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Physics Astrophysics Instrumentation and Methods for Astrophysics

astro-ph.IM Watch Instrumentation and Methods for Astrophysics

Sunday 23 August

Instrumentation and Methods for Astrophysics · Cross-listed from gr-qc

Correlated and coincident noise in Einstein Telescope's triangular configuration

Jan Harms

The Einstein Telescope (ET) is a proposed underground infrastructure in Europe to host future generations of gravitational-wave (GW) detectors. Two configurations are under investigation. The first is the two-site solution with an L-shape detector at each site similar to the LIGO configuration. The second configuration is the single-site triangular detector. While numerous analyses over the last decade have already proven that the distributed network of GW detectors is the scientifically preferred solution, it was also argued that the advantage might not be decisive enough to dismiss ET's triangle configuration. The modeling of aspects such as noise correlations in these configurations has only been treated superficially in the past. In this article, we introduce a time-domain simulation of environmental noises in the ET triangle using available data from ET's candidate sites. We simulate and analyze correlated environmental noise as well as coincident glitches produced by transients in the environmental fields. We find that these features pose an important limitation to the observational capabilities of the ET triangle and limit the utility of its null stream.
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Instrumentation and Methods for Astrophysics

Automated Shape-Model-Based Astrometry of Phobos from Mars Express SRC Images

Wangxin Lai, Qingfeng Zhang, Rui Zhang et al. (+4 more)

High-resolution spacecraft images provide important astrometric constraints for orbit refinement, but measurements of resolved bodies are often limited by labor-intensive control-point selection and the difficulty of achieving consistent reductions over large image archives. We present an automated shape-model-based astrometric pipeline for Phobos and apply it to Mars Express Super Resolution Channel (SRC) images. For each exposure, a synthetic image is rendered from a high-resolution 3D shape model under the nominal spacecraft-target-Sun geometry. Feature correspondences between the observed and synthetic images are established using SuperPoint and SuperGlue, followed by RANSAC filtering. The matched synthetic-image keypoints are then associated with surface points through ray-shape intersection. The geometric adjustment fixes the adopted body orientation, spacecraft state, and corrected camera pointing and estimates only two effective plane-of-sky position offsets using the exact perspective-projection model. These offsets are used to derive the center-of-figure position of Phobos. We first test the method on an image set previously analysed with a control-point approach and obtain comparable astrometric performance. We then extend the analysis to a larger SRC dataset spanning 2007-2025 and obtain 1113 successful measurements. Relative to the JPL MAR099 ephemeris, the resulting observed-minus-computed residuals have mean values of 0.186 km in $\alpha \times cos(\delta)$ and 0.053 km in $\delta$, with corresponding standard deviations of 0.609 km and 0.583 km. These results demonstrate that the proposed pipeline provides a practical approach to large-scale, homogeneous astrometric reduction of archival spacecraft images of Phobos, with potential application to other resolved bodies.
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All authors Wangxin Lai, Qingfeng Zhang, Rui Zhang, Kai Tang, Chunyu Ding, Zhan Li, Haipeng Wang

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

Assessment of the 5 August 2026 Falcon 9 Upper-Stage Lunar Impact: Energetics, Crater Scaling, and Comparison with LRO Observations

Mavia Anjum

The objective of this study was to characterize the human-made object that impacted the Moon on 5 August 2026, to estimate the dimensions of the crater it produced, and to compare the estimates with the crater subsequently measured by the Lunar Reconnaissance Orbiter (LRO). The impactor was the discarded upper stage of a SpaceX Falcon 9 rocket, which struck the surface near Einstein crater at a velocity of 2.43 km/s. The kinetic energy and linear momentum of the impactor were calculated, and the crater diameter was estimated using pi-group scaling relationships and measured rocket-body impacts as empirical analogs. The kinetic energy of the impactor was found to be 1.18 x 10^10 J, equivalent to approximately 2.8 tonnes of TNT. Compact-body pi-group scaling yielded a final rim-to-rim diameter of 46-57 m, and the empirical analogs yielded 26-27 m, leading to a pre-observation preferred estimate of 25 m within a range of 20-30 m. Between 11 and 12 August 2026, LRO imaged a crater approximately 18 m in diameter and less than 3 m deep. The results revealed that the compact-body scaling overpredicted the observed diameter by a factor of 2.6-3.2, whereas the empirical-analog method overpredicted it by 39-50%. When the nearest-mass analog was applied as a single crater rather than as a double crater, the estimated diameter was approximately 18 m, in close agreement with the observation. It was found that the hollow and elongated geometry of the stage, rather than a single equivalent bulk density, is the principal factor governing the crater size. This study provides a direct comparison of impact-scaling methods against a measured artificial lunar crater.
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Instrumentation and Methods for Astrophysics

Variational Bayesian Inference for the Spectral Structure of LISA Noise

Jianan Liu, Avi Vajpeyi, Renate Meyer et al. (+2 more)

Estimating spectral density matrices for future space-based gravitational-wave detectors such as LISA is challenging due to the long duration of the data and the correlated instrumental noise across multiple time-delay interferometry channels. In this work, we investigate a specialized mean-field stochastic gradient variational Bayes (SGVB) procedure for fast posterior approximation in long-duration multivariate spectral density estimation. Based on the existing eigenbasis representation of the blocked Whittle likelihood approach, the posterior model applies a Cholesky factorization to represent the inverse spectral density matrix and models the resulting frequency-dependent entries with cosine basis functions, with a discounted regularized horseshoe prior assigned to the basis coefficients. We test mean-field SGVB as a stand-alone posterior approximation by comparing it with Hamiltonian Monte Carlo (HMC) targeting the same posterior model. In simulation studies based on autoregressive and moving average processes, SGVB produces posterior median spectral estimates close to those obtained from HMC at substantially lower computational cost. We then apply the method to two one-year, fixed-delay, stationary, noise-only LISA simulations and show that the SGVB spectral density estimates are consistent with HMC and Welch estimates across the LISA analysis band, while requiring substantially less computation. These results demonstrate that SGVB provides a scalable Bayesian approach to spectral density estimation for long-duration multivariate LISA noise analysis.
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All authors Jianan Liu, Avi Vajpeyi, Renate Meyer, Jeung Eun Lee, Patricio Maturana-Russel

Instrumentation and Methods for Astrophysics

Modeling the technical specifications for future multi-object spectroscopy instrumentation

Ummee Tania Ahmed, Andrew Hopkins and Simon Ellis

We investigate a proof-of-concept code designed to model the functionality of current generation astronomical fiber positioner instruments. This code accommodates an arbitrary number of fiber probes and astronomical targets. To establish the prerequisites for future fiber positioning technologies, we conduct a systematic analysis of both the observational and instrumentation parameter space (such as target density, fiber density, and exclusion and patrol radius). The tool assesses the efficiency and completeness of such a system by modeling the allocation of fibers to targets over multiple visits or observations, enabling the quantification of performance based on the specific parameters. This tool holds significance in delineating the technical specifications for future multi-object spectroscopy instrumentation. This will inform the development of new technologies for the next generation of telescopes using novel instrumentation techniques or the extension of existing technologies.
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Saturday 22 August

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

AstroBind: Machine learning prediction of binding energy distributions on interstellar water ice from geometric surface descriptors

Aneesa Ahmad and Catherine Walsh

Binding energies on amorphous solid water regulate molecular desorption in molecular clouds and protoplanetary disks, but computing them from first principles across the heterogeneous binding sites of disordered ice surfaces is computationally prohibitive. We aim to develop a rapid, interpretable method for predicting binding energies on amorphous solid water that captures surface heterogeneity without requiring explicit electronic-structure calculations. We trained a machine-learning model using 27 geometric descriptors of the local ice-adsorbate environment. The model was trained on binding energies for 13 adsorbates on amorphous solid water clusters and evaluated through pooled leave-one-cluster-out validation across 15 ice surfaces. Its transferability was assessed on radical species excluded entirely from training. The model achieves a pooled leave-one-cluster-out coefficient of determination $R^2 = 0.90$ (the fraction of variance in the binding energies captured by the model, where 1 is a perfect fit), and a mean absolute error of 378 K across 15 ice surfaces. It also transfers to radical species withheld from training, with a pooled $R^2 = 0.79$, although its accuracy decreases when the unpaired electron contributes directly to the surface interaction. Our results demonstrate a route towards rapid, distribution-aware parameterisation of binding energies and desorption/diffusion rates in gas-grain astrochemical models, while preserving physical interpretability on heterogeneous ice surfaces.
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Friday 21 August

Instrumentation and Methods for Astrophysics

The influence of standard relativistic effects on Gaia-like astrometric catalogs

Gabriel Rodríguez-Moris and Sergei A. Klioner

With the observational accuracy of astrometric space telescopes such as Gaia, the Newtonian theoretical framework for positional astronomy is no longer appropriate. To model all effects relevant at the corresponding levels of accuracy, a more sophisticated description in the framework of General Relativity is required. It is generally known how various relativistic effects affect a given astrometric observation. In particular, the maximal light deflection of a given Solar System body can be easily estimated for a given observer. However, astrometric parameters for a given source are computed from a series of observations of that source. Depending on the relativistic effect, the fraction of observations affected, at some given level of accuracy, by that relativistic effect can vary and also be very small. Our goal is to investigate the impact of unaccounted relativistic effects on the astrometric parameters of a source observed by a Gaia-like astrometric telescope. The standard relativistic framework for Gaia is used to highlight such effects in some cases where they are most significant. Then, using the simulation tool AGISLab, we fit a set of Gaia-like observations of a given number of sources to the standard Gaia-like astrometric model for astrometric source parameters, but using different incomplete relativistic models. In this way we obtain the errors of the astrometric parameters if one were to drop different elements of the relativity model. A simplified analytical description of the errors is also provided and discussed. We demonstrate that, due to averaging over many observations per source, the errors in the astrometric parameters are drastically smaller than the corresponding relativistic effects in individual observations. This opens a way to potentially simplify the relativistic model for future astrometric projects aiming for higher accuracy than Gaia.
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Instrumentation and Methods for Astrophysics · Cross-listed from astro-ph.CO

Simulation Tests of PSF Modeling for Cosmic Shear with the Vera C. Rubin Observatory

Claire-Alice Hébert, Erin S. Sheldon, Tianqing Zhang et al. (+3 more)

Exceptional control of systematic effects is required in order to achieve unbiased cosmic shear two-point correlation function measurements with the next generation of galaxy imaging surveys, such as the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST). One critical challenge is accurately modeling the point-spread function (PSF), as errors in PSF estimation can introduce spatially correlated biases in galaxy shape measurements. The LSST Science Pipelines, which will be used to process Rubin data, include an implementation of the PIFF (PSFs in the Full Field of View) package originally developed for, and demonstrated to perform well on, DES-Y3 and Y6 data. In this work we use semi-realistic image simulations, mimicking LSST observing conditions in $i$-band over 100 square degrees, to perform an end-to-end test of the Rubin PSF modeling pipeline. PSF model residuals are quantified using both second- and fourth-order moment parameters and performance is evaluated, for both LSST year 1 and year 10 depth, with a series of diagnostic tests. We find that the additive bias contribution from PSF modeling errors to the non-tomographic cosmic shear data vector is well below 30% of the cosmic shear uncertainty estimated from our analytic covariance matrix. Though our simulations exclude several known effects that may further challenge PSF modeling, these results demonstrate promising performance from PIFF on LSST-like data and provide an early benchmark for ongoing PSF validation efforts for LSST weak lensing analyses.
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All authors Claire-Alice Hébert, Erin S. Sheldon, Tianqing Zhang, Joachim Harnois-Déraps, Mike Jarvis, the LSST Dark Energy Science Collaboration

Instrumentation and Methods for Astrophysics

Image persistence flagging for SPHEREx

Candice Fazar, C. Darren Dowell, Brendan P. Crill et al. (+3 more)

Image persistence in HAWAII-2RG HgCdTe detectors has been observed by multiple parties. Also known as latent signal, this effect occurs when sensor images following an illumination show a decayed form of the illuminated image even though the source has been removed and the detector has been reset. Using data from an engineering grade detector array delivered for SPHEREx testing illuminated with a wide range of fluxes, we demonstrate an interpretation and a working model from which the decaying signal can be estimated, providing the ability to flag pixels subject to excess persistence current beyond a specified threshold. Simulated persistence images allow validation of the module and prediction of its effect in flight data.
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All authors Candice Fazar, C. Darren Dowell, Brendan P. Crill, Phil Korngut, Chi Nguyen, Howard Hui

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

Assessing the Impact of High-Resolution Imaging on Statistical Validation of TESS Planet Candidates

Michael Collier, Steven Giacalone, Brian Derfer et al. (+38 more)

High-resolution imaging is widely used to constrain false-positive scenarios in exoplanet validation, but it is a finite follow-up resource that reaches only a subset of candidates, and its population-level impact on validation outcomes has not been quantified through controlled removal experiments. Using an automated pipeline built on TRICERATOPS, we compute the false-positive probability (FPP) of 443 TESS planet candidates. For the 264 planet candidates with high-resolution imaging observations, we compute FPP with and without the corresponding contrast curves, allowing us to quantify the impact of the additional data. We find that 72% of 68 contrast-curve bearing validated planets would fail validation without their adopted contrast curves. The fraction requiring imaging decreases with increasing planet size, from 100% below $1.7~R_\oplus$ to $33\%$ above $4~R_\oplus$: within our sample and TRICERATOPS-based analysis, the availability of high-resolution imaging directly limits the yield of small-planet validation and the supply of validated targets for atmospheric characterization. Our analysis statistically validates 64 new TESS planets with sizes spanning 0.94 to 7.83 $R_\oplus$ across hosts of spectral type M through F. Four of these are highly amenable to JWST observations based on the transmission and emission spectroscopy metrics, and each achieves validation only with its imaging constraint.
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All authors Michael Collier, Steven Giacalone, Brian Derfer, David R. Ciardi, Catherine A. Clark, Ian J. M. Crossfield, Sarah Deveny, Sergio B. Fajardo-Acosta, Elise Furlan, Emily A. Gilbert, Steve B. Howell, Adam L. Kraus, Rachel A. Matson, Joshua E. Schlieder, Julian C. van Eyken, David Baker, Khalid Barkaoui, Özgür Baştürk, Mario Basilicata, Izuru Fukuda, Akihiko Fukui, Mourad Ghachoui, Michaël Gillon, Emmanuel Jehin, Jerome de Leon, Luigi Mancini, Francesca Manni, Gabriel Murawski, Bob Massey, Luca Naponiello, Norio Narita, Justus Randolph, Roberto Zambelli, Richard P. Schwarz, Abderahmane Soubkiou, Gregor Srdoc, Chris Stockdale, Toshi Suganuma, Jiaqi Wang, Francis P. Wilkin, Selçuk Yalç{\i}nkaya

Instrumentation and Methods for Astrophysics

On the performance of pre-trained vision transformers for supernova spectral classification using different spectral representations

J. Serrano Bell, P. Gálvez Molina, V. Contreras Rojas et al. (+4 more)

The spectroscopic classification of supernovae is a key component of time-domain astronomy and plays an important role in the identification of Type Ia events. The increasing volume and diversity of spectroscopic data motivate the development of automated classification approaches. In this work, we explore the use of Transformer-based vision models for supernova spectral classification, focusing on how different visual representations of spectra and fine-tuning strategies affect classification performance when image-based architectures are applied to intrinsically one-dimensional data. We consider a dataset of 4,011 supernova spectra, augmented and rebalanced into three astrophysically motivated classes: normal Type Ia, other Type Ia subtypes, and core-collapse supernovae. Spectra are encoded as line-plot images using direct flux-wavelength visualizations as well as alternative flux-difference versus wavelength-difference heatmap representations designed to emphasize differential spectral structure. We evaluate several pre-trained Transformer architectures, including Vision Transformers (ViT), Swin Transformers, and a DINOv3-pretrained ViT, and examine the effects of fine-tuning depth, visual representation, and hyperparameter choices. We find that a plain flux-wavelength line plot outperforms the purpose-built maps on average, though log-scale maps remain competitive for specific architecture and fine-tuning combinations. On the held-out test set, our best model (vitb-p16) reaches a macro-F1 score of 86.3%, with per-class F1 scores of 94% for normal Ia, 77% for other Ia subtypes, and 88% for core-collapse supernovae. The dominant misclassification arises from confusion between Ia-91T and normal Ia spectra. These results demonstrate that Transformer-based vision models can provide competitive performance for single-spectrum supernova spectral classification.
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All authors J. Serrano Bell, P. Gálvez Molina, V. Contreras Rojas, W. Fox Fortino, M. Rojas, P. Protopapas, F. Bianco

Instrumentation and Methods for Astrophysics

NestyNet. IV. Laws Chosen by Nothing in Advance

Rodrigo Ibata, Wassim Tenachi, Foivos Diakogiannis et al. (+2 more)

Differential-equation (DE) discovery tends to break down precisely where much of physics begins. Fields are coupled, governing laws are nonlinear in the state, amplitudes, coordinates, or operators of interest, yet derivatives must remain consistent across fields, channels, and differentiation orders. NestyNet-DE addresses this via two complementary DE search strategies, both employing analytic derivatives from segmented neural surrogates: a sparse-library route linear in the outer coefficients, and a new operator-factorized route that searches directly over equation structure rather than a fixed library, recovering compositional laws the sparse route misses. The recovered laws can be strongly nonlinear in states, fields, coordinates, and their couplings. The framework also handles multi-dataset shared-support discovery, complex and vector laws, and Hamiltonian discovery from phase-space trajectories. Beyond a law's form, the same data yield its geometry, the Lie point symmetries of the recovered equation. We apply the pipeline to 30 years of daily ephemerides of $308$ main-belt asteroids and recover the reduced-Kepler hierarchy (areal law, inverse-square force, and reduced Hamiltonian), where a discovered rotational symmetry fixes the centrifugal coefficient rather than fitting it. We also present a benchmark of 57 real-valued ODEs and 26 complex-valued systems, including the Schrödinger and Dirac equations, with Maxwell's equations as a coupled vector-PDE case study. Here, discovery is not shackled to a fixed library, nor does it end at the equation. It composes laws that no dictionary anticipated, and closes the loop from data, to a law chosen by nothing in advance, to the geometry that explains and integrates it.
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All authors Rodrigo Ibata, Wassim Tenachi, Foivos Diakogiannis, Neil Ibata, Anirudh Shankar

Instrumentation and Methods for Astrophysics

Radio Galaxies detection and characterization using deep learning techniques

Sanjay Khatik, Rohit Sharma and Pankaj Jain

Future radio telescopes will generate data volumes that are increasingly difficult to analyse using traditional statistical methods, motivating the adoption of machine-learning techniques. In this work, we present YOLO-Chars (YOLO-based Detection and Characterisation of Radio Sources), a two-stage deep-learning framework for the automated detection and characterisation of radio galaxies in survey images. The framework is developed and evaluated using the Square Kilometre Array Science Data Challenge 1 (SKA SDC1) dataset. In the first stage, customised YOLO-based multi-scale detection models are used to localise compact and extended sources across large sky maps. In the second stage, a dedicated source-characterisation network estimates the physical properties of the detected sources. We focus on three key parameters: flux density, angular size, and position angle. Our results show that YOLO-Chars achieves competitive detection and characterisation performance on the SKA SDC1 benchmark, demonstrating its potential as a scalable framework for next-generation radio continuum surveys.
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Instrumentation and Methods for Astrophysics · Cross-listed from astro-ph.EP

Transit Searches for Habitable-Zone Exoplanets with Artificial Intelligence

Qingtian Liu

Searching for Earth-sized planets in stellar habitable zones ultimately means finding a small number of very shallow, widely separated transits in noisy light curves. Around Sun-like stars, habitable-zone planets generally have long orbital periods, so a finite observing baseline may record only a few transits. At the same time, intrinsic stellar variability, instrumental systematics, and data gaps can obscure these weak events or produce transit-like brightness changes. This review examines recent progress in AI-assisted light-curve preprocessing, weak-signal searches, candidate vetting, and parameter inference, and considers the potential roles of pretraining and multimodal models. Taken together, the studies reviewed here show that AI has practical value in making large-scale light-curve analysis more efficient, recovering more signals at low signal-to-noise ratios in some injection tests, and reducing the number of targets requiring manual review. This review concludes that combining AI with physical modeling, statistical inference, and follow-up observations provides a practical route to improve both the discovery efficiency and the reliability of habitable-zone candidate studies.
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Instrumentation and Methods for Astrophysics · Cross-listed from physics.soc-ph

From Timbuktu to SKA: Who owns the Astronomy knowledge Africa produces?

Rhea Koch and Amare Abebe

Africa has deep and diverse traditions of astronomical knowledge, ranging from archaeological astronomy, pharaonic stellar timekeeping, and manuscript astronomy in Timbuktu and the Sahel, to ecological seasonal astronomy in southern Africa and calendrical computation in the Ethiopian tradition. These multiple epistemic traditions form part of a long intellectual history that precedes and intersects with contemporary astronomy on the continent. In the context of this long-standing intellectual heritage, an important question arises regarding the contemporary circulation of African astronomical knowledge within the global scientific system. This study therefore examines where African astronomical knowledge is produced, validated, and circulated in modern scholarly communication. Using bibliometric data from the Web of Science Core Collection, our analysis investigates publication and citation patterns in the research area Astronomy and Astrophysics between 2000 and 2025, with particular attention to the publication venues of African scholars. The findings highlight a critical paradox: while African researchers are active contributors to global astronomical discovery, the intellectual capital generated through this work is largely stored, validated, and circulated through publication systems located outside the continent. This pattern reflects broader asymmetries within global scholarly communication, where dominant publishing infrastructures shape visibility, citation impact, and authority. By applying a decolonial lens to metrics such as citation impact and ownership, the paper calls for a critical reassessment of the academic practices that sustain epistemic coloniality. It concludes that achieving scientific equity requires a strategic shift in publication choices to build and fortify a sovereign African knowledge archive.
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Instrumentation and Methods for Astrophysics

DOLPHIN (Device of Line Photometry in Nasmyth): A Switchable Multiband Photometer for the ISAS 1.3-m Telescope

Kohei Miyakawa, Hirokazu Kataza, Teruyuki Hirano et al. (+3 more)

We present the design, construction, and commissioning of DOLPHIN (Device of Line Photometry in Nasmyth), a compact instrument for switchable broad- and narrow-band photometry at the Nasmyth focus of the ISAS 1.3-m telescope. DOLPHIN was developed as a cost-conscious platform for differential measurements of selected spectral features with modest-aperture telescopes. A motorized eight-position filter wheel provides access to Johnson-Bessell B, V, and R bands and narrow-band Na D and H$\alpha$ filters. All filters share a common optical path and CMOS detector, and adjacent positions can be switched in approximately 0.8 s. The system uses commercially available components and provides an approximately 10-arcmin field of view. Laboratory characterization shows that the detector response is linear to within 0.1% below 10,000 ADU, with a conversion factor of 0.81 $e^-$/ADU, read noise of 9 $e^-$, and pixel-response non-uniformity of 0.37%. We also measure the in-system transmission profiles of all filters and identify a broader-than-specified Na D passband. Commissioning observations of HD 189733 are used to validate filter-sequence operation, image calibration, and relative photometric stability. The sequence used 1-s exposures in B, V, and R and 20-s exposures in Na D and H$\alpha$. The unbinned RMS ranges from 0.34% in Na D to 0.94% in B; after eight-point binning, the Na D/R ratio reaches 0.16%. Positive inter-band correlations that increase with bin size demonstrate removal of part of the low-frequency common-mode noise. Recovery of the known broadband transit provides an end-to-end validation of the observing and reduction system. These results establish DOLPHIN as a practical platform for differential narrow-band monitoring and define the instrumental limitations to be addressed in future observations.
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All authors Kohei Miyakawa, Hirokazu Kataza, Teruyuki Hirano, Hajime Kawahara, Shotaro Tada, Takehiko Wada

Instrumentation and Methods for Astrophysics

NestyNet. III. Symbolic Regression from Analytic Neural Surrogates

Rodrigo Ibata, Wassim Tenachi, Foivos Diakogiannis et al. (+2 more)

Many physical laws are simple only after the right representation, decomposition or internal coordinate has been found, but discovering that structure from data is combinatorially hard. This task is symbolic regression (SR), the search for closed-form expressions that fit data without assuming a fixed model class. Here we present NestyNet-SR. A neural surrogate with analytic derivatives is used to detect separability, recursively reducing multivariate problems to simpler neural atoms. These atoms are distilled into closed form by a tiered symbolic-search stack, whose final tier is a novel factorized symbolic search that separates structure from calibration. Composing candidate internal coordinates freely, it scores each coordinate by how well calibrated functions of it (e.g., polynomials, power laws, sinusoids) fit the data, so the constants of those calibrated maps, however deeply nested in the final expression, are fitted rather than searched. The method supports multi-dataset regression, automated feature discovery, and dimensional-analysis pruning. On the SRBench AI~Feynman benchmark, NestyNet-SR achieves exact symbolic recovery of all 120 noiseless equations, the first such result, and under noise a statistical audit certifies which structures survive. As a real-data vignette, given only the separate mass-model components of SPARC-survey galaxies, the algorithm discovers the baryonic acceleration coordinate, reproduces the established mass-to-light and acceleration scales and the non-unique form of the radial acceleration relation, and adds held-out-galaxy generalization, a calibrated symmetry abstention, and a posterior for the local slope of the law. Analytic derivatives thus provide a practical route from neural surrogates to interpretable closed-form empirical laws.
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All authors Rodrigo Ibata, Wassim Tenachi, Foivos Diakogiannis, Neil Ibata, Anirudh Shankar

Instrumentation and Methods for Astrophysics

NAIR-APREXIS: Enabling photonics-based instruments for long-baseline interferometry and integral-field spectroscopy

L. Labadie, R. J. Harris, K. Madhav et al. (+14 more)

The NAIR project – Novel Astronomical Instrumentation based on photonic light Reformatting – aims at advancing photonic technologies for infrared long-baseline interferometry and precision spectroscopy. The rapid development of astrophotonics over the past decade has opened new pathways for astronomical instrumentation with unprecedented capabilities. We present results from NAIR that demonstrate the potential of the ultrafast-laser inscription (ULI) technique for fabricating remapping devices for a range of applications. We developed a single-mode integrated-optics astronomical K-band beam combiner, which we successfully tested on-sky, although using only one single baseline of the CHARA Array. Across several observing campaigns, the prototype exhibited excellent stability, achieving 1% precision on the interferometric visibilities and a total on-sky throughput >40%, with an achieved limiting magnitude of K~5 using the 1-m meter telescopes of CHARA and without external fringe tracking. We are also developing an integral field unit (IFU) designed for exoplanet detection and characterisation. This is due to be tested with MagAO-X in Chile in 2027. The IFU is based upon astrophotonic fiber technologies - two-photon-polymerized (TPP) lenslets, a custom multi-core fiber, and a ULI reformatter. We discuss our efforts to achieve contrasts of 1e-3 between adjacent spaxels whilst retaining throughput of >50%. Finally, we discuss the work we are doing developing the next generation of astrophotonic technologies, including TPP micro-dispersers designed for low resolving power, high transmission applications. We achieve R~30 in a sub-mm package, showing viability for future use. These results emphasize the versatility and simplicity of integrated photonic approaches as a major advance in optical technologies for astronomical instrumentation.
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All authors L. Labadie, R. J. Harris, K. Madhav, A. Dinkelaker, K. Barjot, A. Benoît, N. J. Scott, N. Anugu, S. Mahdizadeh, V. Kutnohorsky, A. Calcines Rosario, E. Ronson, A. Magniez, R. R. Thomson, T. K. Sharma, A. V. Mayer, G. Schaefer

Instrumentation and Methods for Astrophysics · Cross-listed from physics.ins-det

Ion Irradiation of GridPix Detector at Bonn Isochronous Cyclotron

Vladislavs Plesanovs, Hemanth Manikantan, Dennis Sauerland et al. (+6 more)

The potential successor of the IXPE — the EXPO or Enhanced X-ray Polarimetry Observatory will have a new X-ray polarimeter based on GridPix technology. To certify this detector for operation within the expected radiation environment conditions, the irradiation tests were performed at the Bonn Isochronous Cyclotron at HISKPabbreviation\footnote{ stands for Helmholtz-Institut für Strahlen- und Kernphysik or Helmholz Institute for Radiation and Nuclear Physics}, University of Bonn. Two beam modes were used — proton beam at 14\,MeV and 100\,MeV $^{14}\mathrm{N}^{5+}$ ions. The aforementioned GridPix detector contains the readout ASIC, Timepix, with $256\times256$ pixel grid with a pitch of \SI{55}{\micro\meter} and covered with a protection layer. The Al grid stands on the SU8 pillars above pixels forming the amplification stage. The alignment of grid holes and silicon pixels enable primary electron detection. This paper focuses on the description and results of these testbeams. The accumulated ion rates exceed by far the expected limits without a significant deterioration in chip performance.
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All authors Vladislavs Plesanovs, Hemanth Manikantan, Dennis Sauerland, Paolo Soffitta, Carlo Lefevre, Ettore Del Monte, Jochen Kaminski, Reinhard Beck, Klaus Desch

Instrumentation and Methods for Astrophysics

EXPO: a quantum leap in fast, wide-band X-ray polarimetry for astrophysics

Paolo Soffitta, Sebastien Guillot, Ian Hutchinson et al. (+137 more)

The Enhanced X-ray Polarimetry Observatory (EXPO) is a mission concept proposed to ESA as an M8 candidate, with a prospective launch in 2041. Building on the scientific success of IXPE, EXPO is designed to overcome its two main limitations, the narrow 2-8 keV energy band and the very slow repointing time, and to enable new scientific capabilities. A wide energy band and fast repointing are essential for investigating the hard X-ray emission of magnetars and black-hole binaries, particle acceleration in supernova remnants and pulsar-wind nebulae, radiative transfer in highly magnetized plasmas, X-ray reflection in accretion flows and active galactic nuclei, and the prompt and afterglow emission of gamma-ray bursts and magnetar flares. EXPO comprises five focusing X-ray telescopes and gas photoelectric polarimeters based on the Timepix ASIC family with InGrid amplification, enabling three-dimensional track imaging and operation in the 2-35 keV band through optimized low- and medium-energy detector configurations. The mirror modules use proven electroformed nickel technology with Au-C coatings and an XMM-like focal length of 7.5 m. The polarimeters are complemented by a coded-mask Wide Field Instrument (WFI), derived from SVOM/ECLAIRs for continuous monitoring of a 2 sr field of view; a Spectral Imaging Camera (SIC), based on stacked CMOS and CdTe detectors for broadband imaging spectroscopy and accurate spectro-polarimetric decomposition; and an Instrument Control Unit (ICU) for payload management, onboard WFI image reconstruction, transient identification, and autonomous spacecraft repointing requests. These capabilities extend X-ray polarimetry into the hard X-ray domain and open a new observational window on fast transients, time-domain astrophysics, and multi-messenger astronomy.
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All authors Paolo Soffitta, Sebastien Guillot, Ian Hutchinson, Fabio Muleri, Mark Pearce, Andrea Santangelo, Daniele Spiga, Ivan Agudo, Gino Bruno Amata, Jaroslaw Bakala, Elisabetta Baracchini, Stefano Basso, Jorg Bayer, Benedikt Bergmann, Jaroslaw Borek, Enrico Bozzo, Soren Krinstian Brandt, Carl Budtz-Jorgensen, Vadim Burwitz, Stefano Cesare, Jerome Chenevez, Enrico Costa, Elisa Costantini, Vincenzo Cotroneo, Walter Cugno, Riccardo Ferrazzoli, Nicolas De Angelis, Desiree Della Monica Ferreira, Klaus Desch, Giorgio Dho, Giuseppe Di Persio, Sergio Fabiani, Davide Fiorina, Szymon Gburek, Markus Gruber, Allan Hornstrup, Jennifer Jones, Jochen Kaminski, Mozsi Kiss, Irfan Kuvvetli, Carlo Lefevre, Hannah Lerman, Honghui Liu, Pasqualino Loffredo, Niels Lund, Hemanth Manikantan, Melissa McHugh, Paul O'Brien, Stephane Paltani, Giovanni Pareschi, Stefano Piacentini, Vladislavs Plesanovs, John Rankin, Ajay Ratheesh, Selina Ringsborg Howalt Owe, Alda Rubini, Miguel Andres Sanchez Carrasco, Emanuele Scalise, Konrad R. Skup, Gianpiero Tagliaferri, Chris Tenzer, Berend Winter, Silvia Zane, Lorenzo Amati, Alessio Anitra, Maria Cristina Baglio, Thibault Barnouin, Stefano Bianchi, Fabrizio Bocchino, Markus Boettcher, Niccolo Bucciantini, Sara Capecchiacci, Fiamma Capitanio, Martina Cardillo, Eugene Churazov, Stefano Covino, Filippo D'Ammando, Laura Di Gesu, Alessandro Di Marco, Tiziana Di Salvo, Michal Dovciak, Lorenzo Ducci, Hua Feng, Giorgio Galanti, Giancarlo Ghirlanda, Vittoria Elvezia Gianolli, Andrea Gnarini, Emanuele Greco, Jeremy Heyl, Adam Ingram, Svetlana Jorstad, Philip Kaaret, Ildar Khabibullin, Fabian Kislat, Henric Krawczynski, Josefin Larsson, Ioannis Liodakis, Frederic Marin, Andrea Marinucci, Lorenzo Marra, Alan Marscher, Herman Marshall, Giorgio Matt, Marco Miceli, Riccardo Middei, Romana Mikusincova, Alexander Mushtukov, Kirpal Nandra, Lara Nava, Giuseppe Maria Oppedisano, Salvatore Orlando, Simone Pagliarella, Alessandro Papitto, Pierre-Olivier Petrucci, Oleh Petruk, Jakub Podgorny, Juri Poutanen, Arne Rau, Agata Roszanska, Felix Ryde, Vincenzo Sapienza, Patrick Slane, James Steiner, Valery Suleimanov, Jiri Svoboda, Daniele Tagliacozzo, Antonella Tarana, Fabrizio Tavecchio, Roberto Taverna, Francesco Tombesi, Sergey Tsygankov, Youli Tuo, Roberto Turolla, Francesco Ursini, Alexandra Veledina, Jacco Vink, Martin C. Weisskopf, Fei Xie, Haocheng Zhang, Menglei Zhou

Instrumentation and Methods for Astrophysics

Chang'e 7 Lunar Lander Optical Camera-Telescope: Optical Astronomy from the Moon

Quentin Andrew Parker, Partha Sarathi Pal, Junhao Chen et al. (+8 more)

We report the design and manufacture of a new, lightweight, wide-field, optical camera-telescope on board the Chang'e 7 lunar mission (launched in August 2026 and due for lunar touchdown in late November 2026). The camera is capable of static, panchromatic imagery within a $420-696~nm$ optical wavelength range. The camera was designed and built under the small lunar astronomy observation station program of the Chinese National Space Agency (CNSA) as a collaboration between the International Lunar Observatory Association of Hawaii (ILOA), the Laboratory for Space Research (LSR) of the University of Hong Kong (HKU) and the Beijing Institute of Space Mechanics and Electricity (BISME). The camera has been built to meet science goals of the mission for sustainable astronomical operation over a large range of temperatures from the Moon's south pole. We report on the design and ground based preliminary performance, together with an analysis of the camera's simulated output to indicate the range of astronomical observations possible from the lunar surface given the camera's limited sensitivity and angular resolution given the modest aperture and wide field of view.
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All authors Quentin Andrew Parker, Partha Sarathi Pal, Junhao Chen, Meng Su, SeyedAbdolreza Sadjadi, Andreas Ritter, Andy C. T. Kong, Zhengjie Tian, Haoyang Yuan, Suijian Xue, Steve Durst

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

Microwave Remote Sensing of Giant Planet Atmospheres: Considerations for Saturn and Uranus Orbiter Missions

Alex Akins and Mark Hofstadter

Microwave radiometer instruments are uniquely capable of studying volatile element abundances and heat/mass transport within the deep atmospheres of giant planets. The results of the Juno MWR experiment have challenged long-held assumptions regarding Jupiter's troposphere, and the inclusion of such an instrument on future missions to Saturn or the ice giants would similarly re-write our understanding of giant planet atmospheres. We present a high-level summary of the capabilities of microwave radiometers for the study of giant planet atmospheres, including a review of the various scientific motivations and current knowledge, concise statement of the fundamentals of radiometer remote sensing accessible at the systems-engineering level, and calculations which are of illustrative value in the design of future instruments.
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Instrumentation and Methods for Astrophysics

Amplifying the imaging power of digital sky surveys with space telescopes data and generative AI

Sai Teja Erukude and Lior Shamir

While Digital sky surveys provide excellent throughput of image data and can cover a large footprint, their imaging power is normally inferior to that of space-based telescopes. Space-based telescopes, on the other hand, provide excellent imaging power and can image the deep Universe, but cannot provide the same throughput as advanced ground-based sky surveys. Here, we utilize generative AI to elevate the quality of galaxy images taken by ground-based telescopes to the level of details enabled by space telescopes. The solution is based on the nature of galaxy shapes, allowing generative AI trained on space-based images to convert weak signal into detailed and clear galaxy images. The method allows for combining the high throughput of ground-based sky surveys with the image quality of space-based telescopes. The source code for the method is available, as well as paired training data and a catalog of 63,202 galaxy images enhanced by the proposed method. We also provide a software tool that encapsulates the entire pipeline and the custom generative AI model to generate galaxy images with enhanced quality.
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Instrumentation and Methods for Astrophysics · Cross-listed from astro-ph.EP

Physics-Informed Bayesian Optimization Warm-Starts for Sequential Convex Programming in Asteroid Surface Hopping

Baran Ekşi and Tufan Kumbasar

Surface hopping is an attractive mobility mode for small-body exploration, but designing fuel-optimal hops on asteroid 433~Eros requires solving a nonconvex optimal control problem with an irregular polyhedral gravity field, thrust–mass coupling, and collision-avoidance constraints. We show that a physics-informed Bayesian Optimization (BO) warm-start—a Gaussian-process search over a single Bézier control point that requires no offline training—provides a more reliable initialization for Sequential Convex Programming (SCP) than the standard straight-line guess. The straight chord penetrates the asteroid on every inter-site transfer considered here and degrades convergence. The physics-informed BO reference feeds an SCP stage in which a log-mass change of variables convexifies the thrust–mass coupling and nearest-facet half-spaces enforce collision avoidance, and an automated Pareto time-of-flight sweep selects fuel-priority solutions without introducing bilinear terms. Applied to all 20 ordered transfers among five representative surface sites and validated under 10 random seeds, the framework tracks every trajectory to meter-level terminal accuracy in closed-loop Monte Carlo simulation, completes a five-site tour for one fifth of the propellant budget, and reduces mean $\Delta V$ by roughly one third relative to an idealized two-impulse ballistic trajectory estimate. A straight-line ablation credits the warm-start with cutting the mean SCP iteration count from 8.8 to 5.9 and removing the one convergence failure. A target-perturbation analysis further shows that the solutions vary smoothly with the landing target, with no jumps between local basins.
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Instrumentation and Methods for Astrophysics · Cross-listed from gr-qc

Bayesian P-spline recovery of stochastic gravitational-wave backgrounds in LISA

Nazeela Aimen, Patricio Maturana-Russel, Avi Vajpeyi et al. (+2 more)

The detection of a stochastic gravitational-wave background (SGWB) is a primary science objective for the Laser Interferometer Space Antenna (LISA). However, extracting these signals is difficult because both the signal and the instrumental noise are stochastic and overlapping in the millihertz band. In this work, we present a Bayesian framework for the joint estimation of LISA noise and SGWB signals. Our approach models the LISA instrumental noise using flexible log-penalized splines, employing a roughness penalty to prevent overfitting while maintaining computational efficiency. For the SGWB, we compare a power-law model with a spline-based model and study how the choice of signal model and noise prior affects signal recovery and detection. Using simulated LISA data, we find that the power-law model gives tighter estimates when the signal follows the assumed shape. However, it fails to recover a localized spectral feature that is not described by a power law, causing the signal to be absorbed by the instrumental-noise spline. The fully spline-based model is less restrictive and successfully recovers such features. We also find that stronger prior information about the test-mass noise helps reduce the degeneracy between the noise and SGWB models at low frequencies, improving signal detection. These results reflect a single trade-off: added model flexibility reduces sensitivity when the assumed signal shape is correct, and prevents bias when it is not.
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All authors Nazeela Aimen, Patricio Maturana-Russel, Avi Vajpeyi, Nelson Christensen, Renate Meyer

Thursday 20 August

Instrumentation and Methods for Astrophysics · Cross-listed from physics.hist-ph

Jodrell Bank and the British Astronomical Association: The Making of a Generation of Scientists

Jeremy Shears

The discovery of radar echoes from meteor trains at Jodrell Bank in 1945 marked the beginning of a new era in meteor astronomy and laid the foundations for the subsequent development of radio astronomy. This paper examines the close relationship between Bernard Lovell's emerging research group at Jodrell Bank and the British Astronomical Association (BAA) during the formative years, 1946-1951. It explores the contributions of the individuals who connected these two communities. Particular attention is given to the lives and scientific careers of Michael Ovenden, Gerald Hawkins, John Clegg, John Davies, Victor Hughes and Mary Almond, all of whom were BAA members. Their later achievements demonstrate the remarkable talents of this generation of scientists, whose work extended across radio astronomy, planetary science, palaeomagnetism, archaeomagnetism and computer science.
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Instrumentation and Methods for Astrophysics · Cross-listed from cs.PL

Portability of Fortran's 'do concurrent' on GPUs II

Ronald M. Caplan, Miko M. Stulajter, Jon A. Linker et al. (+6 more)

There continues to be growing interest in using standard language constructs for parallel and accelerated HPC computing, avoiding the need for (sometimes vendor-specific) external APIs. For Fortran applications, language features such as 'do concurrent' loops open the door for compilers to implement multi-threaded, GPU-accelerated, and even distributed multi-node code with only the standard language. Here, we explore the current status of using 'do concurrent' for GPU-accelerated Fortran applications across three major GPU vendors (NVIDIA, AMD, and Intel). Using a production application, we test their current capabilities, showing where the standard language alone can be used, and where augmenting the code with a directive-based API (e.g., OpenMP) is still desirable or required. Multi-GPU tests are performed with GPU-aware MPI libraries. We find that the three GPU vendors can now GPU-accelerate pure Fortran (zero directives), but that manual data movement directives can help with performance and compatibility. The results show that there is rapid advancement towards making GPU-accelerated scientific HPC code performance portable using the Fortran standard language.
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All authors Ronald M. Caplan, Miko M. Stulajter, Jon A. Linker, Jeff Larkin, Nikolaos Tselepidis, Harald Servat, Shiquan Su, Giacomo Capodaglio, Johanna Potyka

Instrumentation and Methods for Astrophysics

High-contrast aperture masking interferometry: detecting companions within the diffraction limit

Benjamin Calvin, Michael Fitzgerald and Jessica Castellanos

The pursuit of the direct discovery and characterization of Earth-like exoplanets has motivated high contrast imaging surveys using coronagraphs with narrow inner working angles. Traditional imaging methods, however, are limited by the size of the on-axis PSF and typically only detect companions at angular separations of > 2$\lambda$/D. Meanwhile, non-redundant masking (NRM) techniques have been used with single-aperture telescopes to interferometrically resolve astrophysical features at angular scales within the diffraction limit, but NRM interferometry faces sensitivity issues for high-contrast objects. In this project, we investigate utilizing high contrast coronagraphy in conjunction with NRM interferometry. We conduct a preliminary investigation of this combined architecture with the goal of determining the potential bounds of performance and discovery space for high-contrast targets within the inner working angle of traditional high-contrast imaging. We predict an improvement in the achievable contrast for photon-limited observations by combining the techniques, and we also develop estimates for wavefront stability requirements for the system.
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Instrumentation and Methods for Astrophysics · Cross-listed from astro-ph.EP

Leveraging Impact Parameter to Mitigate the Transit Light Source Effect: Early Insights from TRAPPIST-1

Ana Glidden, Alexander I. Shapiro, Sara Seager et al. (+19 more)

Stellar activity complicates exoplanet transmission spectra, particularly for smaller planets around M dwarfs with JWST. The transit light source (TLS) effect, the imprinting of spectral differences between the average stellar disk and the occulted transit chord onto the transmission spectrum, makes it challenging to directly use the out-of-transit spectrum to correct for stellar contamination. Theory and observations suggest that spots may concentrate towards higher latitudes when the Coriolis force is substantial relative to buoyancy, leaving the equatorial region relatively quiet. Here, we evaluate how the latitudinal distribution of active regions shapes the strength of the TLS effect for planets spanning a range of impact parameters ($b$), using TRAPPIST-1 as a testbed. We first construct a fiducial model to illustrate two distribution regimes. With our model, the moderate-$b$ outer TRAPPIST-1 planets (f, g, h) occult a more typical region of the stellar disk than the inner planets and are thereby less affected by the TLS effect, though their bias may vary more from visit-to-visit as these active regions evolve with time. More generally, our results imply an impact parameter "sweet spot" for atmospheric characterization, independent of the sign of the active region temperature contrast, whose location depends on the distribution of active regions. The distribution may be revealed by transit residuals as multiple planets probe different latitudes, while longitudes are sampled in time, such that the variance and frequency of the correlated scatter could constrain active-region filling factors, sizes, and separations.
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All authors Ana Glidden, Alexander I. Shapiro, Sara Seager, Nadiia Kostogryz, Valeriy Vasilyev, Roeland P. van der Marel, Julien de Wit, Benjamin V. Rackham, Prajwal Niraula, Natalie H. Allen, Jingcheng Huang, Nikole K. Lewis, Zifan Lin, Jacob Lustig-Yaeger, Ryan J. MacDonald, Brett M. Morris, Elijah Mullens, Kevin B. Stevenson, Jeff A. Valenti, Daniel Valentine, Hannah R. Wakeford, C. Matt Mountain

Instrumentation and Methods for Astrophysics

A Multi-instrument Generalized Lomb-Scargle Periodogram Implementation

Giulia Martos, Néstor Espinoza and Jorge Meléndez

We present an implementation of the well-known and broadly used Generalized Lomb-Scargle Periodogram (GLS) which simultaneously takes into account individual offsets introduced in the data by different instruments: a "multi-instrument" GLS periodogram. While the algorithm itself is not new, the simple closed form implementation we provide, to our knowledge, is. We showcase an application of our multi-instrument GLS on radial-velocity data of the hot Jupiter TOI-481 b, whose period is recovered with a higher significance compared to the standard GLS approach. The code is available on GitHub.
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