Photometry of the SW Sextantis-type nova-like BH Lyncis in high state

¹ Department of Physics, Stockholm University, Albanova University Center, 106 91 Stockholm, Sweden
² Institute of Astronomy, Bulgarian Academy of Sciences, 72 Tsarighradsko Shousse Blvd., 1784 Sofia, Bulgaria e-mail: vall@physto.se,[vall;zk;vgenkov]@astro.bas.bg

Received: 16 November 2005
Accepted: 2 March 2006

Abstract

Aims.We present a photometric study of the deeply eclipsing SW Sex-type nova-like cataclysmic variable star BH Lyn.

Methods.Time-resolved V-band CCD photometry was obtained for seven nights between 1999 and 2004.

Results.We determined 11 new eclipse timings of BH Lyn and derived a refined orbital ephemeris with an orbital period of 0155875577(14). During the observations, BH Lyn was in high-state with mag. The star presents ~1.5 mag deep eclipses with mean full-width at half-flux of . The eclipse shape is highly variable, even changing form cycle to cycle. This is most likely due to accretion disc surface brightness distribution variations, most probably caused by strong flickering. Time-dependent accretion disc self-occultation or variations of the hot spot(s) intensity are also possible explanations. Negative superhumps with period of are detected in two long runs in 2000. A possible connection between SW Sex and negative superhump phenomena through the presence of tilted accretion disc is discussed, and a way to observationally test this is suggested.