RZ Leo: unusual superhump Pdot Dear Colleagues, As reported by Ishioka-san, Subject: [vsnet-campaign-dn 379] RZ Leo observation at Kyoto > From the data set combined with all collaborators time series data, > the superhump period from Dec. 24 is 0.07854 d and almost constant. One of the most remarkable thing in the RZ Leo (true) superhumps is the almost constant superhump period. Most of (usual) SU UMa-type dwarf novae at this orbital periods show "textbook" period decrease at Pdot/P = -(a few)*10^(-5). Only few exceptions have been observed in, ultrashort-period, most infrequently outbursting objects. Some authors have attibuited to such negligibly small period decrease to the small tidal torque by the extremely light secondary (as in WZ Sge), but the RZ Leo is not clearly such a case! We have learned and will learn much from RZ Leo about the mystery of WZ Sge-type stars. Now, your contribution is most wanted at this and coming important stages of superoutburst! Regards, VSNET Collaboration team