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IAUC 5678: 1992bn; N Sco 1992; N Sgr 1992 No. 3

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                                                  Circular No. 5678
Central Bureau for Astronomical Telegrams
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM     EASYLINK 62794505

     Christian Pollas, Observatoire de la Cote d'Azur, reports his
discovery of an apparent supernova (mag about 19) on technical pan
films taken with the 0.9-m Schmidt telescope on Dec. 13.83 and
14.84 UT (limiting mag 21-22).  SN 1992bn is located at R.A. =
1h26m20s.50, Decl. = +8 53'24".8 (equinox 1950.0), or 1".2 east and
6".8 north of a galaxy of mag about 16.5 having end figures 20s.58,
31".6.  Nothing is visible either on a similar film taken in 1989
or on the Palomar Sky Survey prints.  A nearby star of mpg about 16
has end figures 26s.26, 48".0.

     R. H. McNaught, Anglo-Australian Observatory, reports that,
using the coordinates by Kilmartin and Gilmore on IAUC 5528, he
confirms the identification on the SERC J survey by Della Valle and
Smette (IAUC 5529) of the pre-nova as a star of mag about 18.
Examination of several films in B, J, R, and I show the star to be
blue with no evidence of variability.  Coordinates measured from a
J survey plate are R.A. = 17h03m42s.68, Decl. = -43 11'26".3 (equinox
1950.0; uncertainty 0".3 in each coordinate), in close
agreement with those on IAUC 5528.

     McNaught also reports that the following improved coordinates
were measured from three CCD frames taken by himself on Oct. 14 using
the Siding Spring 1.0-m telescope (the nova was better centered
with respect to field stars than were the frames of Oct. 13; cf.
IAUC 5635):  R.A. = 18h20m39s.40, Decl. -23 01'05".2 (equinox
1950.0, uncertainty 0".2 in R.A. and 0".5 in Decl.).  The pre-nova
has been identified as a blue star of mag about 20.5 on the SERC J
survey.  It is faintly visible on the SERC and ESO R surveys, but
not present on I survey plates.  These I plates show surrounding
stars that appear of similar brightness to the pre-nova on the J
plates.  Coordinates measured from one J plate have end figures
39s.38, 05".5 (uncertainty 0".3 in each coordinate, reduced using
the same 22 Hubble guide stars as for the CCD position above).
Nearby stars have end figures 39s.22, 07".6, mag 18; 39s.22,
11".5, mag 17.

1992 December 19               (5678)            Daniel W. E. Green

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