We present a period analysis of the well known β Lyrae type eclipsing binary GO Cyg (P= 0d .7177). Several new times of minimum light, recorded photoelectrically, have been gathered. Analysis of all available eclipse timings of GO Cyg has confirmed a significant period increase with rate of 2.52 X 10-10day / cycle, also new period has been estimated. New linear and quadratic ephemerides have been calculated for the system.

• M. M. ELKHATEEB(Department of Astronomy, National Research Institute of Astronomy and Geophysics (NRIAG))