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IAUC 6667: 1997cn; COMETS 6P/D'ARREST AND C/1995 Q1 (BRADFIELD); C/1995 O1

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                                                 Circular No. 6667
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
URL http://cfa-www.harvard.edu/cfa/ps/cbat.html
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SUPERNOVA 1997cn IN NGC 5490
     M. Turatto and S. Benetti, European Southern Observatory
(ESO); and C. Pereira and L. Da Silva, Observatorio Nacional, Rio
de Janeiro, report:  "Inspection of a fully-reduced CCD spectrogram
(range 354-741 nm, resolution 0.6 nm) obtained on May 22.13 UT with
the ESO 1.5-m telescope (+ Boller & Chivens spectrograph) at La
Silla confirms that SN 1997cn is a peculiar type-Ia supernova.  The
spectrum closely resembles that of SN 1991bg one day after maximum
(cf. Turatto et al. 1991, MNRAS 283, 1).  In particular, the
spectrum shows the broad absorption between 420 and 450 nm that is
attributed to Ti II.  The unusual profiles of S II 546.8-, 561.2-,
and 565.4-nm lines are also closely matched.  The expansion
velocity deduced from the minimum of the Si II 635.5-nm line is low
(v = 9400 km/s) in comparison to that of SN 1991bg at the same
phase.  From the spectrophotometry, we estimate V about 16.7 and
B-V about +0.9, corresponding to M_v(max) about -17.4 (Hubble
constant 75 km sE-1 MpcE-1).  Note that the parent galaxy is an
elliptical (as in the case of SN 1991bg), and there is no evident
signature of Na I D absorption.  Therefore, the faint absolute
magnitude and the red color are intrinsic."

     M. Abbott, Center for Extreme Ultraviolet Astrophysics,
Berkeley; and V. A. Krasnopolsky and M. J. Mumma, Goddard Space
Flight Center, NASA, report:  "We searched for soft-x-ray radiation
from comet 6P on 1995 Sept. 4-5 (r = 1.42 AU, Delta = 0.46 AU) and
from comet C/1995 Q1 on 1995 Nov. 6-7 (r = 1.50 AU, Delta = 1.26
AU).  The observations were made in the range 70-180 eV with the
Extreme Ultraviolet Explorer orbiting observatory.  We detected
comet 6P at a luminosity equal to 1.1 x 10E24 photons/s within an
aperture radius of 120 000 km.  No emission was detected from
C/1995 Q1, with an upper limit of 3 x 10E23 photons/s in the same

     Total visual magnitude estimates (naked eye unless otherwise
noted):  Apr. 23.82, -0.2 (M. V. Zanotta, Milan, Italy); May 1.87,
0.1 (R. J. Bouma, Groningen, The Netherlands); 6.83, 0.4 (Zanotta);
9.34, 0.4 (T. Lovejoy, Brisbane, Queensland); 16.08, 1.2 (G. W.
Kronk, Troy, IL); 20.09, 1.6 (Kronk, 7x35 binoculars); 22.09, 2.1:
(Kronk, 20x80 binoculars).

                      (C) Copyright 1997 CBAT
1997 May 22                    (6667)            Daniel W. E. Green

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