Astrokit -- an Efficient Program for High-Precision Differential CCD Photometry and Search for Variable Stars

TL;DR

Astrokit is a software tool designed for high-precision differential CCD photometry, enabling efficient detection of variable stars and exoplanet transits in large astronomical datasets.

Contribution

The paper introduces Astrokit, a novel software that automates high-precision photometry and variable star detection using robust statistical methods, suitable for large-scale surveys.

Findings

Successfully applied to sky survey data in Cygnus

Detected low-amplitude variable stars and exoplanet transits

Achieved high-precision photometry for thousands of stars

Abstract

Having a need to perform differential photometry for tens of thousands stars in a several square degrees field, we developed Astrokit program. The software corrects the star brightness variations caused by variations of atmospheric transparency: to this end, the program selects for each star an individual ensemble of reference stars having similar magnitudes and positions in the frame. With ten or more reference stars in the ensemble, the differences between their spectral types and the spectral type of the object studied become unimportant. Astrokit searches for variable stars using Robust Median Statistics criterion, which allows candidate variables to be selected more efficiently than by analyzing the standard deviation of star magnitudes. The software allows very precise automatic analysis of long inhomogeneous sets of photometric observations of a large number of objects to be performed, making it possible to find "hot Jupiter" type exoplanet transits and low-amplitude variables. We describe the algorithm of the program and the results of its application to reduce the data of the photometric sky survey in Cygnus as well as observations of the open cluster NGC188 and the transit of the exoplanet WASP-11 b / HAT-P-10 b, performed with the MASTER-II-URAL telescope of the Kourovka Astronomical Observatory of the Ural Federal University.