Central Bureau for Astronomical Telegrams
IAUC 4421: 1986G; 1987A; 1987j; 1986m
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Circular No. 4421
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
TWX 710-320-6842 ASTROGRAM CAM Telephone 617-495-7244/7440/7444
SUPERNOVA 1986G IN NGC 5128
B. Schaefer, Goddard Space Flight Center, writes: "Using the
0.91-m telescope (+ CCD) at Cerro Tololo Interamerican Observatory
on June 18.0 UT, I found SN 1986G at magnitude B = 19.80. This is
roughly 10 times brighter than the extrapolation of the lightcurve tail
based on either the observed decay rate (0.0188 +/- 0.0004 mag/day;
Phillips et al. 1987, preprint), the computed decay rate (0.020 +/-
0.003 mag/day; ibid.), or the average type-I SN decay rate (0.0152
+/- 0.0024; Dogget and Branch 1985, A.J. 90, 2303). This excess
brightness could be due to a light echo off dust in the dust lane
of NGC 5128. My calculations show that the light echo will dominate
the lightcurve at roughly 8 mag below the peak brightness if the 3.6
mag of extinction is within roughly 1 kpc of the SN. Observations are
needed to check the following predictions of the light echo hypothesis:
(1) the decay rate will now be very small, perhaps even 0.3
mag/yr; (2) the spectrum will now be that of the SN at maximum."
SUPERNOVA 1987A IN THE LARGE MAGELLANIC CLOUD
Further visual magnitude estimates: July 14.43 UT, 4.5 (R. H.
McNaught, Siding Spring Observatory); 15.37, 4.4 (A. C. Beresford,
Adelaide, S. Australia); 15.68, 4.6 (McNaught); 16.43, 4.7 (D. A.
J. Seargent, The Entrance, N.S.W.); 16.49, 4.6 (McNaught).
COMET TORRES (1987j)
Ephemeris extension from orbital elements on MPC 12 008:
1987 ET R. A. (1950) Decl. Delta r m1
July 24 12 06.44 - 9 12.1 4.053 3.745 13.8
Aug. 3 12 10.45 - 7 48.6
13 12 15.19 - 6 40.1 4.410 3.794 14.0
23 12 20.49 - 5 43.6
Sept. 2 12 26.23 - 4 56.2 4.696 3.850 14.2
PERIODIC COMET GRIGG-SKJELLERUP (1986m)
Total visual magnitude estimates (cf. IAUC 4411): June 26.39
UT, 11.8 (Seargent, 0.25-m reflector); 27.22, 11.6 (C. S. Morris,
Lockwood Valley, CA, 0.26-m reflector); 30.22, 11.5 (A. Hale, Las
Cruces, NM, 0.41-m reflector).
1987 July 16 (4421) Daniel W. E. Green
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