Instrumentation and Methods for Astrophysics · Cross-listed from physics.ins-det
Cryogenic Mechanical Loss of GaAs/AlGaAs Crystalline Coatings
Nicholas A. Didio, Steven D. Penn, Satoshi Tanioka et al. (+3 more)
Optical coatings with minimal thermal noise are essential for high-precision,
laser-based metrology experiments. Substrate-transferred crystalline GaAs/Al$_{0.92}$Ga$_{0.08}$As coatings have the lowest thermal noise for high-reflectivity mirror coatings with $\lambda =900$ nm – 12 $\mu$m. Time-frequency stabilization experiments have demonstrated that GaAs/AlGaAs mirror coatings have a lower noise floor than amorphous mirror coatings. These mirrors are now being developed at sizes $\ge 300$ mm for gravitational-wave detectors. In order to understand the coating's fundamental loss mechanisms, which cause thermal noise, we have performed the first measurement of the mechanical loss at cryogenic temperatures using a cryogenic,
multimodal, gentle nodal suspension system, which operates from 12 K to room temperature. This initial measurement used a silicon substrate whose asymmetry produced excess friction with the nodal support. Accounting for this friction and Akhiezer loss in the substrate and coating, the mechanical loss agrees well with the thermal noise observed in experiments using cryogenic fixed-cavities with GaAs/AlGaAs mirrors.
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All authors Nicholas A. Didio, Steven D. Penn, Satoshi Tanioka, Elenna M. Capote, Garrett D. Cole, Stefan W. Ballmer
Instrumentation and Methods for Astrophysics · Cross-listed from gr-qc
A fast, differentiable neural-network surrogate for precessing binary black-hole waveforms
Beka Modrekiladze
Gravitational-wave parameter estimation requires millions of waveform evaluations per event, a cost that constrains real-time inference and population studies. We present a fast, fully differentiable neural-network surrogate for the precessing numerical-relativity model \NRSur{}, spanning its full intrinsic parameter space $\lambda=(q,\,\boldsymbol{\chi}_1,\,\boldsymbol{\chi}_2)$ together with the reference orbital frequency $\omega_0$. Rather than a single polarization at a fixed orientation, the surrogate predicts the inertial-frame spherical-harmonic modes $h_{\ell m}$ ($\ell\leq 4$), so that both polarizations $h_+,h_\times$ at an arbitrary orientation $(\iota,\varphi,\psi)$ are reconstructed from one network evaluation through an analytic, differentiable mode-to-strain projection. Trained on $6\times10^5$ waveforms, it attains a fixed-orientation match of mean $0.975$ (median $0.988$) and an orientation-averaged match of mean $0.940$ (median $0.975$) for $q\in[1,4]$, $|\boldsymbol{\chi}_{1,2}|\leq 0.8$, while keeping the overall strain amplitude physical (median ratio $0.98$). It generates a waveform in $\SI{12}{ms}$ (single) and ${\sim}3.5\times10^4$ per second in batches on a single GPU. Because the mode-to-strain projection is analytic, the surrogate is differentiable in both intrinsic and extrinsic parameters, yielding a full 13-dimensional Fisher
matrix (validated against finite differences) and gradient-based (HMC/NUTS) parameter estimation.
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Instrumentation and Methods for Astrophysics
The Space Coronagraph Optical Bench (SCoOB): 11. Modeling and correction of chromatic aberrations
Kyle Van Gorkom, Ramya M. Anche, Saraswathi Kalyani Subramanian et al. (+12 more)
The space coronagraph optical bench (SCoOB) is a high contrast imaging testbed designed to demonstrate starlight suppression techniques at visible wavelengths in a space-like
vacuum environment. Since the previous proceedings, the testbed has undergone major component upgrades, including a 100%-yield BMC Kilo-C deformable mirror, a black silicon pupil stop, and circular polarizers between wedged substrates. To assess the performance limits imposed by lateral chromatic aberration induced by refractive optical elements, we develop analytic and numerical tools to predict the broadband contrast. Additionally, we present the broadband contrast performance of the testbed using implicit electric field conjugation with multiple sensing bands for broadband control.
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All authors Kyle Van Gorkom, Ramya M. Anche, Saraswathi Kalyani Subramanian, William Melby, Kian Milani, Emory Jenkins, Irina Stefan, Adam Schilperoort, Patrick Ingraham, Jaren N. Ashcraft, Kevin Derby, Daewook Kim, Heejoo Choi, Olivier Durney, Ewan S. Douglas
Instrumentation and Methods for Astrophysics
The Space Coronagraph Optical Bench (SCoOB): X. Dark zone maintenance
Saraswathi Kalyani Subramanian, Kyle Van Gorkom, Ramya Anche et al. (+12 more)
The Space Coronagraph Optical Bench (SCoOB) is a
vacuum high contrast imaging testbed designed to demonstrate starlight suppression at optical wavelengths and obtain contrasts better than 10$^{-8}$ in a one-sided dark hole from 3 to 10 $\lambda/D$ using a vector
vortex coronagraph (VVC) mask. Some of the recent efforts have been in testing dark zone maintenance (DZM)
algorithms which are used to stabilize the contrast in the presence of wavefront drifts and allow for the long integration times required by
exoplanet observations. In this work, we discuss the results from simulations with two DZM
algorithms - linear dark field control (LDFC) and extended Kalman Filter-based (EKF) DZM. We also report preliminary results from the testbed with LDFC.
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All authors Saraswathi Kalyani Subramanian, Kyle Van Gorkom, Ramya Anche, William Melby, Kian Milani, Emory Jenkins, Irina Stefan, Adam Schilperoort, Jaren N. Ashcraft, Heejoo Choi, Kevin Derby, Olivier Durney, Daewook Kim, Kelsey Miller, Ewan S. Douglas
Instrumentation and Methods for Astrophysics
Fast, low noise, megapixel detector and readout systems for future X-ray astronomy missions
Sven Herrmann, Peter Orel, Tanmoy Chattopadhyay et al. (+22 more)
Next-generation strategic X-ray astronomy missions will require the simultaneous achievement of high angular resolution, large effective collecting area, and wide-field imaging with large-format focal plane detectors. Realizing the associated science objectives–ranging from precision measurements of bright point sources to the detection and characterization of faint diffuse emission-places stringent and, in some cases, competing requirements on detector performance. In particular, high frame rates are necessary to mitigate
photon pile-up in observations of bright sources and to reduce contamination from particle-induced background in measurements of low surface brightness structures. At the same time, these instruments must preserve excellent soft X-ray response, which places tight constraints on read noise and on the fidelity of event characterization. State-of-the-art X-ray charge-coupled devices (CCDs) approach many of the key performance metrics required for these missions, but readout speed remains a primary limitation. Addressing this gap requires readout architectures that scale to high channel count, sustain high pixel throughput, and preserve the low-noise characteristics needed for soft X-ray sensitivity.
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All authors Sven Herrmann, Peter Orel, Tanmoy Chattopadhyay, Haley R. Stueber, Jill Juneau, Abigail Y. Pan, Kevan Donlon, Declan O'Neill, Gregory Prigozhin, Eric D. Miller, R. Glenn Morris, Tonya L. Peshel, Artem Poliszczuk, Beverly LaMarr, Catherine E. Grant, Christopher Leitz, Steven W. Allen, Sebastian Albrecht, Marshall W. Bautz, Michael Cooper, Ajay Dakshinamurthy, Matthew Heine, Anna Schweingruber, Keith Warner, Daniel Wilkins
Instrumentation and Methods for Astrophysics
A new NASA Pioneer: the Globe Orbiting Soft X-ray Polarimeter (GOSoX)
Herman L Marshall, Sarah N T Heine, Alan Garner et al. (+16 more)
The Globe Orbiting Soft X-ray Polarimeter (GOSoX) is a spectropolarimeter for the soft X-ray band. GOSoX is based on the Rocket Experiment Demonstration of a Soft X-ray Polarimeter (REDSoX), a NASA-funded sounding rocket payload. Like REDSoX, GOSoX consists of Wolter I X-ray optics from NASA/MSFC, critical-angle transmission (CAT) gratings made at MIT, and multilayer (ML) coated mirrors from LBNL that polarize the X-rays. Colleagues at U. Tübingen will adapt commercially available sCMOS sensors for the focal plane. The grating dispersion is matched to the lateral grading of ML mirrors set at 45\deg. GOSoX can measure polarization across the entire 0.2-0.4 keV band with a spectral resolution E/dE $\sim$100. Minimum detectable polarizations (MDPs) of 3-10% are expected for over a dozen targets in a one-year mission. The mission was selected by NASA for launch in 2030.
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All authors Herman L Marshall, Sarah N T Heine, Alan Garner, Sean Gunderson, Hans M Guenther, Ralf K Heilmann, Stephen Bongiorno, Eric M Gullikson, Andrea Santangelo, Chris Tenzer, Ruth Kelly, Silvia Zane, Roberto Taverna, Roberto Turolla, Michela Negro, Rozenn Boissay-Malaquin, Luigi Gallo, Honghui Liu, Swati Ravi
Instrumentation and Methods for Astrophysics
Single-Photon Counting CMOS Detectors for the Habitable Worlds Observatory
Edwin Alexani, Justin P. Gallagher and Donald F. Figer
The Habitable Worlds Observatory (HWO) is NASA's current New Great Observatory concept. HWO will observe the universe to search for life beyond Earth. It will need unprecedented instrument stability and detector performance. However, no single detector technology currently satisfies HWO's demanding specifications. Complementary metal-oxide-
semiconductor (CMOS) single-
photon counting detectors (SPCDs) are excellent candidates for further development, as they already satisfy several specifications for HWO. We report the results of a characterization program for 9.4 Mpixel CMOS SPCDs. We measure a dark current of 0.0005 e-/s/pixel, a read noise of 0.19 e-/pixel, a peak
quantum efficiency of 88% at 485 nm, negligible crosstalk and persistence, and we present conversion gain measurements. The detector satisfies several key HWO performance requirements, including deep sub-electron read noise and low dark current, while additional development is required in ultraviolet
quantum efficiency and full mission qualification. We include a simulated low-flux observation using characterization results, along with a roadmap for developing CMOS SPCDs to satisfy HWO specifications, especially at UV wavelengths.
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Instrumentation and Methods for Astrophysics · Cross-listed from physics.hist-ph
The orientation of historic churches in Las Palmas de Gran Canaria and its surroundings: preliminary results
Alejandro Gangui, Jose Ricra, Joaquin Pallares et al. (+1 more)
We present preliminary results of the analysis of the precise spatial orientation of colonial Christian churches located in the city of Las Palmas, capital of the island of Gran Canaria (Spain), and its surroundings. Our sample consists of 27 churches, 15 of which belong to the city proper while the rest are situated within roughly 12 km away inland. Most of these churches were constructed between the first decades after the Castilian conquest of the island, and the end of the 19th century. In our analysis we examine whether these orientations respond to calendrical coincidences, to the main features of the landscape, or whether the standard tradition was followed regarding the orientation of the churches' apses eastwards. We find that no church in the sample is oriented towards points of the horizon on which the Sun rises on the day of the patronal feasts. Furthermore, we find no correlation between the global orientation pattern and the orography of the island which, near the local prominent Guiniguada ravine, could have been an important factor at the time of the construction of the churches. What we do find is that most of the orientations fit within the solar range, mainly to the east but also with a few historic churches oriented towards the west, while less than 20% have astronomical declinations outside of this range. In the statistical analysis, the declination histogram for the sample shows a pattern where the apses of the churches point consistently to the north of due east. This might signal constructions that were oriented to the rising Sun on dates close to Easter. We briefly discuss the implications these findings may have for a future study of the rest of Gran Canaria, which includes several dozens of historic churches scattered throughout the valleys, slopes, and volcanic calderas of the island.
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All authors Alejandro Gangui, Jose Ricra, Joaquin Pallares, Juan Antonio Belmonte
Instrumentation and Methods for Astrophysics · Cross-listed from astro-ph.SR
The Bimodal Mass Ratio Distribution of the Hyades
Henri M.J. Boffin
The distribution of stellar mass ratios, q, in binary systems provides critical insights into the dynamical history and
star-formation processes of open clusters. Here, I re-evaluate the recently published mass ratio distribution (MRD) of a sample of spectroscopic binaries in the Hyades cluster, which was based on stellar positions in colour-magnitude diagrams. I demonstrate that the mass ratios derived in that work are statistically inconsistent with a random distribution of orbital inclinations. Furthermore, several systems yielded non-physical results. By applying a Richardson-Lucy deconvolution to the spectroscopic mass functions and assuming a random distribution of inclinations, I re-derive the MRD for this sample, showing that it is statistically different from a uniform distribution. I further find a significant dependence on the primary mass: systems with lower-mass primaries exhibit a peak near q~1, whereas more massive primaries show a distribution heavily skewed toward low mass ratios (q~0.15). These findings highlight the potential pitfalls of photometric mass ratio derivations and underscore the need for further verification with future data releases such as Gaia DR4.
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Instrumentation and Methods for Astrophysics · Cross-listed from astro-ph.EP
Rings in the Sky: Orbital Data Centres and Potential Impacts to Astronomy and the Sky
Aaron C. Boley, Samantha M. Lawler and Hanno Rein
Megaconstellations of orbital data centres (ODCs) have the potential to fundamentally change the sky without a concerted mitigation effort. Potential changes include producing large coherent structures that would be visible during twilight and some portions of the night, as well as produce persistent infrared and
radio source regions. We investigate the potential sky impacts of three ODC designs, as proposed by three companies. While more companies have proposed to launch megaconstellations of ODCs, other potential operators are expected to use the same design principles as presented here. These systems would produce large ring structures with each ring passing through the sky twice a day. The largest impacts are expected to occur during winter, where ring structures could be seen sweeping through otherwise dark skies. The confinement of the rings' orbital nodes will play a large role in determining whether the rings will be dense arcs in the sky or will produce sky-wide interference. The rings will persist throughout the day in polar regions, with the potential to interfere with polar science initiatives. Such structures will further have societal implications for high-latitude communities. We use simplified brightness models, which compare well with more detailed calculations, to show that brightness mitigation and/or hard limits on satellite numbers will be essential for preventing a future that has more visible satellites in the sky than visible
stars during certain times of night.
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Instrumentation and Methods for Astrophysics · Cross-listed from astro-ph.GA
Molecular absorption lines toward the Galactic ISM detected at 89 GHz with VLBI
Keisuke Nakashima, Hiroshi Imai and Youngjoo Yun
As the first step to explore the Galactic foreground interstellar medium (ISM) with high angular resolution, we investigated the detectability of molecular absorption lines with very long baseline interferometry (VLBI). This paper reports our first observations of HCO+ J=1-0 and HCN J=1-0 molecular absorption lines toward four extragalactic compact
radio sources with the Korean VLBI Network (KVN). HCO+ absorption lines were detected in all directions and HCN absorption lines in three directions. All of these detections, except for two HCO+ detections, are reported here for the first time with VLBI. We find that the column density ratio N(HCN)/N(HCO+) obtained with VLBI is consistent with the trend established from observations with connected-element interferometers, demonstrating the feasibility of future VLBI studies of molecular absorption.
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Instrumentation and Methods for Astrophysics
Enhancing the sensitivity of next-generation X-ray imaging detectors with artificial intelligence and advanced event reconstruction algorithms
D. R. Wilkins, A. Poliszczuk, A. Y. Pan et al. (+11 more)
Advanced
algorithms incorporating artificial intelligence and machine learning (AI/ML) enhance the sensitivity of X-ray imaging detectors and the scientific capabilities of future X-ray missions. In orbit, current instruments are limited in their sensitivity by (1) the instrumental background, induced by
cosmic rays which produce signals that can be confused for genuine, astrophysical X-rays, and (2) the ability to reconstruct the detected
photon events, degrading the
quantum efficiency and energy resolution at the lowest energies, where much discovery space resides. We report on the development of prototype
algorithms designed to operate on the raw frame-level data to provide improved identification of particle-induced background events and enhanced energy reconstruction. These
algorithms consider the contextual information from all signals in a frame, and are built upon physics-motivated models of charge
diffusion and signal generation within the detector. Using high fidelity simulations, we show that following recent developments, prototype ML
algorithms can reduce the unrejected particle background by up to 68 per cent compared with traditional filtering methods when operated in an aggressive mode suitable for source detection in imaging surveys, or up to 40 per cent in a conservative mode designed to prioritize accurate measurements of the spectrum. We find that next-generation event reconstruction
algorithms improve the sensitivity and energy resolution of CCD-like detectors at event energies below 1keV, and can aid in background filtering, and reduce the impact of
photon pile-up. We present new laboratory data that demonstrates the performance of the
algorithm on the MIT-LL CCID-93 CCD detector. Together with the capabilities of next-generation high-speed, low-noise detectors, these
algorithms can satisfy the requirements for future X-ray flagship missions.
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All authors D. R. Wilkins, A. Poliszczuk, A. Y. Pan, L. Sajkov, S. W. Allen, M. Heine, C. E. Grant, M. W. Bautz, T. Chattopadhyay, K. Donlon, S. Herrmann, B. LaMarr, E. D. Miller, P. Orel
Instrumentation and Methods for Astrophysics
The Research Impact of the Jodrell Bank Observatory and Other Facilities affected by the UK Science Funding Cuts in 2025
Rommulus Francis Lewis, Amruth Alfred and Hetansh Shah
The United Kingdom Research and Innovation body and the Science and Technology Facilities Council recently announced funding cuts to facilities at the Jodrell Bank Observatory, specifically the e-MERLIN network of
radio telescopes as well as a few other facilities across the world like the James Clerk Maxwell
Telescope. These funding cuts have been extremely disturbing to the Astronomical community, as is evident from widespread news coverage about these cuts. Here we present a short analysis of the research impact e-MERLIN and the other affected facilities had in 2025 from a
dataset consisting of every Astrophysics paper submitted to the arXiv during the year. This serves to help members of the community and all stakeholders make better sense of the research output of the facilities that are not being prioritised under the new budget.
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Instrumentation and Methods for Astrophysics
SDSS-V Local Volume Mapper (LVM): Dithered Data Cube Reconstruction with 3dcubegen
H. J. Ibarra-Medel, A. Z. Lugo-Aranda, R. de J. Zermeño et al. (+16 more)
The Sloan Digital Sky Survey V (SDSS-V) Local Volume Mapper (LVM) is conducting an unprecedented wide-field integral field spectroscopic survey of the Milky Way, the Magellanic Clouds, and nearby
galaxies using a strategy based on multiple dithered observations to achieve full spatial coverage, improved spatial sampling, and enhanced spectral depth. However, the scientific exploitation of these observations requires a robust methodology to combine the individual row-stacked spectra (RSS) into homogeneous three-dimensional data cubes. In this work, we present 3DCubeGen, a flexible and scalable reconstruction tool designed to combine multiple LVM dithers while preserving flux and propagating uncertainties. The method enables the coaddition of large
datasets, improving the signal-to-noise ratio, enhancing spatial resolution, and increasing sensitivity to faint emission features, following and extending approaches previously implemented in integral field surveys such as CALIFA. We apply 3DCubeGen to a large set of LVM observations, including the Large and Small Magellanic Clouds and nearby
galaxies, combining thousands of dithers corresponding to millions of spectra. The resulting data products demonstrate significant improvements in spatial sampling and spectral depth, enabling detailed studies of the ionised gas, stellar populations, and kinematics across extended regions. 3DCubeGen provides a robust and scalable solution for LVM data cube reconstruction and represents a key tool for exploiting the scientific potential of the SDSS-V Local Volume Mapper.
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All authors H. J. Ibarra-Medel, A. Z. Lugo-Aranda, R. de J. Zermeño, Sebastián F. Sánchez, Lesly Castañeda-Carlos, J. Eduardo Méndez-Delgado, K. Kreckel, Roeland P. van der Marel, R. Orozco-Duarte, Aida Wofford, Castalia Alenka Negrete, Irene Cruz-González, Carlos G. Román-Zúñiga, Guillermo A. Blanc, Evelyn J. Johnston, Ivan Katkov, Alfredo J. Mejía-Narváez, Tony Wong, Oleg V. Egorov
Instrumentation and Methods for Astrophysics · Cross-listed from astro-ph.HE
Generation of Correlated Time Series for X-ray Astronomy Applications
Seth Rowan Larner, Michael A. Nowak and Jörn Wilms
Cross-spectral methods have become essential for studying
accretion physics in X-ray binaries and active galactic
nuclei, where coherence and phase lag measurements constrain physical models and reveal variability components invisible in power spectra alone. Recent multi-Lorentzian fitting techniques have uncovered new quasi-periodic features through joint analysis of power spectra and cross-spectra, but testing these methods requires synthetic data with realistic statistical properties. We present an
algorithm for generating pairs of time series with arbitrary power spectra, coherence functions, and phase lag profiles. The method extends existing methods by decomposing the dependent time series into coherent and incoherent components, where the coherent part is constructed through a complex transfer function applied to a reference series. We derive the transfer function and normalization required to preserve target spectral shapes while achieving specified cross-spectral properties. We obtain approximate analytic expressions for the variance of coherence and phase lag
estimators and construct the approximate covariance
matrix relating these quantities to the underlying power and cross-spectra. When fitting models jointly to power and cross-spectra, these correlations must be incorporated into the likelihood. We apply the method to a two-Lorentzian model with component-specific phase lags and demonstrate close agreement between input models and generated power spectra, coherence function, and phase lag profile across four decades in frequency.
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Instrumentation and Methods for Astrophysics
CCAT: Optical Design of the 410 GHz Prime-Cam Module
Tilak M. Patel, Tanner Buck, Anthony Huber et al. (+7 more)
Prime-Cam is a first-generation instrument for the Fred Young Submillimeter
Telescope (FYST), enabling wide-field, multi-frequency observations for cosmology, line-intensity mapping, and
galaxy studies. We present an optical performance study for a candidate 410 GHz broadband module designed to field approximately 21,000 polarisation-sensitive kinetic inductance detectors (KIDs). The three-lens silicon design was adapted from the SO LATR design and used for the existing 280 and 350 GHz
Prime-Cam instrument modules, as well as this study. At 410 GHz, a shorter wavelength places tighter demands on wavefront quality and beam shape. Using Ansys Zemax OpticStudio and Huygens PSF analysis, we evaluate candidate module positions, compare 350 and 410 GHz performance, and assess field-dependent Strehl ratio, ellipticity, and encircled-energy behaviour. A preliminary tolerancing study, using inverse increment and Monte Carlo methods, tests sensitivity to selected
alignment perturbations.
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All authors Tilak M. Patel, Tanner Buck, Anthony Huber, Eve M. Vavagiakis, James Burgoyne, Scott Chapman, Ben Keller, Jenna E. Moore, Michael D. Niemack, CCAT Collaboration
Instrumentation and Methods for Astrophysics
Foundation Models for Astrophysics
Xiaosheng Zhao and Yuan-Sen Ting
Foundation models are high-capacity networks pretrained once on broad data and then reused across many tasks. This chapter introduces them through the idea of a transferable representation, the internal description a network forms during training, which, rather than the fitted task, is what carries over to new problems. We develop the idea from first principles for an astronomical reader, starting from why a representation matters and what makes one useful, and then surveying the architectures, self-supervised objectives, scaling, adaptation, and cross-modal learning that produce one. A theme throughout is the distinction between these methods and the goal they serve. The presence of a
transformer, a self-supervised objective, and large-scale pretraining does not by itself make a model a foundation model, since the defining property is that the learned representation transfers, as tested by its ability to work on new tasks with little or no task-specific training data (few-shot and zero-shot learning). We then consider astronomy, where data are abundant but labels are scarce and simulations often stand in for ground truth. Here we offer a cautious reading of the current literature, in which many models adopt the architecture of foundation models while clear demonstrations of transfer across instruments, populations, and tasks remain comparatively rare. This is to be expected, since robust transfer beyond
language is still uncommon even in
vision and the wider physical sciences, and whether further scaling or a different account of representation will close the gap remains an open question. We close by placing the goal within the broader aim of machine intelligence and outlining the evidence that would mark real progress.
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Instrumentation and Methods for Astrophysics
Spatial Mapping and Capacitor Trimming Developments to Improve Usable Pixel Yield in PRIMA FIRESS Kilo-Pixel Arrays
Chris Albert, Jonathon Hunacek, Hien Nguyen et al. (+12 more)
The Probe far-Infrared Mission for Astrophysics (PRIMA) will use 8 kilo-pixel kinetic inductance detector (KID) arrays in its spectrometer module. We present an improved resonant frequency to spatial position mapping system designed to preserve each array's mapping after transferring it from the mapping apparatus to the flight housing. Such a mapping is necessary for astronomical observations, and additionally allows us to
laser trim the capacitive elements of KIDs to optimize resonance separation in frequency space. This increases the operating yield by eliminating collided resonances, reduces crosstalk, and reduces the sensitivity to frequency drift over time.
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All authors Chris Albert, Jonathon Hunacek, Hien Nguyen, Ritoban Basu Thakur, Andrew Beyer, Charles Bradford, Peter Day, Pierre Echternach, Byeong Ho Eom, Logan Foote, Marc Foote, Steve Hailey-Dunsheath, Reinier Janssen, Elijah Kane, Henry LeDuc
Instrumentation and Methods for Astrophysics · Cross-listed from astro-ph.SR
Performance of radio-based detection to operational monitoring M5+ class solar flares
Julia van Ravenswaaij, Ines Wilms, Ivan Ricardo et al. (+1 more)
Early detection of major solar
flares is critical for defense operations due to their potential to disturb radar and
radio systems. Typically, soft X-ray flux is used to monitor and classify solar
flares, but since this flux has to be measured in space, it means that its availability itself is dependent on space weather conditions. For this reason, in this paper, we investigated the feasibility of using ground
radio observations to monitor major (M5+ class) solar
flares. We made use of
datasets from the GOES-16 satellite and the
Radio Solar
Telescope Network in the time range between March 2023 and March 2025. An elastic net regularized logistic regression model was trained on this data, optimized through a grid search and with incorporated class weighting for class imbalance. It was found that especially higher frequencies (8800 MHz) had a reasonable ability in monitoring and predicting major
flares (precision and recall for
flare events are 53% and 65%, respectively - implying that roughly one third of
flares were not detected - with signals appearing, on average, 3 to 4 minutes before the M5 threshold is exceeded).
Radio measurements at super high frequencies can thus serve as an alternative method to monitor major solar flaring activity.
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All authors Julia van Ravenswaaij, Ines Wilms, Ivan Ricardo, Michaela Brchnelova
Instrumentation and Methods for Astrophysics
The Wetterstein Millimeter Telescope: A New German Facility for Astronomy and Geodesy
Alexander Neidhardt, Matthias Kadler, Anne-Kathrin Baczko et al. (+7 more)
The Wetterstein Millimeter
Telescope (WMT) is a planned broadband (1.2-120 GHz)
radio telescope to be established near the Environmental Research Station Schneefernerhaus (UFS) on Germany's highest mountain, the Zugspitze. Developed by a consortium of German research institutes and partners, the WMT is conceived as a multidisciplinary research infrastructure supporting
radio astronomy, geodetic VLBI, satellite communications, space situational awareness, and technology development. The
telescope is designed to operate within international VLBI networks, including the European VLBI Network, the Global mm-VLBI Array, and future ngVLA and SKA-VLBI observations. This contribution summarizes recent progress in the WMT project, including the
evolution of the
antenna design, and highlights the potential of the WMT to support future astronomical and geodetic VLBI.
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All authors Alexander Neidhardt, Matthias Kadler, Anne-Kathrin Baczko, Guido Dietl, Urs Hugentobler, Matthias Schartner, Tobias Ullmann, Till Rehm, Jompoj Wongphechauxsorn, for the WMT consortium
Instrumentation and Methods for Astrophysics
Pollux UV & FUV polarimeters: first lab results
Adrien Girardot, Ninon Demelier, Coralie Neiner et al. (+6 more)
Pollux is a high-resolution spectropolarimeter proposed by a European consortium for the Habitable Worlds Observatory (HWO). Its design covers a broad spectral range from the far-ultraviolet (FUV) to the near-infrared (97-1\,750 nm), with polarimetric channels relying on \ch{MgF2} birefringent optics in the mid- and near-UV (MUV-NUV), and on an innovative all-reflective polarimeter in the FUV, where no birefringent material is available. To validate these polarimeters, whose required polarimetric precision is $10^{-3}$, a dedicated
vacuum ultraviolet test bench has been developed, with two configurations: one for the MUV-NUV range (120-290 nm) and one for the FUV range (98-120 nm). We present the first laboratory results obtained with this bench. On the MUV-NUV configuration, the full optical chain has been integrated: a first polarised spectrum of the deuterium lamp was acquired, the polarisation generation subsystem was validated against Mueller
matrix predictions, and a first end-to-end polarimetric measurement was performed. On the FUV configuration, the windowless deuterium
plasma source has been characterised, the
alignment strategy of the K-mirror modulator has been implemented, and the mirror-based analyser has been manufactured and tested, showing a polarisation extinction ratio of 10 at 120 nm. These results demonstrate the operation of the bench and pave the way for the characterisation of the polarimetric precision of the Pollux polarimeters, increasing the Technology Readiness Level of UV spectropolarimetry for HWO.
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All authors Adrien Girardot, Ninon Demelier, Coralie Neiner, Jean-Michel Reess, Juan Ignacio Larruquert, Paloma Lopez-Reyes, Anejandro Garcia Canas, Nuria Gutierrez Luna, Ana Iglesias Moreno
Instrumentation and Methods for Astrophysics · Cross-listed from physics.ins-det
Spectroscopic study of argon electroluminescence light with a wavelength-sensitive particle detector
R. Santorelli, V. Pesudo Fortes, G. Vera Díaz et al. (+5 more)
We present a spectroscopic study of argon electroluminescence (EL) light in a gaseous time projection chamber (TPC). Using a compact detector equipped with photomultiplier tubes with different spectral sensitivities, we measure the light emission in two nominal wavelength regions, approximately [110, 160] nm and [160, 650] nm, at different gas pressures. In addition to the well-known 128 nm emission of the second continuum, significant emission is observed in the [160, 650] nm band, with a
prompt, nanosecond-scale response indicating that
photon production closely follows the transit of drifting electrons across the high-field EL region. In contrast, the [110, 160] nm emission displays a markedly slower time
evolution, dominated by excimer formation and de-excitation dynamics, with the light output governed primarily by the long-lived triplet component of the argon second continuum emission. We demonstrate that the full VUV pulse shape can be reproduced by convolving the fast UV3 response with excimer formation and decay functions, providing a coherent phenomenological interpretation of the observed signals. Our results provide new insights into the spectral and temporal properties of argon electroluminescence and have direct implications for the design and optimization of next-generation rare-event detectors based on gaseous TPCs. Further studies are underway to characterize this emission more precisely and to investigate its potential for particle discrimination.
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All authors R. Santorelli, V. Pesudo Fortes, G. Vera Díaz, C. K. Guérard, R. López Manzano, L. Luzzi, J. Martínez Morales, L. Romero
Instrumentation and Methods for Astrophysics · Cross-listed from astro-ph.HE
Parameter Estimation Horizon of Core-Collapse Supernovae with a Network of Gravitational-Wave Detectors
Almat Akhmetali, Y. Sultan Abylkairov, Solange Nunes et al. (+3 more)
Core-collapse
supernovae are among the most promising yet still undetected sources of gravitational waves. A future detection would provide a direct view of the physical processes occurring deep inside a collapsing
star. In this work, we investigate how networks of current and future gravitational-wave detectors can constrain the properties of rapidly rotating core-collapse
supernovae using their characteristic core-bounce and early post-bounce signals. Using deep-learning techniques, we estimate the peak frequency, rotation rate, and signal amplitude from noisy detector data and compare the performance of different detector-network configurations. We find that detector networks improve both parameter recovery and sky coverage. For current-generation networks, estimation of the peak frequency is possible out to about 30 kpc, while the rotation rate and signal amplitude remain recoverable out to distances exceeding 100 kpc. Third-generation observatories extend these distances by nearly an order of magnitude.
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All authors Almat Akhmetali, Y. Sultan Abylkairov, Solange Nunes, José Antonio Font, Michele Zanolin, Ernazar Abdikamalov