BELGIAN ASTRONOMICAL SOCIETY V.V.S. - Working Group Variable Stars Cataclysmic Variables Circular No.16 1994, September 12 Ed.: T. Vanmunster, Walhostraat 1A, 3401 Landen, BELGIUM Internet: tvm@lms.be TEL. 32-11-831504 P. Van Cauteren, de Borrekenslaan 54, 2630 Aartselaar, BELGIUM 73064.1123@compuserve.COM TEL. 32-3-8774098 =================================================================== HT Cas [UGSU, 10.8v - 18.4v] ============================ We have been informed by Dave York, Abiquiu, NM, about a minor brightening of HT Cas. His visual observations indicate the variable has already started to fade again. Affirmative observations are highly encouraged. 1994 09 04.544 UT, [17.3 (M. Iida, Nagano, Japan, 0.16-m refl. + ST-6 unfiltered); 05.531 UT, [15.9 (M. Iida, 0.16-m refl. + ST-6 unfiltered); 06.988 UT, [15.9 (G. Poyner, Birmingham, UK, 0.40-m refl.); 08.527 UT, [16.0 (M. Iida, 0.16-m refl. + ST-6 unfiltered); 09.149 UT, 15.7 (D. York, 0.45-m refl., seq AAVSO); 10.173 UT, 16.0 (D. York); Similar minor brightenings (or small amplitude outbursts) have been noticed as early as 1947 by the discoverer of this dwarf nova, Hoffmeister. The most recent minor brightening was reported in 1993, according to our records. A detailed discussion of the behaviour of HT Cas in quiescence is given in [1]. V635 Cas [XR, 13.5 - 16.3V] =========================== Gary Poyner, Birmingham, UK reports that V635 Cas (an X-ray Be-NS binary) has started an optical outburst. Confirmation has come from Tonny Vanmunster, Landen, Belgium. Some selected observations are presented below. This star had a 3 year outburst periodicity between 1971 and 1991. Between 1969 and 1971, the periodicity was about 180 days, and there are some indications this short term outburst mechanism might be returning [2]. Since professional astronomers are monitoring this variable for x-ray enhancements (using a/o the GRO), this object should be part of each CV observation programme. Please keep on submitting your observations, and clearly mention the sequence reference. 1994 08 02.063 UT, 15.3 (G. Poyner, 0.40-m refl., seq TA); 08 13.045 UT, 14.8: (T. Vanmunster, 0.35-m refl., seq TA); 08 17.981 UT, 15.1 (G. Poyner); 08 29.967 UT, 15.3 (G. Poyner); 09 02.019 UT, 14.7 (G. Poyner); 09 02.034 UT, 14.3 (T. Vanmunster); 09 02.040 UT, 14.5 (G. Poyner); 09 06.976 UT, 14.5 (G. Poyner); 09 08.874 UT, 14.5 (G. Poyner, 0.30-m refl., seq TA); DM Lyr [UG, 13.6p - 18p] ======================== Referring to the announcement in CVC No.15, we have been informed that L. Szentasko, Veresegyhaz, Hungary made an independent detection of the outburst on Sept. 6.844 UT, using a 0.33-m reflector. The table below contains final photometric observations covering the present outburst. ------------------------------------------------------------------------ DATE (UT) MAGN MS SEQ OBSERVER REMARKS SOURCE ------------------------------------------------------------------------ 1994 09 02.856 [14.8 mv AA Vanmunster, T. 35-cm refl. VVS 1994 09 05.943 15: mv AA Broens, E. 35-cm refl. VVS 1994 09 06.844 14.3 mv * Szentasko, L. 33-cm refl. Mail(tep) 1994 09 06.924 14.6 mv TA Poyner, G. 40-cm refl. Mail(poy) 1994 09 07.566 14.9 mv * Takahashi, S. 60-cm refl. Mail(kat) 1994 09 07.601 14.6 mv * Moriyama, M. 33-cm refl. Mail(kat) 1994 09 07.870 14.5 mv AA * Vanmunster, T. 35-cm refl. VVS 1994 09 08.523 15.5 CU * Iida, M. 16-cm refl. Mail(kat) 1994 09 08.872 15.0: mv TA * Poyner, G. 30-cm refl. Mail(poy) 1994 09 09.529 [14.9 mv * Takahashi, S. 60-cm refl. Mail(kat) 1994 09 10.578 [15.1 mv * Takahashi, S. 60-cm refl. Mail(kat) V1113 Cyg [UGSU, 14p - <17p] ============================ Following the outburst announcement in CVC No.14, we received an email from Laslo Szentasko, Veresegyhaz, Hungary informing us that he made an outburst observation of this dwarf nova on August 7, 1993 (mag 13.6). This might thus constitute the first ever visual observation of V1113 Cyg. Further observations of the present outburst are summarised in the table below. ------------------------------------------------------------------------ DATE (UT) MAGN MS SEQ OBSERVER REMARKS SOURCE ------------------------------------------------------------------------ 1994 09 06.965 13.7 mv * Poyner, G. 40-cm refl. Mail(poy) 1994 09 06.84 13.9 mv VJ * Szentasko, L. 33-cm refl. Mail(tep) 1994 09 07.883 14.0 mv VJ * Vanmunster, T. 35-cm refl. VVS 1994 09 11.130 14.3 mv VJ * Vanmunster, T. 35-cm refl. VVS VJ = VSOLJ sequence (T. Kato) dd. 94.09.02 (frame DP92637). UZ Boo [UGWZ, 11.5v - 20.4V] ============================ The brightening of UZ Boo, reported by Bill Worraker on Sept. 5.87 UT (see CVC No.15), has been confirmed by other observers. Three nights later, the dwarf nova had already faded below mag 14.4, but once again rose on Sept. 10.13 UT, as shown by the observations of Dave York. Such mini-outbursts have been seen in other UGSU stars. VY Aqr showed such an event 22 days after the beginning of a superoutburst [3]. WZ Sge appears to have shown a similar event about 30 days after the superout- burst began, in all three of its recorded eruptions [4]. Recently, also T Leo has shown this behaviour [4,5]. The origin of this phenomenon is not known, so a close watch on light curves for brightenings of this type is most desirable. ------------------------------------------------------------------------ DATE (UT) MAGN MS SEQ OBSERVER REMARKS SOURCE ------------------------------------------------------------------------ 1994 08 27.840 13.3 mv AA * Schmeer, P. 20-cm SCT priv(sch) 1994 08 30.843 13.4 mv AA * Schmeer, P. 20-cm SCT priv(sch) 1994 09 01.898 13.3 mv AA * Schmeer, P. 20-cm SCT priv(sch) 1994 09 02.924 [13.5 mv AA * Schmeer, P. 20-cm SCT priv(sch) 1994 09 03.898 13.8 mv AA * Schmeer, P. 20-cm SCT priv(sch) 1994 09 06.437 13.5 CV GS * Ouda Team 60-cm refl. Mail(nog) 1994 09 06.791 14.0 mv AA * Szentasko, L. 33-cm refl. Mail(tep) 1994 09 08.858 [14.4 mv AA * Poyner, G. 30-cm refl. Mail(poy) 1994 09 09.473 [13.6 mv * Takahashi, S. 60-cm refl. Mail(kat) 1994 09 10.131 13.5 mv AA * York, D. 45-cm refl. priv(yor) 1994 09 10.156 13.5 mv AA * York, D. 45-cm refl. priv(yor) 1994 09 10.179 13.5 mv AA * York, D. 45-cm refl. priv(yor) V344 Lyr [UGSU, 14.5p - <20p] ============================= Dave York, Abiquiu, NM reports an outburst of V344 Lyr, as indicated by the observations below. 1994 09 06.918 UT, [14.8 (G. Poyner, Birmingham, UK, 0.40-m refl.); 09.186 UT, 14.8 (D. York, 0.45-m refl., seq AAVSO); 10.190 UT, 15.2 (D. York); 10.576 UT, [14.8 (S. Takahashi, Shiga, Japan, 0.60-m refl.); The last outburst observation of V344 Lyr was made on August 1, 1994, by T. Vanmunster (see CVC No. 11). References: ----------- [1] Wenzel, W., Astron. Nachr. 308 (1987) I, 75 - 80. [2] Poyner G., 7 Sept 1994, private communication (extract from an email by D. Roussel-Dupre, Los Alamos National Laboratory, US). [3] Patterson, J. et al., 1993, PASP, 105, 69-77 [4] Lemm, K. et al., 1993, PASP, 105, 1120-1126 [5] Bortle, J., 1993, AAVSO CIRCULAR, 268 Tonny Vanmunster