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IAUC 6408: 1996ad; C/1995 O1

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                                                  Circular No. 6408
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)

     G. J. Garradd and R. H. McNaught report the discovery by R.
Evans of an apparent supernova found on a U.K. Schmidt film taken
on May 9.56 UT by M. Drinkwater.  McNaught notes that the new star
is close to the galaxy's center (2" east, 1" north) and difficult
to see; he measured SN 1996ad (mag 18.5) on the discovery film:
R.A. = 15h59m05s.91, Decl. = +19o48'08".1 (equinox 2000.0).  L.
Germany (Mount Stromlo and Siding Spring Observatories) reports
that the new star is present at V about 18.5 on images taken with
the 1-m telescope on May 17.4.  A U.K. Schmidt film taken on May
25.6 by D. M. James and M. Hartley shows that SN 1996ad had faded
about 1 mag or more and is present only as an extension of the
nucleus to the northeast.  SN 1996ad is not present on earlier U.K.
Schmidt films taken on 1995 July 18 and Aug. 29.  McNaught further
notes that the host galaxy normally shows a near-stellar nucleus,
whereas at discovery there was clearly an additional stellar image
adjacent to the nucleus.  A foreground star (mag R = 19.0) is located
about 15" east and 5" north of the galaxy's center.

     L. M. Woodney, University of Maryland (UM); M. Womack and D.
Suswal, Pennsylvania State University; J. McMullin, Submillimeter
Telescope Observatory; M. F. A'Hearn, UM; M. Festou, Observatoire
Midi Pyrenees; and S. A. Stern, Southwest Research Institute,
report observations of H2S 1(10)-1(01) and CO J(2-1) from this
comet:  "H2S was detected for the first time in C/1995 O1 on May 21
UT at the NRAO 12-m telescope on Kitt Peak.  The line was 0.6 km/s
wide, had an integrated main beam brightness temperature of 0.10 K
km/s, and was blueshifted by 0.15 km/s.  Assuming a rotational
temperature of 30 K, we derive a production rate of Q(H2S) = 3.0 x
10E26 sE-1.  This detection was confirmed on May 23, when the line
was observed to be 0.7 km/s wide and have an integrated main-beam
brightness temperature of 0.17 K km/s.  The CO line observed on the
same day yields a production rate of Q(CO) = 4.0 x 10E28 sE-1,
which implies Q(H2S)/Q(CO) = 0.008."
     Visual m1 estimates:  May 18.54 UT, 7.2 (S. J. O'Meara,
Volcano, HI, naked eye); 21.04, 6.8 (M. V. Zanotta, Mount Generoso,
Italy, 7x42 binoculars); 24.78, 6.5 (T. Lovejoy, Jimboomba, Qld.,
Australia, naked eye); 26.10, 6.6 (J. Carvajal, Teruel, Spain,
10x70 binoculars).

                      (C) Copyright 1996 CBAT
1996 May 27                    (6408)            Daniel W. E. Green

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