RJ-051542- A NEW MAGNETIC, ECLIPSING, CATACLYSMIC VARIABLE(0104.7 )

We present photometric and spectroscopic observations of a recently id entified X-ray bright, magnetic cataclysmic variable, RJ 051542+0104.7 . The X-ray source was discovered serendipitously by Waiter et al. (19 94; Walter and Zoonematkermani 1994), and their data imply the presenc e of a heated white dwarf compatible with a magnetic accretion column. Buckley (1994) has reported the presence of circular polarization. Ou r optical photometry shows that the system undergoes eclipses with a p eriod of 7.9835 +/- 0.0002 hours. The eclipse is 1 magnitude deep and appears to be total. Our spectra were all obtained near eclipse and sh ow a strong blue continuum with broad Balmer emission as well as He II (4686 and 5411 Angstrom), C III/N III (4650 Angstrom) and He I lines. The blue continuum and emission lines disappear during eclipse, leavi ng only the spectrum of a M0 star. Using the observed magnitude during eclipse and ignoring interstellar extinction, the distance is similar to 500 pc. For the secondary to fill its Roche lobe, it must be at le ast 20% larger than that of a normal dM0 star. This may indicate the r ed dwarf is far from LTE due to strong magnetic braking. We find evide nce for cyclotron humps in the continuum spectrum which imply a magnet ic field strength in the cyclotron emitting region of up to 55 MG. The unexpected existence of a long period AM Her system should provide co nstraints on models of polar evolution.