Experimental Astronomy最新文献

{"title":"Correction to: Kosmiko: from CMOS imaging sensors to pixel-calibrated particle instruments","authors":"Frédéric Wrobel, Juliette Wrobel, Tadec Maraine, Jérôme Boch, Clément Risso, Luigi Dilillo, Frédéric Saigné","doi":"10.1007/s10686-026-10085-5","DOIUrl":"10.1007/s10686-026-10085-5","url":null,"abstract":"","PeriodicalId":551,"journal":{"name":"Experimental Astronomy","volume":"62 3","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149189743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Kosmiko: from CMOS imaging sensors to pixel-calibrated particle instruments","authors":"Frédéric Wrobel,&nbsp;Juliette Wrobel,&nbsp;Tadec Maraine,&nbsp;Jérôme Boch,&nbsp;Clément Risso,&nbsp;Luigi Dilillo,&nbsp;Frédéric Saigné","doi":"10.1007/s10686-026-10081-9","DOIUrl":"10.1007/s10686-026-10081-9","url":null,"abstract":"<div><p>We present a low-cost, reproducible methodology for detecting ionizing-event candidates in the natural radiation environment by using CMOS active-pixel sensors operated in darkness. The detector platform, called Kosmiko, is based on a Raspberry Pi 5 that controls simultaneously two Sony IMX477 camera modules in raw acquisition mode. Each run consists of a calibration step followed by continuous image acquisition. Candidate events are identified online by comparing each pixel intensity to its intrinsic threshold derived from calibration stage. Pixels that have intensities above their threshold are stored, whereas the others are discarded, which strongly reduces the data volume and enables long-duration acquisitions. The method includes the identification and filtering of hot, noisy and recurrent pixels, together with camera-health indicators based on dark-level statistics, noise distributions and percentiles. Offline analysis then provides event-rate observables, including frame-of-interest rate, cluster rate, intensity distributions, track-like topology indicators and saturated-pixel occurrence. The goal is not to identify individual particle species, but to provide a documented and deployable methodology for comparing ionizing-event rates under different conditions in the natural radiation environment. The complete hardware, software workflow and data products are described to ease reproducibility and future network deployment. Observations about components of the camera and about the local environment are also discussed.</p></div>","PeriodicalId":551,"journal":{"name":"Experimental Astronomy","volume":"62 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149034789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Efficient deep learning for single imaging cherenkov telescope event classification: improving over standard ML with minimal compute cost","authors":"Chinmay Borwankar,&nbsp;Praduman Pandey,&nbsp;Mradul Sharma,&nbsp;Kuldeep Yadav","doi":"10.1007/s10686-026-10080-w","DOIUrl":"10.1007/s10686-026-10080-w","url":null,"abstract":"<div><p>Gamma–hadron separation is a critical task in the analysis of data from imaging atmospheric Cherenkov telescopes (IACTs). The current standard approach in the field typically employs ensemble learning methods, such as random forests, trained on Hillas parameters of events derived from image moments. In this work, we present a lightweight deep learning model based on a simple two-layer convolutional neural network (CNN) followed by attention pooling, designed specifically for single-telescope IACT image classification. The attention pooling mechanism uses query vectors generated from Hillas parameters, providing global event-level context to guide feature aggregation from the convolution feature maps. Unlike several recent deep learning approaches that apply extensive image preprocessing—such as Gaussian kernel smoothing, oversampling to square grids, or custom hexagonal convolution kernels—our method directly uses a <span>(varvec{textrm{25} times textrm{25}})</span> pixel matrix extracted around the cleaned image, fed to the network without further spatial transformations. Comparison of the classification performance of proposed model with that of a standard random forest model on simulated IACT data, shows enhanced background suppression for the CNN model at all levels of signal acceptance. Application of the novel method to the real MACE data collected during observations of Crab nebula shows up to 25 % increase in detection significance relative to standard method. The deep learning model can be trained on a 16-core CPU machine in <span>(sim )</span> 90 minutes, and achieves an inference rate of about 2.96 kHz on CPU, enabling rapid deployment without the need for GPUs. While the scope of the present work is restricted to the single-telescope case, the results demonstrate that lightweight architectures with minimal pre-processing can provide a practical and effective alternative to standard machine learning methods by offering higher classification performance, together with the computational efficiency and simplicity needed for large-scale analyses.</p></div>","PeriodicalId":551,"journal":{"name":"Experimental Astronomy","volume":"62 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148986628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Solar X-ray Polarization Detector (SXPD): a solar flare detector based on GMPD","authors":"Haoran Liu,&nbsp;Hongbang Liu,&nbsp;Difan Yi,&nbsp;Tianyi Xiong,&nbsp;Huanbo Feng,&nbsp;Junhua Feng,&nbsp;Zuke Feng,&nbsp;Fei Xie,&nbsp;Huijun Hu,&nbsp;Enwei Liang","doi":"10.1007/s10686-026-10079-3","DOIUrl":"10.1007/s10686-026-10079-3","url":null,"abstract":"<div><p>We present the design of a solar flare detector, the Solar X-ray Polarization Detector (SXPD), based on the Gas Microchannel Plate Pixel Detector (GMPD). The primary scientific objectives are to measure the polarization state and spectrum of individual solar flares in the soft X-ray band, where polarized bremsstrahlung radiation is expected to be produced by high-energy electron beams accelerated within the solar magnetic field and plasma. The SXPD comprises two key modules: a Pinhole Imaging Tube and a GMPD module. This paper provides a detailed description of the structural design and performance of the SXPD. With its imaging capability, the SXPD can resolve individual solar flares in the soft X-ray energy range with an angular resolution of 1.5 arcsec. Based on conservative estimates, over typical durations, the detector can achieve an MDP of 15.0% - 23.0% for B-class flares, 8.0% - 12.0% for C-class flares, 2.0% - 2.3% for M-class flares, and 0.6% - 1.0% for X-class flares.</p></div>","PeriodicalId":551,"journal":{"name":"Experimental Astronomy","volume":"62 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148986206","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation on mean temperature fluctuation of the cosmic microwave background using blackbody radiation inversion","authors":"Amal Pushp,&nbsp;Somita Dhal,&nbsp;Koustav Konar,&nbsp;R. K. Paul","doi":"10.1007/s10686-026-10078-4","DOIUrl":"10.1007/s10686-026-10078-4","url":null,"abstract":"<div><p>This work analyzes the COBE/FIRAS dataset to estimate the Cosmic Microwave Background (CMB) temperature and its associated uncertainty using the Blackbody Radiation Inversion (BRI) method. In particular, we investigate fluctuations in the mean CMB temperature and evaluate key statistical quantities, including the uncertainty and the second-order moment of the temperature distribution. We find the ensemble-averaged mean monopole temperature at <span>(varvec{2.729 pm 0.0195})</span> K. While the temperature distribution largely resembles a Gaussian profile, the wings show minor deviations resulting in an excess kurtosis of -0.03. Furthermore, analysis in frequency subsets reveals the signatures of non-Gaussianity to be frequency-dependent. It demonstrates that the BRI method is a reliable tool for precision thermometry and presents a broader application in probing the thermal characteristics of the early universe.</p></div>","PeriodicalId":551,"journal":{"name":"Experimental Astronomy","volume":"62 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148927718","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Polarimetric decomposition-based analysis of Chandrayaan-2 L-band DFSAR data for potential water ice detection in lunar polar regions","authors":"Mulkala Saritha,&nbsp;Anjaneyulu Lokam,&nbsp;Kiran Dasari","doi":"10.1007/s10686-026-10077-5","DOIUrl":"10.1007/s10686-026-10077-5","url":null,"abstract":"<div><p>The DFSAR (Dual-Frequency Synthetic Aperture Radar) onboard the Chandrayaan-2 spacecraft, launched on July 22, 2019, represents a significant advance in radar-based exploration of solid celestial bodies. Chandrayaan-2 is equipped with an array of sophisticated sensors, including the DFSAR, which operates in both the L-band and the S-band in Fully Polarimetric (FP) and compact polarimetric (CP) modes. In this study, we utilize L-band Synthetic Aperture Radar (SAR) data to analyze the lunar regolith. The L-band has superior penetration capabilities, allowing for more effective retrieval of subsurface parameters compared to previous S-band SAR missions. By using L-band in Fully Polarimetric (FP) mode, we can effectively characterize the lunar surface. This technology enables detailed polarimetric analysis of the lunar surface, particularly in the challenging Permanently Shadowed Regions (PSRs) at the lunar poles. These PSRs serve as cold traps for water molecules and are ideal locations for exploring water ice. DFSAR, SLI data is imported, and pre-processing is carried out after generating the scattering matrix. Multilooking is performed with a factor of 38. Refined Lee filter [5x5] window size is applied after coherency matrix generation to remove the speckle in the data, and also multiple decomposition techniques are employed, including the <span>(H/A/bar{alpha })</span> decomposition (based on eigenvalue-eigenvector analysis) and the Yamaguchi four-component decomposition model (based on double-bounce, surface, and volume scattering), which effectively characterize the variations in surface roughness, material composition, and topography of the crater’s inner and outer walls. This study focuses on the polar and non-polar regions (Hermite-A, Peary, Gardner, and Korolev X crater regions), utilizing DFSAR data to conduct a comprehensive polarimetric analysis aimed at identifying the potential presence of water ice deposits. The results reveal the dominance of volume scattering within the walls of the crater, which is verified across all decomposition methods. Circular Polarization Ratio (CPR) analysis further demonstrates a pronounced difference between the interior and exterior regions, with the interior values suggesting rough textures and a higher probability of water ice presence. This aligns with prior studies that associate elevated CPR values and volume scattering with ice deposits in the lunar Polar Regions. To validate the SAR-based analysis, high-resolution lunar surface images captured by the Navigation camera onboard Pragyan Rover at the Chandrayaan-3 landing site were examined. The change in surface roughness before and after landing was reflected in scattering powers, confirming changes in the lunar terrain.</p></div>","PeriodicalId":551,"journal":{"name":"Experimental Astronomy","volume":"62 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10686-026-10077-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148927314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Long-term dynamics and machine learning-based mapping of night sky brightness: snowglow, urbanization, and topography effects at major astronomical observatories in Türkiye","authors":"Kazım Kaba,&nbsp;Sima Aydın,&nbsp;Rabia Beyza Türkmen,&nbsp;Fethullah Polat,&nbsp;Funda Aksoy,&nbsp;İlham Nasıroğlu,&nbsp;Cahit Yeşilyaprak,&nbsp;H. Mustafa Kandırmaz","doi":"10.1007/s10686-026-10076-6","DOIUrl":"10.1007/s10686-026-10076-6","url":null,"abstract":"<div><p>Anthropogenic alterations to the nocturnal environment pose a fundamental effect to the optical viability of ground-based astronomical observatories. This study presents a comprehensive spatiotemporal assessment of light pollution dynamics affecting Türkiye’s premier research facilities, the Eastern Anatolia Observatory (DAG) in Erzurum and the TÜBİTAK National Observatory (TUG) in Antalya within the Türkiye National Observatories, situated in contrasting highland and coastal topographies. To bridge the scale gap between the remote sensing and ground-based site testing, we developed a traditional regression and a hybrid machine learning regression Kriging framework. These approaches synthesized high-resolution, high-quality radiance data from the Suomi-NPP VIIRS with extensive in-situ sky quality meter measurements. A rigorous methodological comparison revealed that traditional geostatistical methods (Ordinary/Universal Kriging) suffered from smoothing effects and overfitting in complex terrains. Furthermore, while advanced algorithms like support vector regression achieved high statistical scores, they produced physically implausible extrapolations in data-sparse regions. In contrast, the proposed random forest regression Kriging model proved superior, achieving robust validation accuracy (R² = 0.74 and 0.80) while maintaining strict physical consistency with natural sky brightness limits. Temporal analyses in the study demonstrated that the high-altitude Erzurum plateau exhibited a distinct seasonal cycle with the snowglow effect, where surface snow cover increased human-induced skyglow by &gt; 1.5 times. In contrast, the Antalya coast exhibited a monotonous deterioration independent of seasonality, triggered by rapid tourism-oriented urbanization.</p></div>","PeriodicalId":551,"journal":{"name":"Experimental Astronomy","volume":"62 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148926887","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ultra-high-resolution astronomy with the solar gravitational lens","authors":"Slava G. Turyshev","doi":"10.1007/s10686-026-10073-9","DOIUrl":"10.1007/s10686-026-10073-9","url":null,"abstract":"<div><p>The solar gravitational lens (SGL) is a target-specific physical-optics observatory: the Sun supplies the dominant wave-optical element, while a spacecraft or formation in the focal region supplies occultation, calibrated annular photometry, image-plane sampling, metrology, and inverse reconstruction. We develop a quantitative observability framework for representative non-exoplanet SGL astronomy, not an end-to-end mission validation. Target viability is controlled by the source-to-image mapping <span>(varvec{rho }=-(z/z_0)varvec{xi })</span>, image-plane diameter <span>(D_textrm{img}=zTheta)</span>, raster pitch <span>(Delta _textrm{img}=D_textrm{img}/n)</span>, finite-source gain scale <span>(mu _textrm{ext}D_textrm{img}simeq 4b)</span>, source-to-background ratio, temporal coherence, PSF knowledge, calibration covariance, metrology, and focal-line access. We distinguish the full vector Poisson measurement operator from the stationary aperture-averaged scalar convolution used for controlled benchmarks. Four analytic scenes are propagated and reconstructed: a solar analog and magnetic white dwarf at <span>(10,textrm{pc})</span>, an M87*-scale compact millimeter ring/jet source, and a bright <span>(0.1,textrm{AU})</span> protoplanetary subfield at <span>(140,textrm{pc})</span>. Under stated kernel-mismatch, background, calibration-floor, support-mask, sampling, and regularization assumptions, and an imposed effective convolved-raster information floor <span>(textrm{SNR}_{C})</span>, the scalar reconstructions give <span>(textrm{SSIM}=0.993)</span>, 0.918, 0.973, and 0.923. These metrics quantify scalar inverse conditioning, not delivered flight performance; truth-referenced <span>(textrm{FRC}_{50})</span>, support-leakage, and <span>(textrm{SSIM})</span>-vs-<span>(textrm{SNR}_{C})</span> diagnostics make the dependence on the assumed information floor explicit. Many self-luminous compact targets are not photon-starved relative to a reflected-light exo-Earth reference, so the dominant requirements become calibrated ring extraction, solar/coronal subtraction, detector dynamic range, PSF knowledge, cadence, spectroscopy, metrology, scan overhead, and focal-line access. Within the assumptions of this study, the most promising candidate cases are white-dwarf surface and magnetic mapping, nearby stellar surfaces, compact AGN/black-hole structure with dedicated long-wavelength instrumentation, velocity-resolved broad-line-region mapping, selected planet-forming subfields. A separate highest-priority enabling program is SGL transfer-function characterization: measuring the solar-multipole, plasma, extended-Sun, instrumental components of the SGL response needed to make such imaging scientifically interpretable.</p></div>","PeriodicalId":551,"journal":{"name":"Experimental Astronomy","volume":"62 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148926589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Correction of the influence of rolling shutter detectors on determining the velocity of meteors from video recordings","authors":"Lukáš Shrbený,&nbsp;Jiří Borovička,&nbsp;Pavel Spurný,&nbsp;Jan Mánek,&nbsp;Jan Fuchs","doi":"10.1007/s10686-026-10075-7","DOIUrl":"10.1007/s10686-026-10075-7","url":null,"abstract":"<div><p>Modern video cameras use either global or rolling shutter to create individual video frames. In case of global shutter, the whole frames are exposed and read out at the same time. In case of rolling shutter, the exposure and readout proceed sequentially line by line. Such cameras are now commonly used for meteor observations. It is then necessary to perform a correction for this type of image reading in order to correctly and accurately determine the velocity of recorded meteors. We provide here the correct procedure, which replaces the previous assumption <span>(P=1/F)</span> with a measured value of <i>P</i>. The correction must include the value of the rolling period of the sensor, which is generally not provided in camera specifications. We discuss five methods of determining the rolling period experimentally. The most accurate method uses the New EXposure Timing Analyser (NEXTA) of [1]. We list rolling periods measured for several cameras.</p></div>","PeriodicalId":551,"journal":{"name":"Experimental Astronomy","volume":"62 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148838198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multispectral characterization of urban lighting transitions and atmospheric scattering impacts on dark-sky preserves using SDGSAT-1 glimmer imagery","authors":"Kazım Kaba,&nbsp;Sima Aydın,&nbsp;Rabia Beyza Türkmen,&nbsp;Fethullah Polat,&nbsp;Funda Aksoy,&nbsp;İlham Nasıroğlu,&nbsp;Cahit Yeşilyaprak,&nbsp;H. Mustafa Kandırmaz","doi":"10.1007/s10686-026-10074-8","DOIUrl":"10.1007/s10686-026-10074-8","url":null,"abstract":"<div><p>This study presents a comprehensive framework for the radiometric restoration, multispectral classification, and environmental impact assessment of urban lighting using Sustainable Development Science Satellite (SDGSAT-1) Glimmer Imager data. Focusing on the TÜBİTAK National Observatory (TUG) in Antalya and the Eastern Anatolia Observatory (DAG) in Erzurum within the Türkiye National Observatories in Türkiye, we developed a radiance-based restoration workflow that strictly preserves faint stray light signals, validated by a strong log-linear correlation (<i>r</i> ≈ − 0.94) with in-situ Sky Quality Meter (SQM) measurements. Discrete classification revealed a marked “spectral shift” in Antalya, where white light emitting diodes (LED) coverage reached 9.2% driven by commercial zones, whereas Erzurum retained a spectrally homogeneous high-pressure sodium infrastructure (&gt; 77%). Crucially, a physically-based atmospheric scattering risk model uncovered a counter-intuitive phenomenon: despite Antalya’s larger footprint, Erzurum yielded a significantly higher total risk score (76,069 vs. 56,947). This paradox is resolved by distinguishing between geometric threats, driven by the sheer proximity of Erzurum’s core to DAG site, and spectral threats, caused by the high scattering efficiency of Antalya’s distant coastal LEDs. These findings demonstrate that SDGSAT-1 provides actionable evidence for differentiated conservation strategies, specifically, strict shielding for intensity-driven risks and spectral filtering for spectrum-driven threats.</p></div>","PeriodicalId":551,"journal":{"name":"Experimental Astronomy","volume":"62 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148810958","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}