The correction of diurnal effects on CSTAR photometry

In January, 2008 the Chinese Small Telescope ARray (CSTAR) was successfully deployed at Dome A, Antarctica. Because CSTAR consists of four static 14.5 cm telescopes pointing at the same 4.5 ° × 4.5 ° field around the south celestial pole, diurnal motion can be seen in its field of view. The stars are centered at different positions in different exposure frames. During four months of continuous observations during the polar night of 2008, about 0.3 million i-band images were obtained. In the latest version of the released photometric catalog, the effects of diurnal motion of the stars on the static CSTAR optical system can be obviously found. In this work, we update the CSTAR catalog by carefully analyzing and correcting the systematic errors caused by diurnal motion of stars on imperfectly flat-fielded frames.