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IAUC 6763: 1997dn; CATACLYSMIC Var IN Cet; C/1997 D1

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                                                 Circular No. 6763
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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SUPERNOVA 1997dn IN NGC 3451
     G. M. Hurst, Basingstoke, England, reports the discovery of an
apparent supernova (mag about 16.0) by Tom Boles, Wellingborough,
on CCD frames taken during Oct. 29.177-29.217 UT as part of the U.K.
Nova/Supernova Patrol.  The star is also present at a similar
brightness on an image taken by Boles on Oct. 30.177.  N. D. James,
Chelmsford, provides the following astrometry for SN 1997dn from
Boles' discovery image:  R.A. = 10h54m18s.95, Decl. = +27o14'07".3
(equinox 2000.0), which is about 35" west and 20" south of the
center of NGC 3451.  No star is present at this location on a
master CCD image of NGC 3451 taken on 1997 May 31 by Boles.
     S. Jha, P. Garnavich, P. Challis, and R. Kirshner, Harvard-
Smithsonian Center for Astrophysics, report that a spectrum of SN
1997dn taken by P. Berlind at the Whipple Observatory 1.5-m
telescope on Oct. 30.5 UT indicates that it is a type-II supernova
after maximum.  A prominent P-Cyg profile of H-alpha is visible,
with a photospheric expansion velocity (measured from peak to
trough) of 6500 km/s.  Also present in the spectrum are H-beta,
H-gamma, He I (587.5 nm), and Fe II.  The redshift of the host
galaxy is 1300 km/s, measured from narrow H-alpha emission.

    The Beijing Astronomical Observatory (BAO) supernova survey,
with A. Esamdin, Urumqi Astronomical Station, reports their
discovery on Oct. 28, using the 0.6-m reflector at Xinglong Station,
of a cataclysmic variable star in outburst at R.A. = 0h27m27s.93,
Decl. = -1 08'26".8 (equinox 2000.0).  Available R magnitudes:  Oct.
17.64 UT, 14.5; 21.67, 14.9; 28.61, 15.4; 29.61, 15.6; 30.45, 15.8.
The variable did not apppear on CCD images obtained on Oct. 8
(limiting mag 18.5), and it appears as a very faint object on the
original Palomar Sky Survey.  A spectrum of the star, obtained by X.
Dong and Y. Zhao with the BAO 2.16-m telescope at Xinglong on Oct.
30.56, shows typical features of cataclysmic variables in outburst,
with mainly a blue continnum at 500-800 nm, and a spectrum at 380-
500 nm that is similar to the dwarf nova CY Lyr at maximum, with
absorption of H-delta, H-gamma, H-beta, and weak He I (447.1 nm).

     Visual m_1 estimates by K. Hornoch, Lelekovice, Czech Republic
(0.35-m reflector):  Sept. 29.12 UT, 12.7; Oct. 6.11, 12.3; 28.03,
11.9; 28.97, 11.8.

                      (C) Copyright 1997 CBAT
1997 October 30                (6763)            Daniel W. E. Green

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