OPTICAL POLARIZATION AND X-RAY DATA ON THE AM HER STAR RE J1844-74

We report optical and X-ray observations of the AM Her system RE J1844 - 74 using the Anglo-Australian Telescope (AAT) and ROSAT. From previ ously published data and these new data we derive a new accurate ephem eris for the spin period of the white dwarf. We find we cannot simulta neously fit the green and red polarization data. However, we can fit t hem separately using different values of the plasma parameter, Lambda. We investigate the possible reasons for this result. Furthermore, we find that the polarization data require long narrow accretion arcs. Th is is in contrast to results on eclipsing AM Her systems which tend to favour accretion regions that are relatively small, We briefly explor e the possible effects that may influence the determination of the siz e of the accretion region from these different methods. We find eviden ce that the main accretion region of RE J1844 - 74 has a magnetic fiel d strength similar to 10 MG less than its secondary pole, and that the system inclination is moderately high, Our X-ray data are out of phas e with the optical data, consistent with our current view of the accre tion flow in AM Her systems.