Central Bureau for Astronomical Telegrams
IAUC 5686: 1989aa; 1992br and 1992bs
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Circular No. 5686
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@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)
SUPERNOVA 1989aa IN ANONYMOUS GALAXY
C. Pollas, Observatoire de la Cote d'Azur, reports his discovery
of a probable supernova of mag about 19.5 at R.A. = 1 16 33.46,
Decl. = +13 00 25.9 (equinox 1950.0), 1".5 west and 4".3 north of
the nucleus of an anonymous galaxy. The object was seen on technical
pan films (limiting mag 21-22) on 1989 Dec. 28.8 and 31.7 UT. Nothing
could be detected at the location on 1992 Dec. 13.8 and 14.8 UT.
SUPERNOVAE 1992br and 1992bs
J. Maza, University of Chile; and M. Hamuy, Cerro Tololo
Interamerican Observatory, report the discovery of two supernovae
on 20-min unfiltered IIa-O plates taken by G. Valladares with the CTIO
Curtis Schmidt telescope. SN 1992br, of mpg about 18.5, was discovered
by M. Wischnjewsky on an exposure on 1992 Dec. 27.09 UT and is 2".5 east
and 7" south of the nucleus of an anonymous galaxy at R.A. = 1 43 55.4,
Decl. = -56 20 57 (equinox 1950.0). SN 1992bs, of mpg about 18, was
discovered by L. Gonzalez on an exposure on Dec. 28.17 UT and is 9"
west and 4" north of the nucleus of an anonymous spiral galaxy at
R.A. = 3 27 37.2, Decl. = -37 26 38 (equinox 1950.0). The supernovae
were confirmed by R. Aviles on CCD B and V images (obtained on Dec. 30.19
and 31.23, respectively) with the CTIO 0.9-m telescope. Spectrograms
covering the wavelength range 320-750 nm, obtained on Dec. 31 with
the CTIO 1.5-m telescope, show in each case the characteristic Si II
(635.5 nm) feature of type Ia supernovae. The minimum of the Si II
absorption yields an expansion velocity (with respect to the parent
galaxy's rest frame) of about 10 000 km/s for SN 1992br and about
9300 km/s for SN 1992bs. Spectra of the nuclei of the parent
galaxies yield redshifts z = 0.088 and 0.064, respectively. Given
the low signal-to-noise ratio of the spectrum it is difficult to
estimate the age of SN 1992br accurately, but it is possible, from
comparison with the type Ia supernova 1992A, to state that this object
is not more than two weeks after maximum light. In the case of SN
1992bs, the spectrum shows absorptions of Si II (635.5, 564.0 and
545.4 nm) and only a moderate resemblance to the spectrum of the type
Ia supernova 1990N taken seven days before maximum light; no match
could be achieved between the spectrum of SN 1992bs and post-maximum
spectra of other type Ia supernovae.
1993 January 1 (5686) Brian G. Marsden
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