Superhumps in Cataclysmic Binaries. X. V1974 Cygni (Nova Cygni 1992)

We report photometry of V1974 Cygni, the remnant of Nova Cygni 1992. A very nearly stable photometric signal with a period of 117.012 (\pm.002) min was present throughout 1993-6, with declining amplitude. This appears to be the underlying orbital period of the binary; at least during 1993, it probably manifested itself through the external heating of the secondary star's atmosphere. We interpret the declining signal amplitude as the result of white dwarf cooling after the nova ouburst. This suggests an e-folding timescale of \sim 80 d for luminosity decline, consistent with the UV flux which probably arises from the heated accretion disk. During 1994-1996 there appeared another photometric signal, far less stable. The period varied in the range 122.4-122.7 min, with an average \mid $dot P$ \mid of about 10$^6$. We interpret this as a "superhump," a common phenomenon in cataclysmic binaries of short $P_orb$ and high accretion rate. (SECTION: Stars)