Multi-epoch time-resolved photometry of the eclipsing polar CSS081231:J071126+440405

The eclipsing polar CSS081231:071126+440405 turned bright (V-max approximate to 14.5) in late 2008 and was subsequently observed intensively with small and medium-sized telescopes. A homogeneous analysis of this comprehensive dataset comprising 109 eclipse epochs is presented and a linear ephemeris covering the five years of observations, about 24000 orbital cycles, is derived. Formally this sets rather tight constraints on the mass of a hypothetical circumbinary planet, M-pl 2 M-Jup. This preliminary result needs consolidation by long-term monitoring of the source. The eclipse lasts 433.08 +/- 0.65 s, and the orbital inclination is found to be i = 79.3 degrees-83.7 degrees. The centre of the bright phase displays accretion-rate dependent azimuthal shifts. No accretion geometry is found that explains all observational constraints, suggesting a complex accretion geometry with possible pole switches and a likely non-dipolar field geometry. ((c) 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)