------------------------------------------------------------------- THE ASTRONOMER Electronic Circular No 1082 1996 May 25 14.25UT Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise, Basingstoke, Hants, RG22 4PP,England. Telephone/FAX(0256)471074 Int:+44256471074 INTERNET: GUY@TAHQ.DEMON.CO.UK GMH at AST.STAR.RL.AC.UK WORLD WIDE WEB http://www.demon.co.uk/astronomer ------------------------------------------------------------------- SUPERNOVA 1996aa IN NGC 5557 Wayne Johnson, Anza, CA, reports his discovery of a supernova (mag about 17) on two CCD image exposed on May 16 UT. The new star is located about 5" northwest the centre of NGC 5557 (R.A. = 14h18m.4, Decl. = +36o30', equinox 2000). SN 1996aa is not present on a Carnegie Atlas print or on a slightly-out-of-focus CCD image taken by Johnson in 1995. There is a foreground star of mag about 15 located on the opposite side of the galaxy, about 15" south-southeast from the galaxy nucleus. IAUC 6403 SUPERNOVA 1996ab IN ANONYMOUS GALAXY J. Mueller reports her discovery of a supernova (mag about 18.5) located at R.A. = 15h21m09s.0, Decl. = +27o55'23" (equinox 2000.0), which is 10" west and 15" north of the centre of a galaxy evidently identified as Abell 2065-356 by Postman et al. (1988, A.J. 95, 267), but which apparently is not the host galaxy (see report by Garnavich et al., below), a conclusion supported by N. Reid's finding that there is extended emission underlying SN 1996ab that is apparently not connected with the larger system. SN 1996ab was found on a IIIa-J plate taken by K. M. Rykoski and J. D. Mendenhall on May 12 UT with the 1.2-m Oschin Schmidt telescope in the course of the second Palomar Sky Survey. No object appears at the position of SN 1996ab on original Sky Survey prints; Reid further reports that there is no object at this position on Sky Survey plates exposed in 1986 May and June. P. Garnavich, A. Riess, P. Challis, and R. Kirshner, Harvard- Smithsonian Center for Astrophysics, write: "Spectra obtained by P. Berlind with the 1.5-m Tillinghast telescope on May 22.4 UT show that this is a type-Ia supernova near maximum light. The Si II 635.5-nm absorption is observed at 692 nm, which implies a redshift of z = 0.13 for the supernova (assuming an expansion velocity of 10 000 km/s). SN 1996ab is probably not associated with the Abell Cluster 2065 (z = 0.06), but rather with a fainter galaxy background to the cluster." IAUC 6405 SUPERNOVA 1996ac IN ANONYMOUS GALAXY R. H. McNaught reports his discovery of an apparent supernova on a U film taken on May 21.4 UT by K. S. Russell with the U.K. Schmidt Telescope, at which time SN 1996ac was fainter by about 1 mag than on May 9.5, when its magnitude was about 16.5 on a similar exposure taken by M. J. Drinkwater. SN 1996ac is located at R.A. = 12h24m11s.24, Decl. = +1o24'14".7 (equinox 2000.0), which is 2".2 west and 3".2 north of the galaxy's centre. A nearby star (mag about 17.5) has position end figures 13s.78, 23'46".6. No star appears at the position of SN 1996ac on an I survey plate taken on 1991 Apr. 6, nor is anything present on a Palomar Sky Survey B film taken on 1992 Apr. 7. IAUC 6406 (extract) V632 CYGNI (Q1996/030) Gary Poyner, Birmingham, UK reports an outburst of V632 Cygni. On May 13.052UT he estimated it at mag 13.9. Although the outburst was confirmed by Lasse Jensen, Denmark, details of the actual result have only just been received: May 13.986UT, 14.9. Guy M Hurst