System parameters of the long-period polar V1309 Ori

Based on high-resolution optical spectroscopy in the blue and the near infr a-red spectral range, we derived velocity images (Doppler tomograms) of the mass-donating secondary star and the accretion stream of the long-period e clipsing polar V1309 Ori (RX J0515.41+0104.6). Combined with HST-spectrosco py of high time resolution and optical photometry we were able to derive th e main system parameters and to determine the accretion geometry of the bin ary. The length of the eclipse of the white dwarf is Deltat(ecl) = 2418 +/- 60 s, the mass ratio Q = 1.37-1.63, and the orbital inclination i = 76.6 d egrees -78.9 degrees. The surface of the secondary star could be resolved i n the Doppler image of NaI absorption lines, where it shows a marked deplet ion on the X-ray irradiated side. The accretion geometry proposed by us wit h a nearly aligned rotator, co-latitude delta similar or equal to 10 degree s, tilted away from the ballistic stream, azimuth chi similar or equal to - 35 degrees, explains the shape of the emission-line Doppler tomograms and t he shape of optical/UV eclipse light curves.