BV photometry of the ultracompact binary star GP Com

We present optical B and V band photometry of GP Com - an ultracompact binary (orbital period 47 minutes) consisting of an accreting white dwarf and helium secondarycomponent. Our data set contains 7.7 hours observations in V band with the 2.0m telescope and 2.9 hours simultaneous observations in B and V bands with the 1.5m telescope of the Rozhen National Astronomical Obsevatory, Bulgaria. The observations cover about 13 orbital periods.本文报道了GP Com的光学B波段与V波段测光数据——GP Com是一颗轨道周期为47分钟的极短周期双星系统，由一颗正在吸积的白矮星与氦星次伴星构成。本数据集包含使用2.0米望远镜在V波段开展的7.7小时观测数据，以及使用保加利亚罗岑国家天文台（Rozhen National Astronomical Observatory）1.5米望远镜同步获取的2.9小时B波段与V波段观测数据。此次观测覆盖约13个轨道周期。