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IAUC 5276: NGC 6052; 1991b; 1989h1

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                                                  Circular No. 5276
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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
MARSDEN or GREEN@CFA.BITNET    MARSDEN or GREEN@CFAPS2.SPAN


NGC 6052
     Q. F. Yin and D. S. Heeschen, National Radio Astronomy Observatory,
report on further VLA observations of the variable radio source at R.A.
= 16 03 00.99, Decl. = +20 40 43.6 (equinox 1950.0), which is located in
the irregular galaxy NGC 6052 = Markarian 297 and was previously
discussed (Heeschen et al. 1983, Ap.J. 267, L73) in terms of supernova
activity.  The 6-cm flux density, which had increased from 2 mJy in 1980
Jan. to 12.4 mJy in 1982 Apr., had decayed to 1 mJy by 1990 Nov.  The
20-cm flux decayed from 14 mJy in 1983 Nov. to 4.2 mJy in 1990 July.
They add: "Radio lightcurves at 6 and 20 cm from observations obtained
in 1986, 1987 and 1990 indicate that the object is a very powerful
supernova, perhaps the most powerful supernova ever recorded.  Its
spectral luminosity at 6 cm is 6 x 10**28 erg s-1 Hz-1, eight times
greater than for SN 1986J.  We also report the discovery of another
variable radio source in the same galaxy at R.A. = 16 03 01.13, Decl. =
20 40 45.0 (equinox 1950.0).  Its 20-cm radio flux increased from 1 mJy
in 1986 July to 2 mJy in 1990 July.  The 20-cm radio spectral luminosity
in 1990 was about the same as that of SN 1986J at its peak.  This source
may also be a very powerful supernova."


COMET ARAI (1991b)
     Ephemeris continuation (cf. IAUC 5202) from the orbital elements on
MPC 18081:

     1991 ET      R.A. (1950) Decl.     Delta      r       m1
     May  24     9 07.70    +69 52.9    2.849    2.614    16.4
     June  3     9 40.67    +68 49.0
          13    10 12.22    +67 31.5    3.142    2.815    17.0
          23    10 42.06    +66 02.5
     July  3    11 10.08    +64 24.5    3.407    3.017    17.5
          13    11 36.35    +62 39.7
          23    12 01.04    +60 50.4    3.649    3.218    17.9
     Aug.  2    12 24.31    +58 58.8
          12    12 46.36    +57 06.8    3.872    3.418    18.3


PERIODIC COMET VAN BIESBROECK (1989h1)
     Total visual magnitude estimates by A. Hale, Las Cruces, NM (0.41-m
reflector): May 23.44 UT, 13.6 (involved with star); 24.45, 13.6.


1991 May 25                    (5276)              Brian G. Marsden

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