Doppler tomography and photometry of the cataclysmic variable 1RXS J064434.5+334451

We have obtained simultaneous photometric and spectroscopic observations of the cataclysmic variable 1RXS J064434.5+334451. We have calibrated the spectra for slit losses using simultaneous photometry, allowing us to construct reliable Doppler images from H... and He ii 4686-A emission lines. We have improved the ephemeris of the object based on new photometric eclipse timings, obtaining HJD = 245 3403.759 533 + 0.269 374 46E. Some eclipses present a clear internal structure, which we attribute to a central He ii emission region surrounding the white dwarf, a finding supported by Doppler tomography. This indicates that the system has a large inclination angle i = 78 plus or minus 2... We have also analysed the radial velocity curve from the emission lines to measure its semi-amplitude, K sub( 1), from H... and He ii 4686 and derive the masses of the components M sub( 1) = 0.82 plus or minus 0.06 M..., M sub( 2) = 0.78 plus or minus 0.04 M... and their separation a = 2.01 plus or minus 0.06 R... The Doppler tomography and other observed features in this nova-like system strongly suggest that this is a SW Sex type system. (ProQuest: ... denotes formulae/symbols omitted.)