------------------------------------------------------------------- THE ASTRONOMER Electronic Circular No 2645 2010 May 14 14.02UT Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise, Basingstoke, Hants, RG22 4PP,England.Telephone/FAX(01256)471074Int:+441256471074 INTERNET: GUY@TAHQ.DEMON.CO.UK Backup: gmh@wdcc1.bnsc.rl.ac.uk WORLD WIDE WEB http://www.theastronomer.org ------------------------------------------------------------------- VSX J213806.5+261957 (=NEW CATACLYSMIC VARIABLE IN PEGASUS) Further to TA E-Circulars 2643 and 2644, various images by Denis Buczynski, Martin Mobberley, Ernesto Guido and Guy Hurst have become available showing the object remains bright and well above the quiescent magnitude. On 2010 May 13 at 11h20mUT a job request from Hurst was executed with a short exposure on Sierra Stars 0.61-m-Cass and the V magnitude was 10.0. K. Kinugasa, Gunma Astronomical Observatory, reports on VSNET that a low dispersion spectrum of VSX J213806.6+261957 on 2010 May 8.65 with the GAO 1.5-m reflector (+GLOWS) was obtained. Following the report by Arai, the spectrum shows a strong H-alpha emission as well as H-beta and HeII (468.6nm). Also, the Bowen complex of NIII, CIII and CIV exists. These features resemble those of GW lib at early phase. The spectrum is at: http://www.astron.pref.gunma.jp/~kinugasa/otj2138_100508.gif. The normalized one by continum (roughly) is http://www.astron.pref.gunma.jp/~kinugasa/otj2138_100508_nor.gif. Rene Hudec, Astronomical Institute AS CR Ondrejov reports on 'The Astronomer's Telegram 2619' that the object was detected in the extended study of Sonneberg Observarory Archival Sky Patrol Plates (3000+plates analysed, taken 1928-2004). Another large optical outburst (peak on 1942 Nov 30) at mag =9.8B (+-0.5) was noted. The star was found in a superoutburst from 1942 Nov 30 till 1942 Dec 11, being fainter than mag 13B on 1942 Nov 10 and previously and also 1942 Dec 28 and thereafter. This limits the superoutburst duration to be between 12 and 46 days. The object was found to be fainter than mag 13-14B (limiting magnitude) on all other investigated plates confirming that the superoutbursts of this star are extremely rare. This gives a very long recurrence time of the superoutbursts, about 67 years, though other outbursts may not have been covered by this plate collection. The detection of another superoutburst confirms that VSX J213806.6+261957 is indeed a WZ Sge type dwarf nova, i.e. a short-period cataclysmic variable with a low accretion rate and very rare and large-amplitude superoutbursts. SUPERNOVAE 2010bb-2010bg These designations have been assigned to objects of magnitude 20 and fainter found during the Pan-Starrs1 Medium Deep Survey in 2010 Jan-Feb. SUPERNOVA 2010bh = GRB 100316D A spectrum of the afterglow of GRB 100316D shows some similarities to the SN 1998bw group of supernovae according to CBET 2227. SUPERNOVA 2010bi IN NGC 3509 Discovery by the CHASE Project of a possible supernova (CBET 2229): SN 2010 UT R.A. (2000.0) Decl. Mag. Offset 2010bi Mar 24.16 11 04 25.49 +04 50 17.6 17.7 28.4"E, 34.6"N SUPERNOVA 2010bj IN NGC 2357 Discovery by L. Cox and T. Puckett of a possible supernova (CBET 2230): SN 2010 UT R.A. (2000.0) Decl. Mag. Offset 2010bj Mar 28.11 07 17 43.21 +23 21 03.8 16.0 31.8"E, 19.4"S Guy M Hurst