BELGIAN ASTRONOMICAL SOCIETY V.V.S. - Working Group Variable Stars Cataclysmic Variables Circular No.101 1996, July 18 Ed.: T. Vanmunster, Walhostraat 1A, 3401 Landen, BELGIUM Internet: tvanmuns@innet.be TEL. 32-11-831504 -------------------------------------------------------------- The CATACLYSMIC VARIABLES Home Page: http://www.cv.psi.edu =================================================================== WX Cet [UGWZ, 9.5v - 17.5v] =========================== Berto Monard, Pretoria, South Africa and Albert Jones, New Zealand report their (independent) discovery of a superoutburst of this most interesting UGWZ-type dwarf nova. WX Cet is part of the TA/BAAVSS Recurrent Objects Programme and included in Steve Howell's list of TOADs. Available observations : 1996 Jul 17.080 UT, [11.9 (P. Schmeer, 0.20-m SCT, Germany); Jul 17.646 UT, 12.0 (A. Jones, New Zealand); Jul 17.656 UT, 11.8 (A. Jones); Jul 17.684 UT, 11.8 (A. Jones); Jul 17.731 UT, 11.6 (A. Jones); Jul 18.078 UT, 11.6 (P. Schmeer); Jul 18.087 UT, 12.0 (B. Monard, South Africa); Jul 18.129 UT, 12.0 (B. Monard); Taichi Kato, Kyoto University, Japan remarks in a VSNET message : "Maximal magnitudes of superoutbursts of WX Cet tend to have a large scatter (~3 mag) as compared to other 'usual' SU UMa-type dwarf novae (e.g. T. Kato, IBVS No. 4256). From this point, the present magnitude already suggests a superoutburst. Since strong aliasing of previous superhump observations has not yet completely solved the superhump nature, there remains much to be done regarding superhump photometry. WX Cet showed another rather peculiar feature during the final fading stage of a superoutburst. In contrast to most SU UMa-type dwarf novae (including an extreme case of AL Com), the termination of the 1991 superoutburst was not accompanied by a rapid decline." Joe Patterson, Dept. of Astronomy, Columbia University, USA reports : "Photoelectric photometry on the CTIO 1-m by Jonathan Kemp and Susan Kassin showed 0.25 mag superhumps in WX Ceti on the night of July 17/18. Thus the present outburst is very likely to be a supermaximum. A July supermax isn't perfect, but it's still the best seasonal timing WX Cet has ever delivered. O'Donoghue et al. (1991; MNRAS 250, 363) struggled valiantly to find the superhump period from single-site observations in early June 1989. Their best-fit periods were in the range 70-80 min, an awfully interesting range! But these were based on observations of only ~2 hr/night (because of the unfavorable location of Cetus in June), far too brief to identify the period securely. Thus the superhump period remains unknown. Now we can fix that. But it probably requires a multi-longitude collaboration - because even now we can only get 4-hour runs on the star, still uncomfortably short. We would love to hear from other observers who are able to get superhump timings. At magnitude 11.7 and with a full amplitude of 0.25 mag, the project may even be feasible for very experienced visual observers." The previous outburst of WX Cet was observed on January 21, 1994 by Thouet, York, Overbeek a/o (max. mag. 11.7), according to the Outburst Activity Database on Selected Cataclysmic Variables. DM Lyr [UGSU, 13.6p - 18p] ========================== What many observers had suggested, finally has been proven : DM Lyr is a SU UMa type dwarf nova. Evidence by CCD observations has been obtained independently by the Ouda Team, Kyoto University, Japan and by Tonny Vanmunster, CBA Belgium. Included are the corresponding messages on VSNET : "We, Ouda Team, observed DM Lyr last night (7/16) and detected superhumps with an amplitude of about 0.1 mag. DM Lyr has, thus, proven to be a new member of SU UMa stars! Our preliminary period analysis gives 0.066 (+-0.002) day as the best estimated superhump period." "The DM Lyr CCD photometry, obtained last night (July 16/17) at the CBA Belgium (unfiltered 90s exposures using a 25-cm SCT with ST-7 CCD) clearly shows the existence of superhumps in this system (hence proving the SU UMa nature). A very preliminary analysis of the superhump period yields a best value of 0.067d +/- 0.001d (PDM method) and a mean ampli- tude of 0.08 mag." Photometric summary (continuation of the table in CVC 99) : ----------------------------------------------------------------------- DATE (UT) MAGN MS SEQ OBSERVER REMARKS SOURCE ----------------------------------------------------------------------- 1996 07 12.506 14.13 CU Kato, Nogami VSNET 1996 07 12.617 14.6 mv Takahashi VSNET 1996 07 12.968 14.8 CU Jensen, L. VSNET 1996 07 13.026 14.4 mv TA Poyner, G. VSNET 1996 07 13.946 14.2 mv AA Vanmunster, T. VVS 1996 07 14.956 14.5 mv TA Poyner, G. VSNET 1996 07 14.971 14.4 mv Day, J. VSNET 1996 07 15.132 14.4 CU Ouimet, P. PRIV 1996 07 15.960 14.7 mv TA Poyner, G. VSNET 1996 07 15.993 14.6 mv Day, J. VSNET 1996 07 16.443 14.6 CU Kato, Baba VSNET 1996 07 16.535 [14.9 mv Takahashi VSNET 1996 07 16.87 14.4 mv Szentasko, L. VSNET 1996 07 16.967 14.6 mv TA Poyner, G. VSNET 1996 07 16.984 15.0 mv TA Worraker, B. PRIV 1996 07 17.008 15.5 CU Jensen, L. VSNET 1996 07 17.041 15.2 mv TA Worraker, B. PRIV 1996 07 17.444 14.60 CU Kato, Baba VSNET 1996 07 17.447 14.63 CU Kato, Baba VSNET Var25 Oph [UG, 15.0 - <21.0p] ============================= Follow-up observations of the outburst reported in CVC 100 are listed below. Please note that Gary Poyner, UK very likely made the first ever visual observation of this object. ----------------------------------------------------------------------- DATE (UT) MAGN MS SEQ OBSERVER REMARKS SOURCE ----------------------------------------------------------------------- 1996 07 12.515 16.0 CU Iida, M. CVC 100 1996 07 13.014 [14.7 mv Poyner, G. VSNET 1996 07 13.904 16.4 CU Vanmunster, T. CVC 100 1996 07 14.946 [15.0 mv Poyner, G. VSNET 1996 07 15.914 [16.5 CU Vanmunster, T. VVS 1996 07 15.934 16.2 CU Jensen, L. VSNET 1996 07 15.949 15.7 mv Poyner, G. VSNET 1996 07 16.944 [17.8 CU Vanmunster, T. VVS 1996 07 16.959 [15.5 mv Poyner, G. VSNET V630 Cyg [UGSU:, 13.4p - 17.2p] =============================== The V630 Cyg outburst has remained a rather faint outburst, as indicated by the photometric summary below. Remark that the table contains some conflicting observations, and a brief rebrightening (unconfirmed). ----------------------------------------------------------------------- DATE (UT) MAGN MS SEQ OBSERVER REMARKS SOURCE ----------------------------------------------------------------------- 1996 07 10.085 14.2 mv AA Broens, E. CVC 99 1996 07 10.948 [14.9 mv AA Skalak, P. PRIV 1996 07 11.039 14.4 mv Poyner, G. CVC 99 1996 07 12.534 15.6 CU Kato, Nogami VSNET 1996 07 12.581 15.3 CU Iida, M. VSNET 1996 07 12.982 15.5 CU Jensen, L. VSNET 1996 07 13.049 [14.1 mv Poyner, G. VSNET 1996 07 14.990 [15.2 mv Poyner, G. VSNET 1996 07 15.902 [16.4 CU Vanmunster, T. VVS 1996 07 15.992 14.5 mv Poyner, G. VSNET 1996 07 15.993 [14.9 mv AA Skalak, P. PRIV 1996 07 16.491 17.9 CU Kato, Baba VSNET 1996 07 16.979 [17.1 CU Jensen, L. VSNET 1996 07 17.516 18.8: CU Kato, Baba VSNET Tonny Vanmunster