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IAUC 3803: 1983e; Poss. SN IN NGC 4258

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                                                  Circular No. 3803
Central Bureau for Astronomical Telegrams
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
TWX 710-320-6842 ASTROGRAM CAM     Telephone 617-864-5758

     Y. Kozai, Tokyo Astronomical Observatory, telexes that
another bright new comet has been discovered by Sugano, Saigusa
and Fujikawa, each of whom described it as diffuse and
uncondensed. A further observation by B. Mayer, Barberton, OH,
mentions a condensation in a 2' coma, and a photograph by E.
Everhart, Denver, CO, shows a tail ~ 15' long.

      1983 UT         R.A. (1950.0) Decl.     m1    Observer

      May   8.757      1 34       +39 40      7     Sugano
            8.769      1 33.7     +39 27      7     Saigusa
            8.790      1 30       +39 30      7     Fujikawa
            9.38       1 34.0     +39 38      7     Mayer

     E. Hummel, Max-Planck-Institut fur Radioastronomie; J. M. van
der Hulst, Westerbork Observatory; R. D. Davies and A. Pedlar,
Jodrell Bank; and G. D. van Albada, Kapteyn Astronomical
Institute, report the discovery of a variable radio source in the
northern spiral arm of NGC 4258.  The source, which is located at
R.A. = 12h16m31s16, Decl. = +47deg36'08".3 (equinox 1950.0), was
detected in a 0.20-m VLA observation in Jan. 1982 at a level of 5.5 mJy.
A June 1979 VLA observation at 0.20-m (van Albada and van der Hulst
1982, A.Ap. 115, 263) does not show the source to a limit of 0.25
mJy.  An observation at 0.21-m with the WSRT made in late 1982
confirms the source at a flux of 3 mJy.  The source is either a
variable background source or a supernova: the latter is quite
likely because of the location.  If it is a supernova, it must
have appeared between late 1979 and late 1981.  Its strength is
~ 15 times that of Cas A and comparable to that of the
supernovae 1970G in M101 and 1980K in NGC 6946.

     P. Wild, Astronomical Institute, Berne University, informs us
that his inspection of the Zimmerwald supernova patrol films of
the area of NGC 4258 has revealed a star of mag 17 on 1981 Nov. 3.
Its position, R.A. = 12h16m31s33, Decl. = +47deg36'10".0 (equinox
1950.0), was 17" east and 76" north of the galaxy's nucleus and in
excellent agreement with the radio position reported above.

1983 May 9                     (3803)              Brian G. Marsden

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