Central Bureau for Astronomical Telegrams
IAUC 4953: 1990B; 1989c1
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Circular No. 4953
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM EASYLINK 62794505
MARSDEN or GREEN@CFA.BITNET MARSDEN or GREEN@CFAPS2.SPAN
SUPERNOVA 1990B IN NGC 4568
M. A. Dopita and S. D. Ryder, Mt. Stromlo and Siding Spring
Observatories, report that observations on Jan. 23.70 UT using the
Double Beam Spectrograph on the Australian National University's 2.3-m
telescope show the supernova to be of type I. It is very heavily
reddened, with very little flux below 440 nm. The interstellar Na D
lines are prominent. The accurate position of the supernova was
determined to be R.A. = 12 34 02.2, Decl. = +11 30 59 (equinox 1950.0).
A. V. Filippenko, University of California at Berkeley, reports
that H. Spinrad and M. Dickinson, also of Berkeley, obtained a spectrum
(range 390-820 nm, resolution 1-3 nm) of SN 1990B on Jan. 23 UT with a
Cassegrain CCD spectrograph on the Shane 3-m reflector at Lick
Observatory. Filippenko has examined the unreduced data and concludes
that the object is of type Ib; the deep 620-nm trough typical of SNe Ia
is absent, and the spectrum closely resembles that of the type Ib SN
1987M several weeks past maximum. Helium absorption lines are weak or
absent, unlike the case in helium-rich SNe Ib, although some He I 587.6
nm might be blended with the strong, broad Na D absorption trough.
There may be a weak, broad component of H-alpha emission, fainter than
that in 1987K (Filippenko 1988, A.J. 96, 1941), but this must be verified
with fully reduced data. Narrow H-alpha emission is prominent, and
narrow interstellar Na D absorption is very strong; both are at the
approximate redshift of the host galaxy.
R. P. Kirshner and B. Leibundgut, Harvard-Smithsonian Center for
Astrophysics, report that a spectrum obtained by E. Horine on Jan. 24.4
UT at the Whipple Observatory is most consistent with a type Ib supernova
near maximum. The red spectrum shows strong absorption at 580 nm and only
a weak feature at 620 nm. The supernova was estimated at V about 14.5.
COMET AUSTIN (1989c1)
Total visual magnitude estimates: Jan. 14.45 UT, 8.8 (G. Garradd,
Tamworth, N.S.W., 10 x 50 binoculars); 15.45, 8.9 (Garradd); 17.56, 9.2
(A. Pearce, Scarborough, Western Australia, 20 x 80 binoculars); 18.50,
8.4 (T. Lovejoy, Melbourne, Victoria, 15 x 80 binoculars); 19.46, 8.3
(Lovejoy); 21.10, 8.9 (C. S. Morris, Whitaker Peak, CA, 0.26-m
reflector); 22.08, 8.9 (A. Hale, Las Cruces, NM, 0.41-m reflector);
23.48, 8.7 (Pearce, 20 x 120 binoculars); 24.50, 8.6 (Pearce).
1990 January 25 (4953) Brian G. Marsden
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