THE ASTRONOMER Electronic Circular No 573 1991 Oct 24 19.45UT Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise, Basingstoke, Hants, RG22 4PP, England. Telephone: (0256)471074 Int:+44256471074 Telex: 9312111261 Answerback: TA G JANET BOXES: GMH at UK.AC.CAM.ASTRONOMY.STARLINK or GUYH at UK.AC.SUSSEX.CLUSTER TELECOM GOLD: 10074:MIK2885 PRESTEL 256471074 ------------------------------------------------------------------- SUPERNOVA 1991bc IN UGC 2691 Robert H. McNaught, Anglo-Australian Observatory, reports his discovery of a supernova (mag about 16) on a J plate taken by M. Hartley with the U.K. Schmidt Telescope on Oct. 12.7 UT. The supernova appears in UGC 2691, in the arm connecting the two galaxies of this interacting pair, but much closer to the brighter, northern component. SN 1991bc is located at R.A. = 3h18m12s.92, Decl. = -1 13'33".0 (equinox 1950.0, uncertainty 0".3 in each coordinate); offsets from the center of the northern galaxy are 5" east, 6"south. No star of this brightness appears in this position on J or I survey films or on the Palomar Sky Survey. IAUC 5366 SUPERNOVA 1991bd IN UGC 2936 R. H. McNaught, Anglo-Australian Observatory, reports his discovery of another supernova on a V plate taken by M. Hartley with the U.K. Schmidt Telescope on Oct. 12.7 UT. The supernova (mag about 17) appears in UGC 2936 (= MCG +00-11-007), and is offset from the galaxy's center by 21" east and 30" north in a knot within a spiral arm. The position of the supernova is R.A. = 4h00m13s.98, Decl. = +1 50'11".1 (1950 uncertainty 0".6 in each coordinate). No star appears in this position on J or R survey films, nor on the Palomar Sky Survey. A nearby star of mag about 15 has end figures 10s.77, 49'31".5. IAUC 5367 EF PEGASI In response to an e-mail alert from TA, following the note on E570, Taichi Kato, Japan tells us that T.Takata and himself observed this variable on Oct 18 and discovered two superhumps at Oct 18.445 and 18.536 superimposed with strong 7-min quasi-periodic oscillations. They further advise that this dwarf nova is therefore an SU UMa type whose orbital period will probably be one of the longest known below the period gap. Further estimates by P.Schmeer: 17.999, 11.2; 19.767, 11.3; 21.790, 11.5. He adds that this is the first ever visually observed outburst. The nine previous outbursts were recorded photographically, the latest on 1982 July 14 cf IBVS 3209. MWC 560 Recent estimates show a fading is in progress: 1991 Sept 17.21UT, 9.6 (A.Pereira, Portugal); Oct 5.18, 9.8 (Schmeer); 11.18, 9.9 (Schmeer); 16.18, 10.3 (Pereira); 18.17, 10.5 (Schmeer). BZ UMA P.Schmeer reports an outburst of BZ UMa: 1991 Oct 19.17UT, [13.4; 21.072, 12.1 Confirmed by T.Kato, Japan: Oct 22 (19.40UT), 14.1 (CCD). Guy M Hurst