SUPERHUMPS IN CATACLYSMIC BINARIES .8. V1159 ORIONIS

We report photometry of the cataclysmic variable V1159 Orionis for sim ilar to 400 hours over 168 nights during 1992-4. The long-term light c urves show that this is a dwarf nova of the SU UMa class, with normal outbursts recurring on a mean period of 4.0 days, and superoutbursts r ecurring on a period of 47.6 days. These periods wander slightly, as i s typical of the class. High-speed photometry at minimum light, far fr om superoutbursts, reveals a weak photometric signal at 89.83+/-0.10 m in, which is presumably the underlying orbital period of the binary. D uring superoutburst, large-amplitude superhumps are observed with P=92 .4 min. The superhumps appear very suddenly on the rising branch. In a few days they fade to a full amplitude of similar to 0.1 mag and beco me more complex in wave form. However, they can be traced throughout t he decline phase to quiescence, and even apparently succeed in endurin g to the next normal eruption. In fact, we note the occasional existen ce of superhumps at essentially all phases of the eruption cycle-not m erely in supermaxima, where they are very common and downright famous. The ''positive'' (P>P-orb) superhumps resemble in detail the common s uperhumps seen in the best-known SU UMa stars, and can be reasonably i nterpreted as arising from an eccentric accretion disk with an advanci ng Line of apsides. But additional subtle details are detected in V115 9 Ori. In one superoutburst the frequencies of the high harmonics are slightly higher than expected, and in another they are far lower than expected. And on two occasions there appeared ''negative'' superhumps (P<P-orb) with a period of 82.7+/-0.2 min. We discuss these features i n terms of the disk-precession model, but without any convincing resol ution. Two other periodic signals, of unknown origin, were detected: r apid oscillations (''DNOs'') with a period increasing from 29 to 34 s over 7 days in mid-decline from a superoutburst; and a probable signal near 8 c/day, appearing mainly in quiescence.