Central Bureau for Astronomical Telegrams
IAUC 6612: 1997bn; 1997bo
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Circular No. 6612
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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SUPERNOVA 1997bn IN UGC 4329
Qiyuan Qiao, Weidong Li, Yulei Qiu, Yi Zhang, and Jingyao Hu,
Beijing Astronomical Observatory (BAO), on behalf of the BAO
Supernova Survey, report their discovery of a supernova in UGC 4329,
found on unfiltered CCD images taken on Apr. 3.6 and 4.5 UT with
the BAO 0.6-m reflector. The supernova brightened from mag 16.4 to
16.2 between the two dates. SN 1997bn is located at R.A. =
8h19m02s.3, Decl. = +21o11'01" (equinox 2000.0), which is 6".0 east
and 8".2 south of the galaxy's nucleus. Unfiltered CCD images of
the same field taken on Mar. 27.6 (limiting mag about 18.0) show no
star at the position of the supernova. A low-resolution spectrum
taken by Y.-q. Qu, Chinese University of Science and Technology;
and J.-y. Wei, D.-w. Xu, and W.-d. Li, BAO, on Apr. 4.7 with the
BAO 2.16-m telescope of Xinglong station shows this to be a type-II
supernova prior to optical maximum. Weak yet conspicuous hydrogen
Balmer lines are seen superimposed on a very blue continuum. The
He I 587.6-nm line is also present. The expansion velocity derived
from the P-Cyg profile of H-alpha is about 16 000 km/s. The
recession velocity of the host galaxy is about 6300 km/s, as
derived from the narrow H-alpha emission line.
SUPERNOVA 1997bo IN ANONYMOUS GALAXY
The BAO Supernova Survey also reports their discovery of
another supernova (mag about 16.1) on unfiltered CCD images taken
on Apr. 3.6 and 4.6 UT with the BAO 0.6-m reflector. SN 1997bo is
located at R.A. = 12h19m52s.6, Decl. = +7 43'50" (equinox 2000.0).
Prediscovery images yield the following magnitudes: Mar. 15, 15.9;
27, 16.1. No star was visible on an image taken on 1991 Jan. 27.
The supernova is several times brighter than the host galaxy. A
nearby star (R about 15.4) has position end figures 53s.01, 48".3.
A low-resolution spectrum, taken on Apr. 4.8 by J.-y. Wei, D.-w.
Xu, and W.-d. Li, and Y.-q. Qu, shows this to be a type-II
supernova, possibly at plateau phase. There are very strong
hydrogen Balmer lines, and the Ca II infrared triplet is also
present. There are some Fe lines at the blue end of the spectrum,
though it is difficult to discern them because of the medium
signal-to-noise ratio. The expansion velocity of the supernova
envelope is about 7000 km/s, as derived from the absorption minimum
of H-alpha. There is strong, narrow H-alpha and O I 557.7-nm
emission of the host galaxy on the spectrum, with the recession
velocity measured as about 3690 km/s.
(C) Copyright 1997 CBAT
1997 April 4 (6612) Daniel W. E. Green
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