The 2006/2007 photometric activity of three chromospherically active stars: V2075 Cyg, FG UMa and BM CVn

We present new multiband CCD photometric observations of three chromospherically active stars with long periods (V2075 Cyg, FG UMa and BM CVn). The observations were made at the Çanakkale Onsekiz Mart University Observatory in 2006 and 2007. We analyzed BVRI (Bessell) CCD observations of these three RS CVn-type SB1 binaries with the following three steps: (i) Photometric rotation periods were obtained by analyzing their light variations with a differential corrections method and a Fourier transform technique. (ii) Light variations, observed over three or more consecutive orbital cycles, were investigated by using dark (cool) spot models with the program SPOT. (iii) Surface differential rotation coefficients for the primary components of these binaries were derived using our own photometric periods together with orbital periods taken from the literature.