ORBITAL PERIODS FOR THE CATACLYSMIC BINARIES VZ PYXIDIS, CC CANCRI, AND AH ERIDANI

This paper gives mean spectra and reports orbital periods based on rad ial velocities taken near minimum light for these dwarf novae, which a re all SU UMa stars or candidates. For VZ Pyx I find P-orb = 0.07332+/ -0.00003 d (= 105.58+/-0.04 min), for CC Cnc 0.07352+/-0.00005 d ( = 1 05.86 +/- 0.07 min), and for AH Eri, 0.2391+/-0.0005 d (= 5.738+/-0.01 2 hr). In AH Eri's case, orbital frequencies differing by +/- cycle d( -1) are marginally possible. The period for VZ Pyx is similarly ambigu ous, but Kato and Nogami's (PASJ, 49, 341, 1997a) superhump period and Remillard et al.'s (ApJ, 428, 785, 1994) short time base velocity stu dy constrain the alias choice to a single value. For CC Cnc, a prelimi nary measurement by Munari et al. (IAUC No. 5024, 1990) had indicated a P-orb in the 2-3 h period ''gap,'' but the P-orb found here is well short of the gap. AH Eri had been mentioned in the literature as a pos sible SU-UMa type dwarf nova; the long period found here makes this cl assification doubtful. The average spectrum of AH Eri shows molecular absorption bands consistent with an M-type secondary star. The long pe riod implies that AH Eri is similar to 5 times more distant than compu ted by Sproats et al. (MNRAS, 282, 211, 1997), which yields an absolut e magnitude in outburst in close agreement with that expected from P-o rb. With the orbital periods in hand, it would now be interesting to o btain new time series photometry aimed at confirming or refuting the c andidate similar to 40-min photometric modulations in AH Eri and VZ Py x which have been put forth in the literature.