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IAUC 6497: 1996bo; 126P

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                                                  Circular No. 6497
Central Bureau for Astronomical Telegrams
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
Phone 617-495-7244/7440/7444 (for emergency use only)

     A supernova in NGC 673 has been discovered independently by
Weidong Li, Qiran Qiao, Yulei Qiu, and Jingyao Hu, Beijing
Astronomical Observatory (BAO), as part of the BAO Supernova Survey,
on CCD images taken on Oct. 18; and by Mark Armstrong, Rolvenden,
Kent, U.K. (communicated by G. M. Hurst, Basingstoke), on
unfiltered CCD images taken on Oct. 23.095 UT.  G. J. Garradd,
Loomberah, N.S.W., reports that SN 1996bo is located about 6" east
of the galaxy's nucleus at the following CCD position:  R.A. =
1h48m22s.80, Decl. = +11 31'15".8 (equinox 2000.0).  The BAO
observers note that their discovery was made on a 120-s exposure
with the 0.60-m reflector, while a 300-s exposure on Oct. 8 with
the same instrumentation showed no image at the position of SN
1996bo.  Armstrong notes that images taken on Sept. 11 and Oct. 12
also failed to show anything at this position.  Estimated
magnitudes for SN 1996bo:  Oct. 18, V about 16.5 (Li et al.);
23.468, R about 16.5 (Garradd).
     M. Turatto and S. Benetti, European Southern Observatory (ESO);
and M. Lemke, Sternwarte Bamberg, write:  "A spectrum (range 360-
740 nm, resolution 0.5 nm) taken on Oct. 24.10 UT with the ESO 1.5-
m telescope (+ Boller & Chivens spectrograph) confirms that this is
a supernova of type Ia, about 1 week before maximum.  Strong lines
of Si II, S II, Fe III, and Ca II are present, with minima measured
at 618.2, 585.0, 549.8, 534.0, 492.3, 434.0, 403.8, and 372.2 nm.
The photospheric expansion velocity, measured from the minimum of
the Si II doublet, is about 13 300 km/s, while that measured from
Ca II is about 22 000 km/s, making this object more similar to SNe
1992A and 1981B than to SN 1994D (Patat et al. 1996, 278, 111).
Strong interstellar Na I D absorptions are measured at 599.2 and
599.9 nm -- i.e., at the same recession velocity (about 5250 km/s)
of the narrow H-alpha, [N II] and [S II] emissions of the parent
galaxy.  On Oct. 24.14, the following magnitudes were measured with
the Dutch 0.9-m telescope: B = 16.32, B-V = +0.32, V-R = +0.27; and
the position of SN 1996bo was measured to be 5".3 east and 1".7
south of the galaxy's center."

     Total visual magnitude estimates: Oct. 8.22 UT, 12.4 (R. Keen,
Mt. Thorodin, CO, 0.32-m reflector); 11.91, 11.7 (J. Carvajal,
Madrid, Spain, 0.21-m reflector); 13.78, 12.3 (K. Sarneczky,
Raktanya, Hungary, 0.44-m reflector); 15.47, 11.8 (D. A. J.
Seargent, Cowra, N.S.W., 0.25-m reflector).

                      (C) Copyright 1996 CBAT
1996 October 24                (6497)            Daniel W. E. Green

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