BELGIAN ASTRONOMICAL SOCIETY V.V.S. - Working Group Variable Stars Cataclysmic Variables Circular No.29 1995, March 03 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 =================================================================== UW Tri [N: 1983, 15p - <21p] ============================ Tonny Vanmunster, Landen, Belgium reports another important outburst discovery, which has been confirmed by Eric Broens, Mol, Belgium and Gary Poyner, Birmingham, UK. UW Tri, an object that is classified as a probable nova in 'A Catalog and Atlas of Cataclysmic Variables' [Downes, R.A., Shara, M.M., 1993, PASP, 105, 127-245], is in outburst ! It thus seems quite evident this is an UG-type cataclysmic variable instead of a probable nova. Photometry of the present outburst is of utmost importance ! 1995 03 01.815 UT, [15.1 (T. Vanmunster, 0.35-m refl., seq: GSC); 03 03.819 UT, 14.7 (T. Vanmunster); 03 03.828 UT, 14.7 (E. Broens, 0.35-m refl., seq: GSC); 03 03.833 UT, 14.9 (G. Poyner, 0.40-m refl., seq: GSC); We could find no references on UW Tri in professional literature. DV UMa = US 943 [UGSU:, 15.4v - 20.6v] ====================================== The rare outburst of DV UMa, followed by the rapid decline, seems to have attracted a lot of attention from the professional astronomers community. Among the received emails were some early reports on CCD- photometry results, that clearly illustrate DV UMa is one of the few known dwarf novae that show deep eclipses. The following is compilation of email received from T. Kato and D. Nogami, Ouda Station, Japan : "The Ouda team successfully obtained V-band photometry of four consecutive eclipses and three additional eclipses of the just-below-the-period-gap dwarf nova DV UMa. A least- squares fit to the observed times of the eclipses yielded a period of 0.08585 +/- 0.00001 day (the error includes the internal error only), which is significantly different from the published Porb (0.08579 day). The eclipse depth varied between 1.6 and 2.0 magnitudes (V) on February 27, 1995, and was 4 tot 5 magnitudes (V) on March 2, 1995". Kato further comments : "The light curves of DV UMa are the most striking ones we have ever obtained !" Nick James, Chelmsford, UK has used a 0.30-m f/5.25 Newtonian with a Sony CCD to obtain following accurate astrometry results on DV UMa : "RA = 9h46m36s.64, decl = +44g46'44".8 (2000.0), using 8 GSC stars with RMS residuals 0".21, 0".21. This is 2" W and 4" N of the position in 'A Catalog and Atlas of Cataclysmic Variables' [Downes, R.A., Shara, M.M., 1993, PASP, 105, 127-245]'." The table below lists observations covering the present outburst of DV UMa. The short duration of the outburst indicates this was a normal outburst. ----------------------------------------------------------------------- DATE (UT) MAGN MS SEQ OBSERVER REMARKS SOURCE ------------------------------------------------------------------------ 1995 02 22.845 [14.4 mv TA Vanmunster, T. 35-cm refl CVC 28 1995 02 25.844 [15.2 mv TA Poyner, G. 40-cm refl VSNET 1995 02 26.826 14.6 mv TA Vanmunster, T. 35-cm refl CVC 28 1995 02 26.840 14.7 mv TA Poyner, G. 40-cm refl CVC 28 1995 02 26.846 14.7 mv TA Broens, E. 35-cm refl CVC 28 1995 02 26.924 14.7 mv TA Vanmunster, T. 35-cm refl VVS 1995 02 27.510 15.0 CV Nogami, D. 60-cm+CCD VSNET 1995 02 28.712 15.7 CV Nogami, D. 60-cm+CCD VSNET 1995 03 01.432 15.9 CV Nogami, D. 60-cm+CCD VSNET 1995 03 01.55 15.8 CV Nogami, D. 60-cm+CCD VSNET 1995 03 01.806 15.3 mv Szentasko, L. 33-cm refl VSNET 1995 03 01.811 [15.2 mv TA Vanmunster, T. 35-cm refl VVS 1995 03 01.815 15.6 mv Szentasko, L. 33-cm refl VSNET 1995 03 01.831 16.0 mv Szentasko, L. 33-cm refl VSNET 1995 03 01.837 15.4 mv TA Broens, E. 35-cm refl CVC 28 1995 03 01.840 15.9 mv Szentasko, L. 33-cm refl VSNET 1995 03 01.851 15.6 mv Szentasko, L. 33-cm refl VSNET 1995 03 01.867 15.5 mv Szentasko, L. 33-cm refl VSNET 1995 03 01.889 [15.2 mv TA Vanmunster, T. 35-cm refl VVS 1995 03 02.083 15.5 mv Szentasko, L. 33-cm refl VSNET 1995 03 02.429 [15.5 CU Iida, M. 16-cm+ST-6 VSNET 1995 03 02.623 17.1 CV Nogami, D. 60-cm+CCD VSNET KV And [UGSU, 14.6p - 22.5p] ============================ The photometric summary below concludes our monitoring of the current outburst of this UGSU-type dwarf nova (see also CVC No.27). ----------------------------------------------------------------------- DATE (UT) MAGN MS SEQ OBSERVER REMARKS SOURCE ------------------------------------------------------------------------ 1995 02 18.872 [14.5 mv GSC Vanmunster, T. 35-cm refl VVS 1995 02 21.847 [14.5 mv Poyner, G. 40-cm refl VSNET 1995 02 21.885 14.7 mv GSC Vanmunster, T. 35-cm refl CVC 27 1995 02 21.890 14.8: mv Poyner, G. 40-cm refl CVC 27 1995 02 21.894 14.8 mv GSC Broens, E. 35-cm refl CVC 27 1995 02 25.811 15.1: mv Poyner, G. 40-cm refl VSNET 1995 02 26.882 [14.5 mv GSC Vanmunster, T. 35-cm refl VVS Tonny Vanmunster