ИСТИНА

High precision photometry of deeply eclipsed dwarf nova GY Cnc was provided in R band during the period 2013-2016 with two telescopes of Sternberg Astronomical Institute observational station in quiet and active states. A search of periodicities was carried out with the help of Lafler-Kinman method for the all data in quiescence. Obtained value Porb = 0d.1754420 placed GY Cnc above the 2-3 h period gap in the distribution of CVs periods. The shape of the mean phase light curves constructed with this period is variable for quiescence and outburst indicating that the physical properties of the accretion disk are quite different. During our monitoring two outbursts of this dwarf nova were detected: in April 2014 and October 2015. Our data evidence that duration of an outburst for GY Cnc is aproximately 10 days. During such outbursts the brightness increased on ~ 3.5 mag. The Rc light curve obtained in an active state shows a reflection effect and a possible shallow secondary eclipse around phase 0.5. In frames of combined model worked out for eclipsing CV-s by Khruzina (2011), the observational light curves were fitted with theoretical ones, parameters of the system components and their contribution to the total brightness of GY Cnc were estimated. The model gives a good quantitative match to the observations. From analysis of the brightness changes in quiescence we found that the range of the maximal brightness changes is delta R ~ 15m.7–16 m.4 and the depth of minimum (Rmean ~ 17 m.1),- in the range delta R ~ 16m.6–17 m.2.