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

摘要

Having a need to perform differential photometry for tens of thousands starsin a several square degrees field, we developed Astrokit program. The softwarecorrects the star brightness variations caused by variations of atmospherictransparency: to this end, the program selects for each star an individualensemble of reference stars having similar magnitudes and positions in theframe. With ten or more reference stars in the ensemble, the differencesbetween their spectral types and the spectral type of the object studied becomeunimportant. Astrokit searches for variable stars using Robust MedianStatistics criterion, which allows candidate variables to be selected moreefficiently than by analyzing the standard deviation of star magnitudes. Thesoftware allows very precise automatic analysis of long inhomogeneous sets ofphotometric observations of a large number of objects to be performed, makingit possible to find "hot Jupiter" type exoplanet transits and low-amplitudevariables. We describe the algorithm of the program and the results of itsapplication to reduce the data of the photometric sky survey in Cygnus as wellas observations of the open cluster NGC188 and the transit of the exoplanetWASP-11 b / HAT-P-10 b, performed with the MASTER-II-URAL telescope of theKourovka Astronomical Observatory of the Ural Federal University.