THE ASTRONOMER Electronic Circular No 521 1991 May 17 18.52UT 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 1991Z IN ANONYMOUS GALAXY R. H. McNaught, Anglo-Australian Observatory, reports his discovery, on a U.K. Schmidt Telescope R plate taken by S. M.Hughes on May 6.5 UT, of an apparent supernova (mag about 20) located at R.A.= 10h52m08s.11, Decl. = -3 56'28".7 (equinox 1950.0), which is 10".1 east and 4".5 north of the galaxy nucleus. No image appears at this position on J and R survey films. IAUC 5261 NOVA HERCULIS 1991 T. Kato and R. Hirata, Department of Astronomy, Kyoto University, report that CCD photometry with the 0.60-m reflector at Ouda station revealed 4 distinct eclipse-like fadings (amplitude 0.3 in V, duration 1.5 hr). The minima at Apr. 22.727, 27.785, May 3.738, and 4.631 UT are well represented by a period of 0.2976 day. IAUC 5262 H. Kosai, National Astronomical Observatory of Japan, reports the following approximate limiting magnitudes from color film exposed just prior to outburst: Mar. 23.75 UT,[11: (A. Yonezawa, Osaka); 23.80, [9: (E. Ueta, Kobe). IAUC 5265 SUPERNOVA 1991aa IN ANONYMOUS GALAXY R. H. McNaught, Anglo-Australian Observatory, reports his discovery of an apparent supernova (mag about 16) on an R plate taken by S. M. Hughes with the 1.2-m U.K. Schmidt Telescope on May 7.50UT. The supernova is located at R.A. = 12h42m34s.70, Decl. = -6 02'38".3 (equinox 1950.0), being offset from the galaxy nucleus by 13".2 east, 5".0 south, and situated at the end of the bar and at the start of a spiral arm. No star appears at this position on the SERC J or first Palomar surveys. IAUC 5263 SUPERNOVA 1991ab IN ANONYMOUS GALAXY C. Pollas, Observatoire de la Cote d'Azur, reports his discovery of an apparent supernova (mag about 19.5) in a spiral galaxy of mag about 16; SN 1991ab is located at R.A. = 13h56m59s.77, Decl. = +19 55'38".2 (equinox 1950.0), which is 8".1 east and 11".0 north of the galaxy's centre. The object was found on Tech Pan films --More-- taken by D. Albanese with the OCA Schmidt telescope on May 8.06 and 12.01 UT, the exposures having limiting magnitudes of about 22.5 and 22, respectively. Nothing is visible on the Palomar Sky Survey blue and red prints to mag about 21 and 20, respectively. IAUC 5267 Guy M Hurst