BELGIAN ASTRONOMICAL SOCIETY V.V.S. - Working Group Variable Stars Cataclysmic Variables Circular No.51 1995, August 03 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] =========================== The fact that dwarf novae can be highly unpredictable has been proven several times in the past. An outstanding example is currently showing up with a post-maximum brightening of GO Com (see outburst announcement in CVC 47). Gary Poyner, Birmingham, UK has forwarded us a message from Robert Fidrich, Hungarian Astronomical Association HAA, in which he announces a positive observation by Laszlo Szentasko, Hungary, as follows : 1995 Jul 30.845 UT, 13.3 (L. Szentasko, 0.33-m refl., seq: GSC); The observation has been confirmed by Taichi Kato, Kyoto University, Japan on VSNET : "We have just confirmed this phenomenon of GO Com. Several CCD images taken around July 31 10h 44m UT (evening twilight) clearly show this object again in outburst. A rough magnitude estimate gives V~13.5. I wonder what's happening in this CV ! Follow-up observa- ions are highly encouraged." ----------------------------------------------------------------------- DATE (UT) MAGN MS SEQ OBSERVER REMARKS SOURCE ----------------------------------------------------------------------- 1995 07 16.951 13.3 mv GSC Vanmunster, T. 35-cm refl. CVC 47 1995 07 18.509 [13.6 mv Moriyama, M. 33-cm refl. VSNET 1995 07 18.908 [13.5 mv Schmeer, P. 20-cm SCT priv(SCH) 1995 07 19.917 [13.4 mv Schmeer, P. 20-cm SCT priv(SCH) 1995 07 19.928 [13.5 mv GSC Vanmunster, T. 35-cm refl. CVC 47 1995 07 20.921 [13.5 mv GSC Vanmunster, T. 35-cm refl. CVC 47 1995 07 21.87 [15.2 mv GSC Fidrich, R. 45-cm refl. priv(FID) 1995 07 21.87 [15.2 mv GSC Bakos, G. 45-cm refl. priv(FID) 1995 07 22.88 [15.2 mv GSC Fidrich, R. 45-cm refl. priv(FID) 1995 07 22.88 [15.2 mv GSC Bakos, G. 45-cm refl. priv(FID) 1995 07 22.923 [14.4 mv GSC Vanmunster, T. 35-cm refl. VVS 1995 07 25.481 [15.0 CU Iida, M. 16-cm+ST-6 VSNET 1995 07 25.483 16.6 CV *Kato, T. 60-cm+ST-6 VSNET 1995 07 27.840 [14.4 mv GSC *Fidrich, R. 45-cm refl. VSNET 1995 07 27.910 [14.4 mv GSC *Szabo, R. 45-cm refl. VSNET 1995 07 30.845 13.3 mv GSC *Szentasko, L. 33-cm refl. VSNET 1995 07 31.445 13.6 CV GSC *Kato, T. 60-cm refl. VSNET 1995 08 01.447 13.5 CV GSC *Kato, T. 60-cm refl. VSNET 1995 08 01.895 13.4 mv GSC *Vanmunster, T. 35-cm refl. VVS V1028 Cyg [UGSS, 13.0p - 18p] ============================= We have received independent outburst observations of V1028 Cygni (CVC 48) from Janet Mattei, AAVSO. They are included in the photometric table below. In response to CVC 48, Janet Mattei, AAVSO, communicates : "I am delighted to see your e-mail (CVC 48) with further observations of the outburst of V1028 Cyg. AAVSO observers D. York and T. Burrows reported the outburst on Friday (1995, July 28). Due to the fact this star has had a number of short outbursts, we wanted to wait one more day, before putting the announcement. Further bright magnitudes and the observations from T. Kato confirm our belief that this star is an SU UMa type (possibly TOAD) dwarf nova. Again, congratulations to all the observers who "caught" the outburst, all independently. It is great to see how close these stars are being monitored by variable star observers around the world." J. Mattei further adds : "V1028 Cyg has been closely monitored by AAVSO since 1981. Although it is classified as an SS Cyg type dwarf nova in the Fourth edition of the General Catalog of Variable Stars and also in the Catalog and Atlas of Cataclysmic Variables by Downes and Shara (PASP, 105, 127; 1993), the observations in the AAVSO International Database suggest that it may be an SU UMa type - TOAD - dwarf nova. It has had several short and faint outbursts that lasted between 1 to 4 days and reached maximum magnitude between 13.5 and 14.4. The AAVSO records indicate that the September 1992 outburst was a long one, which started on the 5th (as reported, again, by D. York), reached maximum magnitude of 12.8 on the 6th and was brighter than magnitude 14.2 until the 16th of September, 1992. This may have been a superoutburst. The fact that the current outburst is bright suggests that it may also be a superoutburst." Soon afterwards, T. Kato (Ouda Team), Kyoto University, Japan reported detection of superhumps: "We obtained four hours' CCD photometry between July 30.63 and 30.81. The light curve clearly indicates that "true" super- humps have grown. The amplitude of superhumps has grown to 0.07 mag, with a familiar single-peaked hump structure. A preliminary period analysis yields the best estimate of the superhump period as 0.065 +/- 0.001 day (slightly affected by short duration of the run). It is curious that the period reported for July 29 observations was significantly longer. We have re- analyzed the last night data, by selecting high S/N data, and obtained a period of 0.070 +/- 0.001 day, which is still longer than the current value. We can not say at this time the cause of this discrepancy in periods." Additional CCD photometry observations communicated by T. Kato : "CCD photometry at Ouda Station (Kyoto University) shows that the super- humps of V1028 Cyg now seem to have fully grown. The light curve shows characteristic triangular superhumps with an amplitude of 0.29 mag in V. A period analysis on July 31 data shows a strong signal at 0.063 day. An analysis of the merged data of July 30 and 31 also shows a strong peridicity at 0.0626 day (and much less likely one-day alias 0.0670 day). From the current observations, we may now adopt 0.0626 day as a superhump period of V1028 Cyg. This short superhump period can be comparable to those of T Leo, VY Aqr and AQ Eri, all of which show relatively infrequent (super)outburst activity. The low outburst frequency of V1028 Cyg seems to be consistent with what is expected from the observed superhump period. Both T Leo and VY Aqr are known to show "double maxima", so close monitoring of V1028 Cyg even after the end of the present superoutburst is recommended. The origin of discordant period observed at the earliest stage of outburst is still not understood." The most recent CCD photometry observations reported by T. Kato, suggest a shortening of the superhump period : "A period analysis of combined data between July 30 and Aug. 1 gives an updated estimate of superhump period in V1028 Cyg: Psh = 0.0620 day. This value is somewhat shorter than reported earlier, suggesting a shortening of the period. Superhump maximum occurred on Aug. 1.695 UT." ----------------------------------------------------------------------- DATE (UT) MAGN MS SEQ OBSERVER REMARKS SOURCE ----------------------------------------------------------------------- 1995 07 27.156 [16.0 mv AA York, D. 45-cm refl. priv(MAT) 1995 07 28.187 13.5 mv AA York, D. 45-cm refl. priv(MAT) 1995 07 28.235 13.5 mv AA York, D. 45-cm refl. priv(MAT) 1995 07 28.263 13.5 mv AA Burrows, T. priv(MAT) 1995 07 28.916 12.8 mv AA Pietz, J. 40-cm refl. VSNET 1995 07 28.920 12.7 mv AA Pietz, J. 40-cm refl. VSNET 1995 07 28.967 12.7 mv AA Pietz, J. 40-cm refl. CVC 48 1995 07 29.149 12.7 mv AA York, D. 45-cm refl. priv(MAT) 1995 07 29.167 12.7 mv AA York, D. 45-cm refl. priv(MAT) 1995 07 29.217 12.7 mv AA York, D. 45-cm refl. priv(MAT) 1995 07 29.598 13.0V CV GSC Kato. T. 60-cm refl. priv(KAT) 1995 07 29.911 12.9 mv AA Szentasko, L. 33-cm refl. priv(SZE) 1995 07 29.913 13.0 mv AA Vanmunster, T. 35-cm refl. CVC 48 1995 07 29.930 12.8 mv GSC Schmeer, P. 20-cm SCT CVC 48 1995 07 30.216 13.1 mv AA Mc Kenna, J. 28-cm SCT VSNET 1995 07 30.87 12.9 mv AA Szentasko, L. 33-cm refl. VSNET 1995 07 30.888 13.0 mv AA Vanmunster, T. 35-cm refl. VVS 1995 07 30.914 12.7 mv AA Broens, E. 35-cm refl. priv(BRO) 1995 07 31.653 13.2 mv Makiguchi, N. 25-cm refl. VSNET 1995 07 31.890 12.7 mv AA Diepvens, A. 16-cm refr. priv(DIE) 1995 07 31.896 12.8 mv AA Pietz, J. 40-cm refl. VSNET 1995 07 31.897 12.7 mv KA Pietz, J. 40-cm refl. VSNET 1995 07 31.921 13.0 mv AA Vanmunster, T. 35-cm refl. VVS 1995 08 01.914 13.1 mv AA Vanmunster, T. 35-cm refl. VVS 1995 08 03.058 13.1 mv AA Vanmunster, T. 35-cm refl. VVS FX Cep [UGSS?, 15.0p - 17.5p] ============================= Quickly after the outburst announcement in CVC 49, T. Kato and the Ouda Team, Kyoto University, Japan, supplied following addtionial information on FX Cep: "We have just confirmed the reported outburst of FX Cep at Ouda Station, Kyoto University. The object looks as bright as V~14.6. Judging from the quick-look images, the outbursting object seems to be the NE faint close companion to the object marked in the chart of Downes & Shara (1993). We are now trying to get a series of CCD photometry to check short-term variablity." Taichi Kato furthermore communicated some historical data on FX Cep : "We can supply some additional information from the discovery paper (Rosino 1962, Asiago. Contr. 132). FX Cep = GR 95 was observed in outburst rather frequently as extracted from this paper. The short recurrence time (shortest = 11 days) and the existence of a long outburst might be a hint of an SU UMa-type dwarf nova." Contrary to this first assumption, no superhumps were detected by the Ouda team : "FX Cep was observed at Ouda Station (Kyoto University) for 2.5 hours in order to check if there is any periodic modulation like superhumps. Although QPO-like short-term variation with a typical amplitude of 0.03 mag and a period ~10 min was detected, the results were negative for superhumps." ----------------------------------------------------------------------- DATE (UT) MAGN MS SEQ OBSERVER REMARKS SOURCE ----------------------------------------------------------------------- 1995 07 24.940 [15.4 mv GSC Vanmunster, T. 35-cm refl. VVS 1995 07 24.969 [15.0 mv GSC Poyner, G. 40-cm refl. CVC 49 1995 07 25.943 [15.0 mv GSC Poyner, G. 40-cm refl. CVC 49 1995 07 30.941 14.8 mv GSC Vanmunster, T. 35-cm refl. CVC 49 1995 07 30.958 14.5 mv GSC Broens, E. 35-cm refl. CVC 49 1995 07 31.059 14.5 mv KA Biesmans, M. 28-cm SCT priv(BIE) 1995 07 31.682 14.8 CV GSC Kato, T. 60-cm refl. VSNET 1995 07 31.924 14.8 mv GSC Vanmunster, T. 35-cm refl. VVS 1995 08 01.009 14.5 mv KA Pietz, J. 40-cm refl. VSNET 1995 08 01.029 14.6 mv KA Biesmans, M. 28-cm SCT priv(BIE) 1995 08 01.780 14.7 CV GSC Kato, T. 60-cm refl. VSNET 1995 08 01.976 14.8 mv GSC Vanmunster, T. 35-cm refl. VVS FN And [UG, 13.5p - 17.5p] ========================== Monitoring of FN And is still ungoing, and results in following addi- tional photometric observations : ----------------------------------------------------------------------- DATE (UT) MAGN MS SEQ OBSERVER REMARKS SOURCE ----------------------------------------------------------------------- 1995 07 26.019 13.8 mv TA *Broens, E. 35-cm refl. priv(BRO) 1995 07 26.930 13.8 mv TA *Szabo, R. 45-cm refl. priv(FID) 1995 07 26.930 14.0 mv TA *Fidrich, R. 45-cm refl. VSNET 1995 07 27.91 13.9: mv TA *Fidrich, R. 45-cm refl. priv(FID) 1995 07 30.933 [14.1 mv TA *Vanmunster, T. 35-cm refl. VVS 1995 08 03.059 [14.8 mv TA *Vanmunster, T. 35-cm refl. VVS Tonny Vanmunster