BELGIAN ASTRONOMICAL SOCIETY V.V.S. - Working Group Variable Stars Cataclysmic Variables Circular No.116 1996, December 10 Ed.: T. Vanmunster, Walhostraat 1A, 3401 Landen, BELGIUM Internet: tvanmuns@innet.be TEL. 32-11-831504 =================================================================== DX And [UG, 10.9p - 16.4p] ========================== We have been informed by the AAVSO (through AAVSO News Flash 83) about a possible outburst of this long-period dwarf nova, which is on the TA/BAAVSS Recurrent Objects Programme. A confirmative obser- vation has been reported by R. Modic on VSNET : 1996 Dec 08.223 UT, 14.9 (R. Modic, 0.50-m refl., seq: VSNET); Dec 09.042 UT, 13.8 (J. Griese); Dec 09.157 UT, 13.8 (J. Griese); Dec 10.101 UT, 13.9 (R. Modic); The previous outburst of DX And was reported on February 29, 1996 by L. Jensen, Denmark [CVC 84]. In an interesting note on VSNET, Taichi Kato, Kyoto University, Japan remarks : "The present early detection, if confirmed, of an outburst of DX And might provide another ... excellent opportunity in probing the accretion disks in dwarf novae having long orbital periods, whose outbursts seem to start from the inner part of accretion disks. GK Per and CH UMa all showed a "plateau" before reaching maximum light, during which the heating wave seems to propagate through the accretion disk inside-out. Follow-up (multicolor and time-resolved) observations are recommended at this moment of the event." Spectroscopic and photometric observations of DX And, as well as its physical parameters, are discussed in length in (Drew, J.E. et al., 1993, MNRAS, 260, 803-818). EG Cnc [NL/UG:, 11.9v - 17:v] ============================= The EG Cnc outburst, announced in our previous CVC issue, has received wide coverage, both from amateur and professional astro- nomers, and so far has already resulted in extremely interesting photometric results. The light curve below is a compilation of observations received from observers world-wide. ------------------------------------------- DATE (UT) MAGN MS OBSERVER ------------------------------------------- 1996 11 21.082 [15.2 mv Poyner 1996 11 21.23 [13.7 mv Schmeer 1996 11 30.917 12.5 mv Schmeer 1996 11 30.951 12.0 mv Schmeer 1996 11 30.989 11.8 mv Schmeer 1996 12 01.021 12.1 mv Vanmunster 1996 12 01.130 11.7 mv Schmeer 1996 12 01.248 11.7 mv Schmeer 1996 12 01.804 11.6 mv Watanabe 1996 12 02.038 12.5 mv Poyner 1996 12 02.298 12.0 mv Hanson 1996 12 02.333 11.4: mv Burrows 1996 12 02.710 12.44 CV Kiyota 1996 12 02.819 11.8 mv Watanabe 1996 12 02.992 11.8 mv Schmeer 1996 12 03.282 11.8 mv Dillon 1996 12 03.737 12.1 mv Watanabe 1996 12 03.837 11.8 mv Makiguchi 1996 12 04.008 11.9 mv Worraker 1996 12 04.060 11.9 mv Worraker 1996 12 04.949 12.0 mv Worraker 1996 12 04.979 12.7 mv Poyner 1996 12 05.023 12.0 mv Brincat 1996 12 05.972 12.8 mv Schmeer 1996 12 06.072 12.8 mv Schmeer 1996 12 06.154 12.8 mv Schmeer 1996 12 06.760 12.5 mv Watanabe 1996 12 07.00 12.5 mv Pietz 1996 12 07.630 12.4 mv Watanabe 1996 12 07.738 12.47 CV Ouda 1996 12 07.831 12.3 mv Watanabe 1996 12 07.839 12.5 mv Itoh 1996 12 07.93 12.4 mv Pietz 1996 12 08.795 12.53 CV Ouda Various groups and observatories attempted V-band and unfiltered CCD photometry during almost every phase of the EG Cnc outburst. Although the eruption is still ungoing, we'd like to present a first summary of some of the most exciting results received so far. The first time-series photometry data were reported by Katsura Matsu- moto of Osaka Kyoiku University, Japan, on December 4th, 1996 through VSNET : "We obtained a continuous (four hours) CCD V-band light curve of EG Cnc last night. The observed light curve shows superhumps with a low amplitude, approximately between 0.03 and 0.04 magnitude. A preli- minary analysis yielded a period of 0.058 day, which is one of the shortest known among dwarf novae." A very comprehensive set of multi-longitude photometry data were col- lected by the CBA network (Joe Patterson, Jonathan Kemp, Dave Harvey, Tonny Vanmunster, Dave Skillman and S. Kiyota) : "We have obtained time-series photometry of EG Cnc on each night (December 1-5) since Schmeer's exciting recovery of the star after its 19-year slumber. We used data from four stations of the Center for Backyard Astrophysics (CBA), and added brief coverage from the Cerro Tololo 1-m telescope. The star continues a linear decline at 0.12 mag/night, and was at V=12.83 on December 5.3 UT. During December 1-3, the star showed a periodic modulation at 0.0572+-0.0002 d, with ever-decreasing amplitude (averaging 0.03 mag peak-to-trough). On December 4-5, the signal weakened further and disappeared into the noise." After this weakening of the superhumps, a gradual recovery was obser- ved starting from December 5/6, 1996. In a communication by Joe Patterson, CBA New York, we read : "During a CBA-Maryland run of six hours centered on December 5.35 UT, the waves were at 0.027 mag and slightly growing. A Cerro Tololo observation on December 6.3 showed that the amplitude had grown to 0.13 mag (at V=13.0), and on December 7.3 it had grown further to 0.18 mag while the star had brightened to V=12.5. The period was probably 0.0606+-0.0002 d, with a chance of really being 0.0645 d, the one-day alias." This amplitude growing and period analysis was shortly afterwards confirmed by the Ouda team of Kyoto University, Japan : "We have carried out time-resolved photometry of EG Cnc from Dec. 7.68 to 7.81 at Ouda Station using a 60-cm reflector + CCD + Johnson V filter. A preliminary analysis using PDM method gives 0.061 (+- 0.001) d as the best estimated period ... Superhumps have grown to 0.20 mag." Further superhump period determinations were reported by Allen Shafter, Scott Dahm and Hye-kyung Lee (CBA communication), and based on observations obtained on Dec 7 and Dec 8, 1996. They derived a superhump period of 0.0604 (+- 0.0001) days and a full amplitude of approx. 0.13 mag. FX Cep [UGSS?, 15.0p - 17.5p] ============================= The FX Cep outburst, reported in CVC 114, has received little attention, mainly due to bad weather circumstances throughout most of Europe and all the excitement around EG Cnc. Observations received until now : 1996 Nov. 29.993 UT, [14.2 (G. Poyner, 0.40-m refl., seq: GSC); Nov. 30.814 UT, 14.5 (E. Broens, 0.35-m refl., seq: GSC); Nov. 30.930 UT, 14.9 (T. Vanmunster, 0.25-m SCT + ST-7 unfilt.); Dec. 01.781 UT, 14.6 (G. Poyner); Dec. 02.810 UT, 14.6 (G. Poyner); Dec. 04.839 UT, [14.5 (G. Poyner); Given the very few observations, the uncertainty about the dwarf nova subtype remains. QY Per [UG, 14.2p - <20p] ========================= Jochen Pietz, Germany reports an outburst of this poorly studied cataclysmic variable, which is included in the Belgian CVAP (Cata- clysmic Variables Alert Programme). Although confirmative observations are still lacking at present, we include the reported outburst in this CVC in order to raise interest in this dwarf nova. We strongly recommend follow-up observations, since virtually nothing is known about QY Per. We have requested time-series photometry data from some astronomers already, but would like to involve more observatories in our present quest for data. The observation by J. Pietz : 1996 Dec 07.88 UT, 14.3 (J. Pietz); The previous outburst of QY Per (the second one ever observed visually) was reported on August 21, 1995 by T. Vanmunster, Belgium [CVC 54] and further discussed in CVC 55. It turned out to be a short outburst. Tonny Vanmunster