THE ASTRONOMER Electronic Circular No 590 1991 Dec 23 17.44UT Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise, Basingstoke, Hants, RG22 4PP,England. Telephone/FAX(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 1991bg IN NGC 4374 M. Della Valle, J. Danziger, and C. Gouiffes, European Southern Observatory, communicate: "A CCD spectrogram (range 400-840 nm, resolution about 2 nm) of SN 1991bg was obtained on Dec. 15.4 UT with the 3.54-m New Technology Telescope (+ EMMI) at La Silla. The spectrum is dominated by strong absorptions of Si II (635.5, 597.2, 564.0, 545.4 nm) and Fe II (492.4 nm), indicating a type-Ia supernova. The expansion velocity deduced from the minima of the Si II 635.5-nm absorption is 10 200 km/s. Preliminary photometric measurements give V = 14.11 +/- 0.02 and B = 14.87 +/- 0.03. This implies E(B-V) about 0.7-0.9 and B(0) = 11.9 at maximum light if it is a normal type-Ia object. This compares with Bmax = 12.2 for SN 1957B in the same galaxy. Alverado and Wenderoth (IIT) report similar colours obtained from CCD photometry on the 0.90-m Dutch telescope for Dec. 16.3. If the SN is normal, all these measurements are consistent (within +/- 0.2 mag), with the age at Dec. 15 being 0-7 days past maximum and with significant reddening." IAUC 5408 Bill Worraker, Didcot reports a visual observation on 1991 Dec 18.26UT when he estimated it at mag 14.2 (0.26-m refl.). E-chart using FINDERS Version 2.3e: \\\\\\SN1991 bg in NGC 4374 = M84 S,110,10,S P,12h 22.5m +13 10' (1950) O,55,52,13.9,? -L,R,SN1991bg -S,SN/019.01 -G,54,47,260,210,350 -G,107,77,80,60,330 R,10.22,9,51,aa,R R,11.64,68,91,bb,R R,11.91,41,69,A,R R,13.02,37,16,B,R R,13.44,8,37,cc,R R,13.67,46,80,C,R R,14.26,46,87,J,R R,14.7,47,50,K,A R,15.1,43,11,L,B R,16.0,47,29,M,B M,13,62,94,89,97,89,37 M,14,16,104,17,91,22,24,41,36,48,102,92,57,103,68,108,82 M,15,5,102,28,50,35,21,43,38,45,49,47,40,101,77,53,12 M,15,53,4 M,14,54,42 -L,R,SN1957B E,32 ////// Drawn by Guy Hurst from photo by A.Young 1982 Mar 23 UV PERSEI Mike Gainsford, Burbage reports an outburst of this UG star: 1991 Dec 22.80UT, 13.0. This was confirmed by M.Mobberley (Cockfield) and G.Poyner (Birmingham): 1991 Dec 22.822UT, 12.3: (Poyner); 22.89, 12.7 (Mobberley) Guy M Hurst