BELGIAN ASTRONOMICAL SOCIETY V.V.S. - Working Group Variable Stars Cataclysmic Variables Circular No.63 1995, October 18 Ed.: T. Vanmunster, Walhostraat 1A, 3401 Landen, BELGIUM Internet: tvanmuns@innet.be TEL. 32-11-831504 =================================================================== TW Tri [UGZ, 13.3p - 17.0p] =========================== Tonny Vanmunster, Landen, Belgium has observed an outburst of this Z Cam type dwarf nova, which is part of the Belgian CVAP. Confirmative observations have been received from Charles Scovil (AAVSO) and Makoto Iida (VSOLJ). C. Scovil further adds that he has a photo of the field of TW Tri, taken on Oct 16, 1979, which shows the variable bright, perhaps about mag. 14.2. The following positive estimates are available : 1995 Oct 16.95 UT, 13.6 (T. Vanmunster, 0.35-m refl., seq: GSC); Oct 17.339 UT, 13.8 (C. Scovil, AAVSO); Oct 17.528 UT, 15.2 (M. Iida, 0.20-m refl.+ST-6, unfiltered); Oct 18.202 UT, 13.7 (C. Scovil, AAVSO, mag. between 13.6 and 13.8); Although TW Tri is classified as a UGZ-type dwarf nova, no standstills have been observed yet in this system, as fas as we know. It would be interesting to monitor this object in more detail, especially during the current outburst and the decline phase. TW Tri was last seen in outburst on August 3, 1995 (CVC 50), by Tonny Van- munster. PU Per [UG, 14.7p - 20:p] ========================= The outburst of PU Per, announced in our previous circular, was a faint and short one. The maximum magnitude (V=15.5), reported by Taichi Kato on October 13th (CVC 62), was later revised in a VSNET message (new value being V=16.5). Astrometric measurements by Makoto Iida, Nagano, Japan, on CCD images taken at Ouda Station, Kyoto University, Japan, have resulted in following accurate position of PU Per (J2000.0) : R.A.=02h42m16s.14, decl.= +35d40'46.4" (reference : 10 GSC stars, mean residual 0.1"). Taichi Kato, Ouda observatory, has been able to derive a rough period esti- mate of PU Per from photometric CCD observations : "From low-amplitude hump- like features (likely orbital humps during decline) in Oct. 13th observations, we have estimated a rough period of 0.058 +/- 0.002 day. If this modulation actually reflects the orbital motion, this dwarf nova is suspected to be a ultrashort orbital period SU UMa-type dwarf nova (WZ Sge-like object or extreme TOAD). The rate of decline supports this idea. The second outburst reported in Romano, Minello (1976, IBVS 1140) can be identified as a superoutburst." We conclude our monitoring of the present (normal) outburst of this interes- ting CVAP object, by listing the few available photometric observations : ----------------------------------------------------------------------- DATE (UT) MAGN MS SEQ OBSERVER REMARKS SOURCE ----------------------------------------------------------------------- 1995 10 13.532 16.6 CU GSC Iida, M. 20-cm + ST-6 VSNET 1995 10 13.549 17.0 CU GSC Iida, M. 20-cm + ST-6 VSNET 1995 10 13.714 16.5 CV GSC Ouda team 60-cm refl. VSNET 1995 10 14.556 [17.6 CU GSC Iida, M. 20-cm + ST-6 VSNET 1995 10 14.624 18.4 CV GSC Ouda team 60-cm refl. VSNET PV Per [UG, 14.9p - 20:p] ========================= On October 13th, 1995, Makoto Iida, Nagano, Japan reported an outburst of PV Per (another CVAP object), which subsequently has been confirmed by Taichi Kato and the Ouda team members of Kyoto University, Japan. It turned out to be a very faint and short outburst, characterised by a fast decline, as the photometric summary below indicates : ----------------------------------------------------------------------- DATE (UT) MAGN MS SEQ OBSERVER REMARKS SOURCE ----------------------------------------------------------------------- 1995 10 13.528 17.0 CU GSC Iida, M. 20-cm + ST-6 VSNET 1995 10 13.545 16.8 CU GSC Iida, M. 20-cm + ST-6 VSNET 1995 10 13.771 17.0 CV GSC Ouda team 60-cm refl. VSNET 1995 10 14.548 [17.2 CU GSC Iida, M. 20-cm + ST-6 VSNET 1995 10 14.631 18.9: CV GSC Ouda team 60-cm refl. VSNET The current outburst is in sharp contract with the previously observed one (see CVC 58 and CVC 59), which was much brighter and lasted substantially longer. It therefore is very likely that the September 1995 outburst was a superoutburst. CVAP UPDATE =========== We are once more extending the Cataclysmic Variables Alert Programme CVAP with a number of very interesting objects, which have been suggested to us by various sources. Each of them deserves a close monitoring. Note that some get bright enough to be spotted with relatively small telescopes. New CVAP objects are : VARIABLE RA DECL TYPE MAG_RANGE REMARKS NAME [2000.0] MAX MIN -------- ------------------------ ---- -------------- ------- NSV 786 02 22 21.1 +78 53 36. UG? 12p 14p [1,4,5] NSV 2872 06 14 10.6 +45 30 12. UG? 11.2p 14.5p [1,3,4,5] NSV 4838 10 23 18.7 +44 05 00. UG? 14.5p 16.5p [1,5] NSV 5543 12 18 38.4 +40 01 39. UG? 12p [14p [1,5] V630 CYG 21 34 59.31 +40 40 17.4 ugSU: 13.4p 17.2p [2] GD 552 22 50 39.75 +63 28 38.1 NL/UG? 16.5v [2,5] [1] Position from GCVS [2] Position from Downes and Shara (1993) [3] Might be not a CV [4] No references in Simbad Catalog [5] No visual observations listed in Vanmunster and Howell (1995) Finding charts and GSC-based sequences have been prepared for all new objects (except for V630 Cyg, for which we advise to use the AAVSO chart) and are available to observers upon simple request. Tonny Vanmunster