BELGIAN ASTRONOMICAL SOCIETY V.V.S. - Working Group Variable Stars Cataclysmic Variables Circular No.47 1995, July 21 Ed.: T. Vanmunster, Walhostraat 1A, 3401 Landen, BELGIUM Internet: tvanmuns@innet.be TEL. 32-11-831504 P. Van Cauteren, de Borrekenslaan 54, 2630 Aartselaar, BELGIUM Internet: pvancaut@innet.be TEL. 32-3-8774098 =================================================================== GO Com [UGWZ:, 13.1p - 20p] =========================== Tonny Vanmunster, Landen, Belgium has detected a rare outburst of the dwarf nova GO Com. Robert Fidrich, Hungary has contacted us to report a possible confirmative observation by Robert Szabo, Hungary, using a 25-cm reflector. As there is still some uncertainty in the obser- vation of R. Szabo, additional confirmations are highly requested. 1995 Jul 16.951 UT, 13.3 (T. Vanmunster, 0.35-m refl., seq: GSC); Jul 18.509 UT, [13.6 (M. Moriyama, Japan, 0.33-m refl.) Jul 18.908 UT, [13.5 (P. Schmeer, 0.35-m refl.); Jul 19.86 UT, 13.2: (R. Szabo, Hungary, 0.25-m refl., seq: GSC); Jul 19.917 UT, [13.4 (P. Schmeer); Jul 19.928 UT, [13.5 (T. Vanmunster); Jul 20.921 UT, [13.5 (T. Vanmunster); In IBVS 3489, T. Kato and R. Hirata describe CCD photometry of GO Com, and report quasi-periodic modulation with an amplitude of 0.5 mag, and a "periodicity" of 33 min. The same paper mentions a major outburst of GO Com, observed on May 30, 1989 (mv 13.2) by Watanabe and Kato. As far as we can deduce from our "Outburst Activity Database on Selected Cataclysmic Variables", this constitutes the last reported positive observation of GO Com ! Another publication on GO Com (PASP, 102, 758-772, 1990), by S.Howell, P. Szkody a/o, mentions that GO Com has been seen in outburst at least three times. They further describe photometric observations showing approx. 0.5 mag flickering on top of a determined 95-min period (assumed to be the orbital period). The 95-min period, although seen with high confidence, may simply be flickering. In a recent message on VSNET, T. Kato communicates: "GO Com was disco- vered by Kowal as an eruptive object on a Palomar plate on 1977 July 1.213. The variable was confirmed to coincide with the suspected variable CSV 1959 = SVS 382. On the other hand, Usher independently discovered a very blue star of B=18.1 during the survey of the north galactic pole region. This star (US 31) was identical to GO Com. Vogt and Bateson classified this variable as a WZ Sge-type dwarf nova, because of its large outburst amplitude and low outburst frequency. During the 1989 outburst, the object attained a maximal magnitude of mv=13.2, which was followed by a rapid decline of about 1 mag in one day. This rapid decline suggests a normal outburst of an SU UMa star. Despite the seasonal gaps in monitoring this object, the extreme low outburst frequency of this dwarf nova now seems to be established. Apparent absence of long outbursts, infrequent short outbursts and possible excursion to a low state (mp ~ 20) may suggest a relationship to BZ UMa. Intensive observations during the present outburst, syste- matic searches for historical outbursts and determination of the physical parameters are recommended." It finally is interesting to note that GO Com is classified as a TOAD (Tremendous Outburst Amplitude Dwarf Nova) by S. Howell. CY UMa [UGSU, 11.9v - 17.0v] ============================ An outburst of this SU UMa-type dwarf nova has been reported by Tonny Vanmunster, Landen, Belgium. Subsequent confirmations have come from Patrick Schmeer, Bischmisheim, Germany and Eric Broens, Mol, Belgium. 1995 Jul 19.932 UT, [14.0 (T. Vanmunster, 0.35-m refl., seq: AAVSO); Jul 20.903 UT, [13.5 (P. Schmeer, 0.20-m SCT, seq: Fujino); Jul 20.913 UT, 13.9 (T. Vanmunster); Jul 20.922 UT, 13.5 (P. Schmeer); Jul 20.932 UT, 13.8 (E. Broens, 0.35-m refl., seq: AAVSO); Jul 20.994 UT, 13.3 (P. Schmeer); CY UMa was last seen in outburst on May 20, 1995 (P. Schmeer and T. Vanmunster) [CVC 37]. It was a normal (faint) outburst [CVC 40]. It's interesting to note that the present outburst and the two preceding ones all are separated by (almost) exactly 2 calendar months. FN And [UG, 13.5p - 17.5p] ========================== Tonny Vanmunster, Landen, Belgium reports another outburst detection. FN And, last seen in outburst on December 5th, 1994 (P. Schmeer) [CVC 22], is bright again. Eric Broens, Mol, Belgium has confirmed the event. Independent outburst detections have been reported by Patrick Schmeer, Bischmisheim, Germany and by Gary Poyner, Birmingham, UK. 1995 Jul 19.974 UT, [14.1 (T. Vanmunster, 0.35-m refl., seq: TA); Jul 20.951 UT, 13.3 (T. Vanmunster); Jul 20.963 UT, 13.4 (E. Broens, 0.35-m refl., seq: TA); Jul 21.000 UT, 13.2 (T. Vanmunster); Jul 21.041 UT, 13.3 (P. Schmeer, 0.20-m SCT, seq: TA); Jul 21.049 UT, 13.0 (G. Poyner, 0.40-m refl., seq: TA); During the December 1994 outburst, it reached a maximum brightness of mag. 13.2, and remained visible for 4 nights [CVC 23]. V542 Cyg [UGSS:, 13.0p - 18.3:p] ================================ Several observers have submitted their V542 Cyg observations, yielding a good coverage of the present outburst, which is summarized in the table below. ----------------------------------------------------------------------- DATE (UT) MAGN MS SEQ OBSERVER REMARKS SOURCE ------------------------------------------------------------------------ 1995 07 10.053 [13.9 mv AA Vanmunster, T. 35-cm refl. CVC 46 1995 07 13.906 [13.5 mv AA Vanmunster, T. 35-cm refl. CVC 46 1995 07 14.955 13.8 mv AA Vanmunster, T. 35-cm refl. CVC 46 1995 07 15.181 [13.5 mv AA Mc Kenna, J. 28-cm SCT VSNET 1995 07 15.997 13.9 mv AA Vanmunster, T. 35-cm refl. CVC 46 1995 07 16.11 13.8 mv AA Scovil, C. VSNET 1995 07 16.894 13.9 mv AA Vanmunster, T. 35-cm refl. CVC 46 1995 07 16.928 [13.5 mv AA Jensen, L. 33-cm refl. priv(JEN) 1995 07 16.945 13.7 mv AA Broens, E. 35-cm refl. CVC 46 1995 07 19.88 14.1 mv AA Szabo, R. 25-cm refl. priv(FID) 1995 07 19.900 [13.9 mv AA Vanmunster, T. 35-cm refl. VVS 1995 07 20.903 [13.9 mv AA Vanmunster, T. 35-cm refl. VVS CVAP UPDATE =========== Two extremely interesting cataclysmic variables have been added to the CVAP (Cataclysmic Variables Alert Programme). It concerns : NSV05543 position (1950.0) : R.A. = 12h16m09s Decl = +40d18.3' type : UG? mag. range : 12.0 - [14p No additional information available on this object S10932 position (J2000.0): R.A. = 12h39m32.1s Decl = +21d08'06" type : UG:+E mag. range : 13.4 - 18.5p This a suspected eclipsing CV, and only the third member of eclipsing SU UMa-type dwarf novae in the northern hemi- sphere. More information on S10932 is given in IBVS 4182. Paul Van Cauteren, Aartselaar, Belgium has prepared GSC-based charts for the two new CVAP objects. They are available from the editors upon simple request. Tonny Vanmunster