Superhumps in Cataclysmic Binaries. XIII. CP Puppis

We report new photometry of the old nova CP Puppis and study timing effects in the photometric waves seen during 1985-1998. A possibly stable signal is present at a period consistent with 0.06143(3) days, which is the orbital period deduced from spectroscopy. In addition, there is a transient signal at a slightly longer period. Measurement of the latter signal on individual nights, free from aliasing, yields P=0.0627(6) days, and measurement over longer baselines yields a mean value of P=0.0625(2) days. The properties of this signal (instability in period and amplitude, and period excess of 2% over P_orb) are the usual signatures of ``superhumps'' in cataclysmic variables.