TIME-RESOLVED CCD PHOTOMETRY OF A SAMPLE OF PALOMAR-GREEN CATACLYSMIC VARIABLE CANDIDATES

We present the results of a photometric study of 12 cataclysmic variables from the Palomar-Green survey of high-galactic-latitude ultraviolet excess objects. Nine of the twelve (PG 0917+342, PG 0943+521, PG 1114+187, PG 1119+147, PG 1316+678, PG 1510+234, PG 1524+622, PG 1633+115, and PG 2133+115) are part of Ringwald's magnitude-limited sample of cataclysmic variables. Among these nine, we identify an unusual new SU UMa dwarf nova PG 0943+521, and find a superhump period Psh=0.0656±0.0001d. We confirm the presence of "permanent superhumps" in the nova-like variable PG 0917+342. We find photometric periodicities in PG 1633+115, but an aliasing problem prohibits us from distinguishing between periods of 3.94h, 3.43h, and 3.38h. PG 1510+234 exhibits large scale brightness variations, but shows no evidence of any photometric periodicity. Three objects, PG 1114+187, PG 1119+147, and PG 1316+678, exhibit no obvious variability and are unlikely to be cataclysmic variables. Of the remaining three objects not in the complete sample, PG 0240+066, PG 1116+349, and PG 0911-066, we identify the latter as a likely dwarf nova, possibly of the WZ Sge subtype, and we find a photometric period, possibly orbital in nature, of P=82.931±0.001 min. PG 0240+066 and PG 1116+349 exhibited no variability during our observations and are unlikely to be cataclysmic variables. Finally, we briefly examine the fraction of eclipsing cataclysmic variables in the sample as it relates to the importance of selection effects.