the survey could produce $\sim$ 10$^5$ FRBs over the nominal 5-year DSA survey, assuming Euclidean source counts and a baseline compute backend that can search $6\times10^6$ beams at 1 ms sampling. The well-characterized DSA synthesized beam and deep simultaneous reference images will enable localization precisions of $\lesssim$ 250 milliarcseconds. Key science cases include the use of FRB propagation effects in probing
cosmic baryons, and studies of the FRB phenomenon using FRB host
galaxies and their local environment, as well as multiwavelength counterparts.
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All authors Liam Connor, Kaitlyn Shin, Vikram Ravi, Stella Koch Ocker, Casey J. Law, Kritti Sharma, Samuel McCarty, Gregg Hallinan, Shami Chatterjee, James M. Cordes, Dean Howarth, Fabian Walter, Elisabeth Krause, Vishnu Balakrishnan, Alexa C. Gordon, Calvin Leung, Shion Andrew
Instrumentation and Methods for Astrophysics
Beyond $X_\mathrm{max}$ : Reconstructing Air Shower Profiles with Information Field Theory with SKA-Low
Keito Watanabe, Tim Huege, Torsten Enßlin et al. (+33 more)
While
radio measurements of extensive air showers have shown to achieve a high precision of $X_\mathrm{max}$ sensitivity, it has been shown that parameters beyond $X_\mathrm{max}$ can also be reconstructed. These shape parameters contain additional sensitivity to the hadronic physics in the shower as well as its mass composition. In this work, we showcase a reconstruction framework to recover the full longitudinal profile from realistic
radio measurements. The framework is based on Information Field Theory that infers the full profile with a forward-based model, which uses a Gaisser-Hillas profile with weakly informative shower priors, SMIET with a template library to synthesise pulses at any event geometry, and a realistic
antenna response and noise level emulating that of SKA-Low. We verify the self-consistency of our framework with $\sim 900$ events generated with SMIET with
antennas placed on the $\vec{v} \times (\vec{v} \times \vec{B})$ axis. The framework recovers the full profile within uncertainty and capture correlations between shower parameters. We yield an $X_\mathrm{max}$ resolution of $< 9$ g cm$^{-2}$ as well as resolutions of the width and asymmetry with minimal bias. The profile is also recovered with a bias of $< 4$% at all atmospheric depths $< 1200$ g cm$^{-2}$. We aim to apply this framework with pulses simulated from CoREAS with measured noise, ultimately extending the framework to realistic
antenna layouts such as from LOFAR or SKA-Low.
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All authors Keito Watanabe, Tim Huege, Torsten Enßlin, Vincent Eberle, Sjoerd Bouma, Justin Bray, Stijn Buitink, Arthur Corstanje, Vital De Henau, Edwin Dickinson, Tjibbe Gottmer, Brian Hare, Haoning He, Jörg Hörandel, 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, Marc Waterson, Chao Zhang, Pengfei Zhang, Yi Zhang
Instrumentation and Methods for Astrophysics · Cross-listed from astro-ph.SR
Extremes of solar spectral irradiance in the SORCE/XPS record
Enzo Brasil, Cira E. G. Otiniano, Carolyne Brito et al. (+2 more)
Extreme and rare changes in space mission solar irradiance records are scientifically relevant but difficult to quantify because these records are finite, instrument dependent, and affected by observational gaps and time varying measurement quality. We evaluated extreme daily logarithmic changes in the band integrated 0.1-7.0 nm irradiance measured by photodiode 7 of the Solar Radiation and
Climate Experiment/X-Ray Photometer System (SORCE/XPS) from 2005 to 2019. After constructing a regular daily series by linear interpolation, we analyzed daily logarithmic changes in irradiance and fitted stationary Generalized Extreme Value models to 60 day block maxima and transformed 15 day block minima. Block lengths were selected using Ljung-Box diagnostics and sample autocorrelation functions. Maximum likelihood estimation was used as the primary inferential method, with probability weighted moments as a sensitivity check. The maximum likelihood GEV shape estimates were 0.1661 for maxima and 0.2928 for transformed minima, with closely aligned estimates under the two fitting methods. These positive point estimates are compatible with Fréchet type tails under the selected block constructions. Annualized return levels provide interpretable summaries of extreme relative increases and reductions, but estimates for long return periods remain strongly dependent on extrapolation beyond the 15 year record. Reported measurement precision and absolute uncertainty were used to qualify the interpretation of the fitted tails and were not propagated through the likelihood. By combining EVT based tail modeling with explicit consideration of measurement precision, absolute uncertainty, interpolation, and mission data gaps, the analysis provides an uncertainty aware astrostatistical baseline for extreme value inference from processed solar mission records.
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All authors Enzo Brasil, Cira E. G. Otiniano, Carolyne Brito, Beatriz Albernaz, Fidel Morales
Instrumentation and Methods for Astrophysics
Radio measurements of air showers with the IceCube-Gen2 surface prototype station at the Pierre Auger Observatory
Stef Verpoest, for the IceCube-Gen2 Collaboration and for the Pierre Auger Collaboration
The design of the IceCube-Gen2 observatory, proposed as a next-generation extension of IceCube, includes a surface array consisting of scintillators and
radio antennas. In addition to several such detectors already deployed at IceCube's surface array at the South Pole, a complete prototype station including three SKALA
antennas has been operating at the Pierre Auger Observatory for several years. This setup has been used to successfully observe
radio signals from air showers, demonstrated through coincident observations with the Auger Surface Detector. In this contribution, we present an updated analysis of these
radio signals, and compare them to CoREAS simulations using the reconstruction from the Auger Surface Detector as input.
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Instrumentation and Methods for Astrophysics
On-sky demonstration of a vector Zernike wavefront sensor in a cascaded adaptive optics system
M. Motte, V. Chambouleyron, R. Fétick et al. (+13 more)
To directly image and characterise Earth-like
exoplanets, future high-contrast instruments will require adaptive-optics systems operating at increasingly high loop frequencies to reduce temporal errors. Increasing the loop frequency reduces the signal-to-noise ratio per wavefront-sensor frame, making highly sensitive wavefront sensors, such as the Zernike wavefront sensor (ZWFS), attractive candidates. However, the limited dynamic range of the classical ZWFS makes on-sky operation challenging. We therefore investigate whether a ZWFS can be used as a second-stage sensor in an on-sky cascaded adaptive-optics system. To this end, we added a second AO stage, called OZIRIIS, to the PAPYRUS platform at the Observatoire de Haute-Provence. OZIRIIS combines a vector Zernike wavefront sensor (v-ZWFS) with a 97-actuator deformable mirror operating at 400 Hz downstream of the pyramid-based first AO stage. Real-time control relied on a single ZWFS signal, while the full v-ZWFS was used a posteriori for non-linear reconstruction and telemetry analysis. The second-stage correction increased the measured Strehl ratio by up to 16 percentage points. Analysis of the telemetry using the full v-ZWFS to reconstruct residuals revealed optical-gain effects affecting the ZWFS at low Strehl ratio. The good agreement between on-sky measurements and numerical simulations further supports the calibration strategy based on synthetic reference signals and interaction
matrices. These results demonstrate that Zernike wavefront sensing can be operated in closed loop on sky and support its use in future cascaded extreme adaptive-optics systems.
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All authors M. Motte, V. Chambouleyron, R. Fétick, F. Oyarzun, M. A. Alagao, A. Striffling, E. Vinerskas, J.-F. Sauvage, C. T. Héritier, E. Muslimov, M. Cissé, A. Rahim, J. Kent Wallace, T. Wenger, B. Neichel, T. Fusco
Instrumentation and Methods for Astrophysics
Learning Radio Astronomical Representations with LeJEPA and Very Small Models
Erica Lastufka, Mariia Drozdova, Vitaliy Kinakh et al. (+4 more)
Representations learned by
vision foundation models pretrained on natural images have been shown to be useful for out-of-domain astronomical images. Performance on scientific downstream tasks increases with model size, which both carries higher inference costs and limits scalability, even when considering parameter-efficient adaptation. An alternative is to learn representations directly from astronomical observations rather than natural images, through self-supervised pretraining. We evaluate LeJEPA's ability to learn robust representations using very small
vision models ($\sim$6M parameters) pretrained on
Radio Galaxy Zoo images, comparing with established self-supervised frameworks. We test whether LeJEPA's latent-space regularization leads to better
radio galaxy morphology classification. Across three evaluation
datasets, LeJEPA achieves performance comparable to a substantially larger foundation model while producing more consistent representations across training and evaluation
datasets. These results suggest that the choice of representation learning objective is critical for enabling small domain-specific models to achieve performance competitive with representations transferred from large foundation models in scientific imaging.
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All authors Erica Lastufka, Mariia Drozdova, Vitaliy Kinakh, Taras Holotyak, Miroslava Dessuages-Zavadsky, Daniel Schaerer, Svyatoslav Voloshynovskiy
Instrumentation and Methods for Astrophysics · Cross-listed from nucl-th
NS-UNO: Neutron Star EoS Inference from an Unconstrained Number of Observations
Valéria Carvalho, Márcio Ferreira, Michał Bejger et al. (+1 more)
Future multimessenger observations of
neutron stars (NS) are expected to substantially increase both the number and precision of astrophysical constraints on the equation of state (EoS) of dense matter. This motivates inference frameworks capable of accommodating a variable, non fixed number of observations while preserving the posterior information associated with each measurement. In this work, we introduce NS-UNO, a Neural Posterior Estimation framework for NS EoS inference designed to accommodate an Unconstrained Number of Observations (UNO). NS-UNO combines a hierarchical DeepSets model with a conditional normalising flow, enabling a single trained model to perform inference from mass-radius observation sets of varying size, with each observation represented by a set of posterior samples. We demonstrate accurate and well calibrated posterior reconstructions using a model trained jointly on piecewise polytropic and non-parametric Gaussian process EoS ensembles. The reconstruction improves as observations probe a broader range of NS masses, while remaining robust to variations in the number and precision of the observations. The model also generalises to EoSs outside the families used during training. Finally, we qualitatively demonstrate the framework on current multimessenger constraints from NICER and GW170817. NS-UNO provides a flexible and scalable approach to NS EoS inference, naturally suited to the increasingly diverse observational
datasets expected from next generation multimessenger astronomy.
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All authors Valéria Carvalho, Márcio Ferreira, Michał Bejger, Constança Providência