arXiv subjects

Anton Pomazan

Publications and source records attributed to Anton Pomazan.

3 recordsLinked to original sources

arXiv2026

AstroSkyFlow: an astronomical sky image flow simulator for time domain survey validation and machine learning

Modern time-domain optical surveys produce massive data volumes that require robust, high-fidelity simulated datasets for developing and validating automated pipelines and machine-learning models. We present AstroSkyFlow, a modular sky-image simulator that generates on-demand, time-dependent flux variations and models the full observing stack, from celestial sources and atmospheric effects to sensor response. Given a simulated observing schedule, AstroSkyFlow produces multi-epoch, time-series images with realistic noise and variability. Compared to real observational data, AstroSkyFlow reproduces noise characteristics and point spread function properties more accurately than the widely used SkyMaker simulator. In addition, AstroSkyFlow successfully recovers injected photometric and motion signals, such as exoplanet transits and asteroid trails. AstroSkyFlow enables the generation of labeled, high-fidelity datasets essential for training machine-learning pipelines and conducting rigorous injection-recovery tests for analysis pipelines for next-generation time-domain surveys.

astro-ph.IM↗

arXiv2026

Photometry and physical characterization of near-Earth asteroid 2025 FA22 from one apparition

We present comprehensive photometric characterisation of 2025 FA$_{22}$, a Potentially Hazardous Asteroid (PHA) discovered on 29 March 2025 and observed during the seventh International Asteroid Warning Network (IAWN) coordinated campaign. The asteroid's close approach at 2 lunar distances on 18 September 2025 provided an opportunity for rapid physical characterisation in a simulated virtual impactor scenario. Photometric observations were conducted from 17 September to 1 October 2025, during which 2025 FA$_{22}$ traversed a $150^{\circ}$ arc and spanned solar phase angles from $\sim20^{\circ}$ to $\sim70^{\circ}$. This geometry enabled detailed physical characterisation, including determination of the spin axis and shape. Convex inversion yields a sidereal rotation period of $P_{\mathrm{sid}} = 13.07366 \pm 0.00076$ h and a spin axis at ecliptic coordinates $(λ, β) = (246^{\circ} \pm 9^{\circ}, 60^{\circ} \pm 9^{\circ})$. The absolute magnitude was derived as $H_{\mathrm{V}} = 21.39^{+0.07}_{-0.08}$ mag ($G_1 = 0.8228$, $G_2 = 0.0194$), with colour indices $B-V = 0.71 \pm 0.05$ mag, $V-R = 0.39 \pm 0.03$ mag, and $R-I = 0.39 \pm 0.04$ mag, consistent with X-complex classification in the Bus--DeMeo taxonomy. Assuming a geometric albedo of $p_v = 0.15^{+0.05}_{-0.04}$, representative of the moderate-albedo X-complex asteroids, we estimate $D_{\mathrm{eff}} = 181^{+31}_{-25}$ m, consistent with "China Compound Eye" radar dimensions of ${\sim}100 \times 320$ m ($D_{\mathrm{eff}} \sim 186$ m), which also reveal a contact-binary morphology consistent with the axis ratios $a:b:c \sim 2.68:1.96:1.00$ derived from our photometric shape model. The bilobate morphology is consistent with YORP-driven spin-up and deformation during a previous YORP cycle, with the current slow rotation possibly explained by internal reconfiguration or tidal braking during close Earth encounters.

astro-ph.EP↗

arXiv2025

Search for Past Stellar Encounters and the Origin of 3I/ATLAS

3I/ATLAS, the third discovered interstellar object, has a heliocentric speed of 58 km/s and exhibits cometary activity. To constrain the origin of 3I/ATLAS and its past dynamical evolution, we propagate the orbits of 3I/ATLAS and nearby stars to search for stellar encounters. Integrating orbits in the Galactic potential and propagating the astrometric and radial-velocity uncertainties of 30 million Gaia stars, we identify 25 encounters with median encounter distances less than 1 pc. However, because the encounter speeds between 3I/ATLAS and each encounter exceed 20 km/s, none is a plausible host under common ejection mechanisms. We infer stellar masses for most stars and quantify the gravitational perturbations exerted by each individual star or each binary system on 3I/ATLAS. The strongest gravitational scattering perturber is a wide M-dwarf binary. Among all past encounters, the binary's barycenter and 3I/ATLAS reach the small encounter distance of 0.242 pc and the encounter speed of 28.39 km/s,1.64 Myr ago. We further demonstrate that the cumulative influence of the stellar encounters on both the speed and direction of 3I/ATLAS is weak. Based on the present kinematics of 3I/ATLAS to assess its origin, we find that a thin-disk origin is strongly favored, because the thin disk both exhibits a velocity distribution closely matching that of 3I/ATLAS and provides the dominant local number density of stars.

astro-ph.SR↗