Instrumentation and Methods for Astrophysics · Cross-listed from physics.ao-ph
The iSTORM Instrument for Airborne Measurements of Gamma-Ray Emissions from Thunderstorms
Daniel Shy, J. Eric Grove, Bernard Phlips et al. (+7 more)
The in-Situ Thunderstorm Observer for Radiation Mechanisms (iSTORM) is a gamma-ray spectrometer to study gamma-ray transients originating from thunderstorms, such as glows and terrestrial gamma-ray flashes (TGFs). It is designed and built by the U.S. Naval Research Laboratory for deployment aboard a NASA ER-2 aircraft. Using an array of 32 one-inch-diameter $\mathrm{CeBr}_3$ scintillators read out with silicon photomultipliers (SiPMs), the instrument achieves an energy range of $\sim 250 \ \mathrm{keV}$ to $5 \ \mathrm{MeV}$ under flight conditions, with a total geometrical area of $157 \ \mathrm{cm^2}$. One of two gamma-ray instruments in the ALOFT campaign, iSTORM recorded glows, terrestrial gamma-ray flashes (TGFs), and the newly discovered flickering gamma-ray flashes (FGFs).
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All authors Daniel Shy, J. Eric Grove, Bernard Phlips, Alena Schell, Mary Johnson-Rambert, Mason Quick, David Corredor, Scott Podgorny, Roy Salinas, Mitch Davis
Instrumentation and Methods for Astrophysics
Modernising Observatory Control: Integrating Legacy DRAMA with Next-Generation Instrumentation
Mrunmayi S Deshpande, Nuria P F Lorente, Tony Farrell et al. (+1 more)
The DRAMA framework was originally developed at the Anglo-Australian Observatory (AAO) in the early 1990s, with its first release in 1992. Designed in C and C++, DRAMA provides a distributed, message-based control architecture that has powered major instruments such as the 2dF fibre positioner, fibre-fed spectrographs like AAOmega and HERMES, and the IRIS2 infrared imager on the Anglo-Australian
Telescope, and the TAIPAN instrument on the UK Schmidt
Telescope. Despite its age, DRAMA remains a robust and well-structured system whose real-time behaviour and modular task oriented design continue to be valuable for astronomical instrumentation. As new instruments are being developed at the AAO, we are extending and adapting the DRAMA environment to meet the current software engineering and deployment requirements. Our recent improvements include containerising DRAMA using Docker and a modern Python interface that enables integration without modifying the underlying codebase. This approach preserves the reliability of the original framework, and allows new instruments to adopt DRAMA within more flexible and maintainable ecosystems. At present, DRAMA continues to play an active role in our development efforts: it is being used for the newly built KSPEC spectrograph on the KMTNet
telescope, and also forms the control architecture for the high-resolution spectrograph being developed for the Devasthal Optical
Telescope.
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All authors Mrunmayi S Deshpande, Nuria P F Lorente, Tony Farrell, Satyam Mishra
Instrumentation and Methods for Astrophysics · Cross-listed from astro-ph.EP
Multi-epoch ultraviolet observables for breaking the radius-albedo degeneracy in directly imaged exoplanets
Suniti Sanghavi, Robert A. West and Pin Chen
Direct imaging measures how bright a
planet appears in reflected starlight, but brightness alone cannot tell whether the
planet is large and dark or small and bright. This radius-albedo degeneracy limits the characterization of non-transiting
exoplanets, including those targeted by the Habitable Worlds Observatory (HWO). From multi-epoch observations we construct ultraviolet observables that are independent of planetary radius: the normalized 400 nm lightcurve shape, the ultraviolet intensity and polarization colors, and the degree of linear polarization. In a clear 360-400 nm spectral window where Rayleigh scattering is strong and bright ultraviolet surfaces are nearly colorless, these observables constrain the atmospheric column, the surface reflectivity, and, when relevant, the observed phases before radius is inferred. Using the GPU accelerated vector radiative transfer model vSmartMOM, we test how uniquely these radius-free observables determine the scattering state at signal-to-noise ratios (SNRs) of 5, 20, and 100. For the chosen six phase sequence, spectropolarimetry gives median radius consequences of 9.5%, 3.3%, and 0.45% when the phases are known. If the phases are unknown, six distinct epochs keep the penalty modest at low SNR and negligible at moderate-high SNR, with median consequences of 14%, 3.2%, and 0.47%, respectively. Removing polarimetry degrades the result, especially in the HWO simulations where phase coverage is restricted by inner working angle. For solar twin systems at 6 and 12 parsecs, the required six-phase campaigns fall in the allotted range of a few hundred hours, making this a clear observing path to planetary radii from HWO's reflected-light detections.
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Instrumentation and Methods for Astrophysics
Optomechanical Design of the MANTIS SmallSat: An Extreme-, Far- and Near-Ultraviolet Spectrograph for Exoplanet Host Stars
Brian Fleming, Briana Indahl, Dmitry Vorobiev et al. (+16 more)
The MANTIS (Monitoring Activity of Nearby
sTars with uv Imaging and Spectroscopy) observatory is a compact, multi-instrument small satellite designed for simultaneous extreme- (EUV; 100 - 560 Angstrom), far- (FUV; 1150-1800 Angstrom) and near-ultraviolet/visible (NUV/VIS; 2000-6400 Angstrom) spectroscopy of low-mass
stars. The EUV optical system consists of a first-of-its-kind Hettrick-Bowyer grazing incidence
telescope contributed by the Italian National Institute for Astrophysics (INAF) feeding an advanced e-beam lithographic etched variable line spacing grating developed at Pennsylvania State University (PSU). The resulting low-resolution spectrum is imaged on an advanced microchannel plate detector with a potassium iodide (KI) photocathode for extremely low background noise, resulting in a limiting sensitivity for MANTIS that exceeds that of the last EUV-sensitive astrophysics point-source spectrograph, the Deep Survey/Spectrometer (DS/S) on EUVE. The FUV and NUV/Optical channels are fed by a compact rectangular
telescope that focuses onto a series of point-source apertures. The diverging beam is refocused and the FUV band dispersed by a holographic grating, then folded back onto the same detector as the EUV channel by a toroidal fold mirror. The zero-order light is picked off by a flat NUV grating, with the NUV/Optical spectrum recorded on an e2v CCD 42-10 detector. The MANTIS spacecraft is a custom build that leverages the experience derived from prior University of Colorado - LASP SmallSats for avionics, power, communications, and mechanical structure. MANTIS is projected to be completed in 2027 with an anticipated 2028 launch as an ESPA-class payload on a rideshare opportunity.
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All authors Brian Fleming, Briana Indahl, Dmitry Vorobiev, Kristina Davis, Kevin France, David Wilson, Nicholas Kruczek, Timothy Hellickson, Emily Farr, Marta Civitani, Davide Sisana, Kotish Grover, Laura Proserpio, Stefano Basso, Vincenzo Cotroneo, Fabien Grise, Randall McEntaffer, Oswald Siegmund, Adrian Martin
Instrumentation and Methods for Astrophysics
Visible-Light High-Contrast Polarimetry with MagAO-X: Characterization and Initial Results
Miles Lucas, Laird Close, Jared R. Males et al. (+22 more)
MagAO-X is a visible-light extreme adaptive optics instrument on the 6.5 meter Magellan Clay
Telescope, recently upgraded to enable high-contrast polarimetric differential imaging (PDI) in r', i', and z' filters. Polarimetry is a powerful technique for suppressing unpolarized starlight and isolating the faint, polarized signal scattered by circumstellar dust, but it demands precise calibration of instrumental polarization effects introduced by the
telescope and instrument optics. We present an overview of the MagAO-X polarimeter and characterize its polarimetric response using a purpose-built polarization generator that injects light of a known polarization state. From these measurements, we fit a Mueller-
matrix model of the instrument and quantify its polarimetric efficiency and instrumental polarization as a function of the k-mirror image rotator angle and observing filter. The initial characterization revealed significant, dynamic inefficiencies driven by the image rotator, motivating the deployment of a dual rotating quarter-wave plate (DQWP) compensator that dynamically reorients the input polarization to the instrument's eigenpolarization. Following installation of the DQWP, we measured an average increase in polarimetric efficiency of +17.5% (to 87.4%) and a reduction in instrumental polarization of -5.4% (to 8.3%) across all filters. Finally, we demonstrate the on-sky performance of the polarimeter with i' imaging of the debris disk around HR 4796, producing one of the closest inner-working-angle views of the bright, forward-scattering side of the disk. These results help pave the way for polarimeters on future extremely large
telescopes such as GMT and ELT.
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All authors Miles Lucas, Laird Close, Jared R. Males, Tiago Gualberto Bezerra de Souza, Rodrigo Pereira, Jialin Li, Joseph D. Long, Jaren N. Ashcraft, Kyle Van Gorkom, Olivier Guyon, Sebastiaan Y. Haffert, Alexander D. Hedglen, Rob G. van Holstein, Parker T. Johnson, Maggie Kautz, Jay Kueny, Briley L. Lewis, Joshua Liberman, Jennifer Lumbres, Eden McEwen, Avalon L. McLeod, Maxwell A. Millar-Blanchaer, Lauren Schatz, Katie Twitchell, Manxuan Zhang
Instrumentation and Methods for Astrophysics · Cross-listed from astro-ph.EP
Estimating Harmonic Coefficients of Asteroids through LiAISON Navigation
Jun Maruyama and Simone Servadio
This paper evaluates the Linked Autonomous Interplanetary Satellite Orbit Navigation (LiAISON) method in near two-body asteroid systems. While LiAISON's usefulness has been proven in multibody environments such as the cislunar region, the application of a two-body system with
gravity perturbations has not been sufficiently demonstrated. Vesta and Ceres are good candidates to test LiAISON, because the asteroids have sufficiently strong perturbations to use LiAISON method. The study utilizes a Multi-Model Adaptive Estimation (MMAE) framework integrated with Unscented Kalman Filters (UKF) to estimate the spacecraft states and perturbations using only range and range rate measurements. Results from the Monte Carlo analysis indicate that the proposed framework makes accurate and consistent estimates of position, velocity, and the perturbations for cases of Ceres and Vesta.
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Instrumentation and Methods for Astrophysics · Cross-listed from astro-ph.EP
Asteroid Disruption and Deflection Simulations for Multi-Modal Planetary Defense
Alexander N. Cohen, Philip Lubin, Darrel Robertson et al. (+7 more)
Planetary defense from asteroids via deflective means alone does not offer viable solutions in terminal scenarios where there is little warning time before impact. The PI method of planetary defense enables operation in terminal interdiction modes where there is little warning time prior to impact, but can also operate in the same extended time scale interdiction modes as made possible by traditional deflection techniques, which results in a versatile, multi-modal planetary defense capability. The method is also practical and cost-effective since it relies solely on launch vehicles and penetrator materials already available today, and thus presents itself as a logical and competitive option for planetary defense. As per the PI method, we investigate the effectiveness of rubble pile asteroid disruption and deflection via hypervelocity impacts with 10:1 aspect ratio cylindrical tungsten penetrators. We present the results of an ongoing simulation campaign dedicated to investigating the PI method, using the Lawrence Livermore National Laboratory (LLNL) arbitrary Lagrangian-Eulerian (ALE) hydrodynamics code ALE3D run with the High-End Computing Capability (HECC) at NASA Ames Research Center. We model heterogeneous rubble pile asteroids with a distribution of spherical boulders of varying initial yield strengths set within a weak binder material. We find that rubble pile asteroids of this type in the 20 - 100 meter-class can be effectively mitigated via 20 km/s impacts with 100 - 1000 kg penetrators via the coupling of the penetrator kinetic energy into the bulk material of the asteroid.
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All authors Alexander N. Cohen, Philip Lubin, Darrel Robertson, Mark Boslough, Sasha Egan, Brin Bailey, Angela M. Stickle, Elizabeth A. Silber, Peter Meinhold, Dharv Patel
Instrumentation and Methods for Astrophysics
AMReX-Astrophysics Microphysics: A set of microphysics routines for astrophysical simulation codes based on the AMReX library
AMReX-Astro Microphysics Team, Khanak Bhargava, Abigail Bishop et al. (+15 more)
The AMReX-Astrophysics Microphysics library provides a common set of microphysics routines (reaction networks and associated physics, equations of state, and various transport coefficients) as well as solvers (stiff ODE integrators, nonlinear system solvers) for astrophysical simulation codes built around the AMReX adaptive mesh refinement library (W. Zhang et al., 2019). Several multi-dimensional simulation codes, including the compressible hydrodynamics code Castro (Almgren et al., 2010), the low-Mach number hydrodynamics code MAESTROeX (Fan et al., 2019), and the radiation-hydrodynamics code Quokka (Wibking & Krumholz, 2022) use Microphysics to provide the physics and solvers needed to close the hydrodynamics systems that they evolve. The library is implemented in C++ with GPU-offloading a key design feature.
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All authors AMReX-Astro Microphysics Team, Khanak Bhargava, Abigail Bishop, Zhi Chen, Doreen Fan, Carl Fields, Adam M. Jacobs, Eric T. Johnson, Max P. Katz, Mark Krumholz, Chris Malone, Andy Nonaka, Piyush Sharda, Alexander Smith Clark, Frank Timmes, Ben Wibking, Don E. Willcox, Michael Zingale
Instrumentation and Methods for Astrophysics
Atmospheric Light Pollution by Proposed Reflect Orbital Space Mirrors
Miroslav Kocifaj, Gáspár Bakos and František Kundracik
ReflectOrbital is planning to launch a $18\times18$\,m mirror in space at a $\sim$600\,km altitude to illuminate a $2.5$\,km radius circular patch on Earth. The pilot satellite, called EARENDIL-1, is a pathfinder for a constellation of $\sim$50,000 larger mirrors, each with $54\times54$\,m in diameter, with the explicit goal to provide space-borne illumination on Earth. We calculate the sky brightness caused by the Rayleigh scattering and aerosol scattering of the incoming beam from one such satellite and by the light reflected back by the illuminated patch, for various atmospheric properties and ground albedos under cloud-free conditions. We demonstrate that the light pollution caused by one of these satellites is very significant, altering the nighttime environment up to distances of $\sim$30\,kms. The results show that for an observer within the beam of a single 54\,m satellite, the mirror will appear as a $-16.7$\,mag point-like source, i.e.~about 4 magnitudes brighter than the full moon. The diffuse sky background will be similar to the dusk sky shortly after sunset; too bright to see even the brightest
stars. From a distance of 14\,km, the glow from a single mirror will exceed the luminance of the full moon sky for majority of the sky. From a distance of 34\,km the sky will still appear brighter than the moon-lit sky in the direction of the beam. If 400 such mirrors illuminate the same patch simultaneously, the glow will be obvious from 80\,kms.
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Instrumentation and Methods for Astrophysics
The Early Career Astrobiology Workforce Under Strain Survey Evidence from 2025-2026
Katherine Dzurilla, Gabby Rizzo, Perianne Johnson et al. (+3 more)
A survey of self identified early career astrobiologists was organized by the NOW early career group FLOW and the Scientific Society of Astrobiology. During November 2025 to February 2026, 165 responses were collected to gain insight into the state of early career communities the impacts of federal grant delays on early career astrobiologists and the future of astrobiology. Results indicated that a majority of surveyed ECRs are concerned about their future careers (90 percent). Funding delays have affected 89 percent of ECRs future career paths, with open responses indicating that the lack of available funding resources, and employment opportunities limit their ability to see a future in the field. Most ECRs are unsure about staying in academia with over 50 percent of Ph.D. students, postdocs, and Junior scientists unsure or not planning to stay in academia. However Junior Faculty are largely planning to remain in academia.
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All authors Katherine Dzurilla, Gabby Rizzo, Perianne Johnson, Patrick Monreal, Ilankuzhali Elavarasan, Elizabeth Spiers
Instrumentation and Methods for Astrophysics · Cross-listed from astro-ph.SR
On the degeneracy of solutions from stellar spectropolarimetric data
J.C. Ramirez Velez, J.M. Raygoza-Romero, I.H. Lopez-Nava et al. (+3 more)
In this work we investigate the inversion accuracy of stellar
magnetic fields through the analysis of spectropolarimetric data. We performed several noise free tests to untangle the impact among the atmospheric and
magnetic parameters in the data analysis. Using a single spectral line, we found that under ideal scenario, without noise, the
magnetic parameters can be recovered with very high accuracy, while some of the atmospheric ones show a considerable incertitude. If multi-line profiles are considered instead, then the accuracy of the recovered atmospheric parameters increases significantly. Nonetheless, it is quite common that for the inversion of stellar spectropolarimetric data, the atmospheric parameters and the stellar inclination angle of the
star are fixed; we show that this procedure could induce very high errors in the inference of the
magnetic properties, specially in what concerns to fix the inclination angle. We show that even small deviations from the true inclination angles could have as consequence that the recovery of the
magnetic properties of the
star are no longer reliable. This is because we demonstrate that given a set of Stokes profiles observed along the rotational phase, they can be satisfactorily fitted regardless of the assumed stellar inclination angle, thereby revealing a degeneracy in the solution. Although this work validates the solution generation solely for a de-centered dipolar geometry, a comparable degeneracy is anticipated when modeling the
magnetic field with higher order spherical harmonics, an effect that remains to be formally characterized.
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All authors J.C. Ramirez Velez, J.M. Raygoza-Romero, I.H. Lopez-Nava, R. Lopez-Valdivia, M.F. Arenas, L. Adame Villanueva
Instrumentation and Methods for Astrophysics
NestyNet. II. Coherent Function-Space Posteriors from Scientific Neural Surrogates (or How to Avoid Expensive MCMC)
Rodrigo Ibata, Wassim Tenachi, Foivos Diakogiannis et al. (+2 more)
Scientific analyses increasingly use flexible neural networks, but their thousands of correlated parameters make it challenging to interpret the associated uncertainties. Here we develop a low-dimensional posterior for the fitted function itself, for scientific neural surrogates trained with second-order optimization. Linearizing the fitting procedure with respect to the randomized residual rows gives a measurement-to-function transport, the linear map, assembled from the converged Jacobians and Gauss–Newton
curvature, that carries measurement perturbations into the function perturbations that refitting would produce. Its leading singular functions define coherent deformation modes. Independent Gaussian coefficients then generate smooth function draws, so that any derived quantity, including those requiring derivatives or integrals of the draw, inherits the posterior. The construction distinguishes repeated-experiment covariance from the local Gauss–Newton/Laplace posterior and propagates both to correlated quantities of scientific interest. The result is conditional on the fit's declared choices (architecture, hyperparameters, active set, and optimization branch), and every fit is certified as converged by checking that a further optimization step would change the fitted predictions by less than a chosen small fraction of the measurement errors. Our primary example is an 800-parameter phase-space distribution function fit for a mock stellar disk. Four uncertainty coordinates, two orders of magnitude fewer than the fitted parameters and stable under refinement of the force basis, capture 99% of the vertical-force posterior variance, and 4000 coherent draws propagate through the force, total-density, surface-density, and frequency calculations in 0.8s. The method provides a highly efficient route to uncertainty propagation for derivative-dependent scientific inference.
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All authors Rodrigo Ibata, Wassim Tenachi, Foivos Diakogiannis, Neil Ibata, Anirudh Shankar
Instrumentation and Methods for Astrophysics · Cross-listed from astro-ph.EP
Veiled in Starlight: Impacts of Stellar Contamination on Retrievals of TRAPPIST-1f's Atmospheric Composition
Harper Rosenthal, Lisa Kaltenegger, Ryan J. MacDonald et al. (+2 more)
The TRAPPIST-1 system offers seven terrestrial
exoplanets with tight orbits and large radii ratios to the host
star. If an atmosphere exists, transmission spectroscopy can be used to detect specific atmospheric features. Predictions of the atmospheric detectability of the TRAPPIST-1
planets prior to the launch of JWST assumed pristine stellar surfaces. However, initial JWST observations of the TRAPPIST-1
planets demonstrate that stellar contamination from unocculted active regions imparts significantly stronger spectral features than any planetary atmospheres. Here, we evaluate the atmospheric detectability of the habitable zone
planet TRAPPIST-1f using atmospheric
retrievals accounting for stellar contamination. We model a transmission spectrum given a CO$_2$-rich, habitable atmospheric model, and we include a "worst case" stellar contamination spectrum. We then perform atmospheric
retrievals on simulated JWST observations with MIRI LRS (5-15 \micron) and NIRSpec PRISM (0.6-5.3 \micron), assuming accurate starspot spectral models. We find that NIRSpec observations alone achieve similar results as MIRI and NIRSpec together. We find $\sim$10 transits obtains strong evidence ($B>150$) for CO$_2$, and $\sim$50 transits finds weak evidence ($B>3$) for CH$_4$. We could not retrieve evidence of H$_2$O with up to 100 simulated transits with both instruments. Many challenges remain to accurately account for stellar contamination for ultra-cool M-dwarfs in atmospheric
retrievals, and our results show that, while evidence for a CO$_2$-rich atmosphere around TRAPPIST-1f can be found with a short JWST program, other prominent atmospheric signatures can only be disentangled from strong stellar features with more observation time than previous studies have indicated.
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All authors Harper Rosenthal, Lisa Kaltenegger, Ryan J. MacDonald, Rebecca Payne, Elijah Mullens
Instrumentation and Methods for Astrophysics · Cross-listed from physics.ed-ph
The Local Sky as an Introductory Solar System Astronomy Laboratory Using Smart-Telescopes
Roger M. Hart
Portable smart
telescopes can make introductory astronomy more observational, quantitative, and locally grounded by allowing students to acquire, share, and analyze astronomical images within a single class period. This article presents an eight-laboratory sequence for introductory Solar System astronomy using the Seestar S50 smart
telescope and archived or student-collected images. The sequence begins with a
galaxy-size investigation that introduces pixel scale, angular size, physical size, proportional
reasoning, and measurement uncertainty before students apply the same image-to-evidence approach to Solar System objects. Subsequent activities examine the positions and apparent motion of Jupiter's Galilean moons, comparative planetology and
telescope limitations, the apparent sizes of Mars, Jupiter, and Saturn, lunar phase and angular diameter, relative lunar surface history through crater-density comparisons, single-session solar activity, and multi-day sunspot tracking to estimate solar rotation. Each investigation follows a 5E-informed structure and produces a focused student product, such as a measurement table, graph, comparison chart, or claim-evidence-
reasoning statement. Throughout the sequence, students must define transparent measurement rules, distinguish direct observations from interpretations, and evaluate how image scale, illumination, exposure, seeing, target visibility, and boundary selection constrain their conclusions. The activities are designed for high-school, dual-enrollment, community-college, and introductory university astronomy courses and may be implemented with live observations or prepared image sets when weather, scheduling, or local observing conditions prevent data collection.
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Instrumentation and Methods for Astrophysics
A space of inference spaces in the space sciences - parametric Bayesian inference in astronomy, cosmology and particle physics
Johannes Buchner
A sample of parametric
Bayesian inference applications from astronomy, cosmology and particle physics is studied, augmented by mock data sets and toy problems. The parameter spaces of these parametric physical models and their posterior distributions from analysing specific data are characterized by (1) the number of model parameters, (2) whether the posterior shape is similar to a Gaussian, (3) whether the posterior has light or heavy tails, (4) how small the posterior is compared to the prior, i.e., how informative the data are, (5) whether some parameters remain unconstrained while others are highly constrained, (6) whether the posterior has multiple, disconnected modes, and (7) whether the inference undergoes phase transitions. These axis define a parameter space of inference problems. We characterize each of the inference problems and observe that inference in astrophysics spans the entire parameter space, from low to high dimensionality, mono- to multi-modal, and a variety of complex distributions that range from uninformative to highly informative. Furthermore, the computational cost of the physical models can range from milliseconds to dozens of seconds. The collated sample of inference problems is proposed as a standard test bed for new samplers. For reproducibility and ease of use, a Docker compute image is provided.
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Instrumentation and Methods for Astrophysics · Cross-listed from gr-qc
Coherent End-to-End Search for Generic Extreme-Mass-Ratio Inspirals
Xiaobo Zou, Xingyu Zhong, Wen-Biao Han et al. (+1 more)
Extreme-mass-ratio inspirals (EMRIs) encode more than $10^5$ strong-field orbital cycles and are key targets for space-borne gravitational-wave interferometers, yet coherent recovery of generic systems over astrophysically broad priors remains unresolved. Successive Mock LISA, LISA, and Taiji Data Challenges (MLDCs, LDCs, and TDCs) have not yet produced a complete, generally reliable solution for blind EMRI detection and parameter recovery across such priors. The central obstacle is a needle-in-a-haystack likelihood: six phase-
evolution parameters span a vast domain, producing an exceptionally narrow global maximum amid numerous secondary maxima. We show that higher-likelihood secondary maxima concentrate progressively around the global maximum and can therefore guide an adaptive contraction of the search volume. We exploit this structure through a reduced-dimensional profile likelihood and a coherent hierarchical strategy to search for EMRI signals across the full 14-dimensional parameter space. This enables the first end-to-end coherent parameter estimation for generic EMRIs with astrophysically broad priors. In stationary Gaussian LISA noise, the search recovers two half-year analytical-kludge signals with signal-to-noise ratios near 50, yielding fitting factors of 0.989 and 0.971, fractional errors of $10^{-3}$–$10^{-2}$ in the phase-
evolution parameters and near $3\%$ in the distance, and error of less than $0.1$ radian in the sky location. The method turns secondary maxima into guides for a coherent hierarchical search.
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All authors Xiaobo Zou, Xingyu Zhong, Wen-Biao Han, Soumya D. Mohanty
Instrumentation and Methods for Astrophysics · Cross-listed from astro-ph.GA
Optical Counterparts of MeerKLASS L-band and UHF-band surveys
M. Klein, S. Mangla, J. Mohr et al. (+7 more)
Context: Wide-area
radio continuum surveys require reliable optical and infrared counterpart identification, but high optical source densities and extended or multi-component
radio morphologies make this challenging. Aims: We present optical and infrared counterpart catalogs for MeerKLASS L-band and UHF-band on-the-fly continuum sources using KiDS DR5 and DESI Legacy Imaging Surveys DR10 (LS DR10), including counterpart probabilities,
redshifts, and host-
galaxy properties. Methods: We developed the Stellar-mass Enhanced Density Association (SEDA) method, an empirical framework that compares candidate densities around
radio positions with those in a position-displaced control catalog. For
galaxies we use positional offset, stellar mass, and
redshift;
quasar candidates are treated separately using offset and mid-infrared selection. A second-pass search associates multi-component
radio sources with common hosts. Results: In the L-band survey, we identify 20,400 KiDS-based counterparts with $P_{\rm true}>0.5$, corresponding to 66% of L-band sources within the KiDS footprint. In the UHF-band survey, we identify 61,633 LS DR10 counterparts, corresponding to 81% of the
radio sources. Spectroscopic
redshifts are available for 22% and 44% of the L-band and UHF-band counterparts, respectively. The
redshift distributions show low-
redshift star-forming
galaxies, intermediate-
redshift radio galaxies, and a high-
redshift tail dominated by
quasars. SEDA also recovers rare
radio-loud
quasars, including QSO J2318-3113 at $z=6.44$ and UHF_DR1 J+111111.8+053626.6 at $z=5.24$. Conclusions: SEDA provides a data-driven route to counterpart identification for wide-area
radio surveys with complex source morphologies. The catalogs enable future MeerKLASS studies of
radio source populations, host-
galaxy demographics, and rare high-
redshift radio quasars.
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All authors M. Klein, S. Mangla, J. Mohr, S. Chatterjee, K. Grainge, S. Paul, M. G. Santos, O. M. Smirnov, C. Tasse, L. Wolz
Instrumentation and Methods for Astrophysics · Cross-listed from astro-ph.EP
Exploration of Exoplanet Atmospheres with the James Webb Space Telescope
Sasha Hinkley and David K. Sing
The James Webb Space
Telescope (JWST) is providing transformative characterization capabilities for the study of both transiting and directly imaged extrasolar
planets. Observations deep into the infrared in the form of both spectroscopy and coronagraphic imaging means that JWST is uniquely sensitive to most of the physical processes that dictate the properties of exoplanetary atmospheres. The observatory's thermal and pointing stability directly translates into the extreme photometric precision needed for exquisite transiting
exoplanet photometry, as well as highly sensitive coronagraphic observations. Over the mission's 20-25 year lifetime, roughly 10$^4$ hours will be dedicated to observations of
exoplanet atmospheres, providing a legacy data archive that will allow population-level characterization of
exoplanet atmospheres spanning terrestrial
planets, sub-Neptunes and gas giants. This effort will also assess the prevalence of atmospheres of rocky
planets and thus the degree to which such
planets may have conditions conducive to habitability.
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Instrumentation and Methods for Astrophysics
NestyNet. I. Physics Functions Are Hard to Fit with Neural Networks: A Framework for Accurate Surrogates and Analytic Derivatives
Rodrigo Ibata, Wassim Tenachi, Foivos Diakogiannis et al. (+2 more)
Many of the smooth functions that matter most in physics are precisely the ones that standard neural network methods struggle to fit accurately. Here we present NestyNet, a coupled model-and-optimizer framework capable of fitting such targets to high accuracy while also delivering their gradients, Hessians,
Laplacians, and antiderivatives analytically and at low cost. This makes it a natural substrate for scientific machine learning tasks. The model is a deterministic segmented analytic surrogate, and its optimizer is a second-order Levenberg–Marquardt scheme whose damping and linear solves are tailored to the stiff, strongly correlated parameter geometries induced by multiscale and sharply structured targets typical in physics and other scientific applications. On the AI Feynman
benchmark of 120 physics equations, NestyNet achieves median improvement factors of $2\,100\times$ for function values, $1\,400\times$ for first derivatives, and $780\times$ for second derivatives relative to standard neural networks trained with first-order optimization (Adam). Even after refining those fits with quasi-Newton (L-BFGS) optimization, the corresponding improvements are $540\times$, $450\times$, and $250\times$. Owing to the analytic design it is up to $\approx 44\times$ faster than vectorized automatic-differentiation (autograd) baselines, with a margin growing with model size. The same analytic-derivative framework also supports vector- and complex-valued targets, measurement uncertainties in both inputs and outputs, and constraints, and its modules can be composed flexibly to build scientifically useful model architectures, all without reverting to autograd. Together, these components provide a practical modular framework for fitting difficult scientific surrogates while delivering accurate differential operators for subsequent analysis.
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All authors Rodrigo Ibata, Wassim Tenachi, Foivos Diakogiannis, Neil Ibata, Anirudh Shankar
Instrumentation and Methods for Astrophysics
GRAVITY+: reducing non-common-path aberrations for sub-10 {\mu}as astrometric accuracy
Quentin Fournier, Guillaume Bourdarot, Frank Eisenhauer et al. (+26 more)
GRAVITY is a state-of-the-art instrument for near-infrared astrometric interferometry that routinely achieves astrometric accuracy of 30-100 microarcsecond in its phase-referenced dual-field mode. However, its fundamental limit is not yet reached, and can still be improved by several factors. In this paper, we focus on the effect of systematics, and in particular the effect of non-common path aberrations between the science channel and the metrology signal in the
GRAVITY Fiber Coupler. Through comprehensive laboratory measurements using a dedicated fiber coupler replica and phase-shifting interferometry at 1908 nm, we have characterized these high-order wavefront errors with nanometer precision in the laboratory. We characterized on-sky the effect of these high-order wavefront imperfections on narrow-angle astrometry, using observations of the binary system GJ65. As part of the
GRAVITY+ project, high-precision mirrors designed for nanometer-level surface quality, bringing an order of magnitude improvement over existing
GRAVITY injection optics, are currently in production and will be installed in the fiber coupler units by the end of 2027. This upgrade is expected to enable astrometric accuracy at the sub-10 microarcsecond level in dual-field mode with integration times of just a few minutes.
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All authors Quentin Fournier, Guillaume Bourdarot, Frank Eisenhauer, Helmut Feuchtgruber, Dieter Lutz, Etienne Rosin, Stefan Gillessen, Reinhard Genzel, Taro Shimizu, Oliver Pfuhl, Felix Mang, Michael Hartl, Thomas Ott, Ekkehard Wieprecht, Vishaal Gopinath, Françoise Delplancke-Stroebele, Luis Esteras Otal, Felix Widmann, Sebastiano von Fellenberg, Pierre Bourget, Guy Perrin, Julien Woillez, Paulo Garcia, Sebastian Hönig, Laura Kreidberg, Jean-Baptiste Le Bouquin, Thibaut Paumard, Christian Straubmeier, for the GRAVITY+ Collaboration
Instrumentation and Methods for Astrophysics
MARS: A Lightweight Morphology-Aware RFI Segmentation Network for Mask-Guided Mitigation in Radio Astronomy
Zhaocheng Gong, Jack White, Jayanta Roy et al. (+1 more)
Next-generation
radio telescopes generate filterbank data at rates that make storing all observations for later offline mitigation impractical. Mitigation must therefore operate in real or near-real time within the search pipeline while preserving dispersed astrophysical signals. CPU tools fit GPU-centred search pipelines poorly, while neural alternatives can be computationally heavy. We present MARS, a GPU-based RFI mitigation pipeline centred on a lightweight Morphology-Aware RFI Segmentation Network. The model is a reduced-width, full-resolution U-Net with a bottleneck containing local, horizontal, and vertical filters to capture compact and elongated RFI structures in the frequency-time plane. Normalisation, patch construction, mask reconstruction, replacement, baseline removal, and output rescaling are also implemented on GPU. Training includes an astronomical-signal preservation loss that discourages false flagging of dispersed pulses. In controlled patch-level tests, MARS achieves an RFI-mask F1 score of $0.978$ and a precision of $0.995$. It retains $97.6\%$ of the injected dispersed-signal fluence in clean patches and $96.4\%$ of the non-overlapping signal fluence in patches containing mixed injected RFI. Ablation experiments show that the astronomical-signal preservation loss particularly improves the protection of compact, low-DM, high-S/N pulses. At filterbank level, period-matched PRESTO candidates recovered after MARS mitigation have median significance ratios of $0.90$–$0.99$ relative to filtool. Both methods also recover the known
pulsars in two real GMRT observations. On an NVIDIA GH200 GPU, MARS achieves a compute-only speedup of $6.2\times$–$7.0\times$ over the fastest tested multi-threaded filtool configurations on an AMD EPYC 9825 CPU.
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All authors Zhaocheng Gong, Jack White, Jayanta Roy, Wesley Armour