Central Bureau for Astronomical Telegrams
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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