Two-Color VR CCD Photometry of the Intermediate Polar 1RXS J062518.2+733433

Abstract

Results of 7 nights of CCD VR photometry of the intermediate polar 1RXS J062518.2 +733433 obtained at the Korean 1.8m telescope are reported. The corrected ephemeris for the orbital minimum is BJD (Orb.min) = 2453023.6159 (42)+0.1966431 (33) (E- 1735). The corrected ephemeris for the spin maximum is BJD (spin max) = 2452893 .78477 (10)+0.01374116815 (17) (E-15382) (cycle numbering corresponds to that of Staude et al.~2003). The variations of the shape of the individual spin variations are highly correlated in V and R. The phase of the spin maximum is found to be dependent on the orbital phase. The corresponding semi-amplitude of sinusoidal variations of phase is 0.11±0.03. This new phenomenon is explained by the changing viewing conditions of the accreting magnetic white dwarf, and should be checked in further observations this star and for other intermediate polars. To avoid influence of this effect on the analysis of the long-term spin period variations, the runs of at least one orbital period are recommended. Results of time series analysis are presented in tables.

Keywords

• cataclysmic variables
• intermediate polars
• RXS J062518.2+733433
• BG CMi
• FO Aqr