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arXiv · 2607.27414

PhoPS: An automated photometric pipeline for survey-era astronomy

Orhan Erece·Yucel Kilic
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Abstract

Modern astronomical surveys produce large volumes of imaging data together with highly accurate astrometric and photometric reference catalogues, creating a need for automated, robust, and instrument-independent reduction pipelines. We present PhoPS (Photometry and Astrometry of Point Sources), an open-source Python pipeline for fully automated astrometric calibration and photometric reduction of stellar and moving Solar System targets. PhoPS dynamically generates local Gaia DR3 astrometric index files propagated to the observation epoch, eliminating the need for pre-installed index collections while improving astrometric accuracy. Photometric calibration uses a field-dependent zero-point model based on Random Sample Consensus (RANSAC) linear regression to account for spatial systematics such as vignetting and detector non-uniformities. Astrometric performance was evaluated using 141672 matched measurements from 840 images obtained with the 1 m TUG100 telescope. Epoch propagation reduced the clipped N-weighted total RMS residual from 0.284 arcsec to 0.241 arcsec, a 15.0% improvement. The photometric uncertainty model was validated using 203 reference stars and 92980 measurements. Normalized residuals are centered near zero, but their widths are magnitude dependent, with sigma values of 2.069 for bright stars (10 <= G < 13), 1.129 for intermediate-brightness stars (13 <= G < 16), and 0.698 for faint stars (16 <= G < 18), indicating underestimated uncertainties for the brightest stars and conservative uncertainties for the faintest stars. PhoPS provides a lightweight, cross-platform solution for automated astronomical image reduction and is well suited to asteroid light-curve analysis, stellar variability studies, and the diagnosis of observational systematics.

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Orhan Erece, Yucel Kilic. 2026-07-29. PhoPS: An automated photometric pipeline for survey-era astronomy. https://arxiv.org/abs/2607.27414

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