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
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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