EUVE Observations of Cataclysmic Variables

We present preliminary results of extreme ultraviolet (EUV; 50--750 Angstroms) observations of the presently known cataclysmic variables selected from Ritter's (1994) forthcoming catalog of cataclysmic binaries. The Extreme Ultraviolet Explorer (EUVE) detected 18 CVs during its all-sky survey, most of them only in the Lexan/boron bandpass (50--180 Angstroms). Most of the detected systems are magnetic, AM Her-type stars, similar to those found by the ROSAT WFC sky survey. EUVE detected two weakly magnetic systems, or DQ Her-type CVs. Most nonmagnetic CVs, even dwarf novae in outburst, are intrinsically weak EUV sources. This is made evident by the low EUVE count rates of the two nonmagnetic systems detected---the dwarf nova VW Hyi in outburst and the novalike variable IX Vel. Count rates and upper limits are given for 231 cataclysmic variables in the four EUVE wavebands, centered roughly at 83, 171, 405, and 555 Angstroms. We estimate temperatures and interstellar columns for these systems. We address the short term variability in some of the stronger systems and also the long-term variability of those systems, including AM Her, that were observed twice with a six month separation. This work has been supported by NASA contract NAS5-30180 and grant NAGW-2029.