BELGIAN ASTRONOMICAL SOCIETY V.V.S. - Working Group Variable Stars Cataclysmic Variables Circular No.38 1995, May 22 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 =================================================================== T Leo [UGSU, 10B - 15.7B] ========================= T Leo is a dwarf nova, which is not included on the CVAP and Recurrent Objects Programme. It has been studied for a long time, and the behaviour of this cataclysmic variable seems to be well understood. However, recent publications [1,2] indicate that T Leo shows a remarkable phenomenon after certain outbursts : while returning to its minimum state, the dwarf nova briefly shows a secondary maximum ('mini-outburst'), which can be almost as bright as the primary outburst, but lasts for only one day or so. Such mini-outbursts have been seen in other UGSU stars as well. 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 superoutburst began, in all three of its recorded eruptions [1]. The origin of this phenomenon is not known, so a close watch on light curves for brightenings of this type is most desirable. Since there is considerable interest in a detailed study of this 'mini- outburst' behaviour in UGSU variables, we have decided to add T Leo to the CVAP, in an attempt to monitor a number of future outbursts intensively in order to detect and follow-up mini-outbursts. A first opportunity to detect mini-outbursts of T Leo might be well on its way. Patrick Schmeer, Bischmisheim, Germany just reported an outburst detection of T Leo. His observation has been confirmed by Tonny Vanmunster, Landen, Belgium and Eric Broens, Mol, Belgium, as follows : 1995 05 20.875 UT, [13.6 (P. Schmeer, 0.20-m SCT, seq: Huruhata); 05 20.958 UT, [13.6 (T. Vanmunster, 0.35-m refl., seq: AAVSO); 05 21.869 UT, 10.4 (P. Schmeer, 0.20-m SCT, seq: Huruhata); 05 21.910 UT, 10.2 (T. Vanmunster, 0.35-m refl., seq: TA); 05 21.933 UT, 10.4 (E. Broens, 0.35-m refl., seq: TA); The previous outburst of T Leo was seen on December 7, 1994 by Patrick Schmeer. The variable reached mag. 10.5 during that outburst. References: ----------- [1] Lemm, K. et al., 1993, PASP, 105, 1120-1126 [2] Bortle, J., 1993, AAVSO CIRCULAR, 268 [3] Patterson, J. et al., 1993, PASP, 105, 69-77 Tonny Vanmunster