Central Bureau for Astronomical Telegrams
IAUC 4352: 1987A
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Circular No. 4352
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 1987A IN THE LARGE MAGELLANIC CLOUD
N. Suntzeff and M. Hamuy, Cerro Tololo Interamerican Observatory,
report that SN 1987A remains in its plateau phase through
Mar. 22, having only brightened by 0.03 mag in B since Mar. 9, as
shown in the following preliminary photometry: Mar. 12.1 UT, V =
4.23, B-V = +1.46, U-B = +1.93, V-R = +0.54, R-I = +0.23; 14.1,
4.18, +1.49, +1.95, +0.62, +0.26; 15.1, 4.20, +1.52, +2.04, +0.59,
+0.25; 16.1, 4.18, +1.53, +2.08, +0.60, +0.28; 19.1, 4.12, +1.56,
+2.06, +0.65, +0.30; 20.1, 4.10, +1.60, +2.06, +0.66, +0.30; 21.1,
4.08, +1.61, +2.09, +0.68, +0.30; 22.1, 4.07, +1.61, +2.09, +0.69,
+0.30. VRI colors show a very linear increase in brightness, with
the redder colors increasing more rapidly. Since Mar. 4, 15 nights
of observations give the following changes in brightness (mag/day)
through Mar. 22: V, -0.021; R, -0.030; I, -0.039.
G. Testor and M.-C. Lortet, Observatoire de Paris, Meudon,
telex: "Two McMullan electronographic camera photographs, obtained
with the European Southern Observatory 1.5-m Danish telescope and
with H-beta (width 3.0 nm) and O III (width 1.0 nm) filters in 1982
Feb., indicate that Sanduleak -69 202 was composed of at least two
bright stars aligned north-south (within 1".0) and might even be a
cluster of stars."
J. B. Hearnshaw and J. Haar, University of Canterbury, report:
"From spectra obtained on the 0.61-m reflector at Mt. John Observatory,
we have measured the mean deceleration of the blue-shifted
absorption component of the H-alpha P-Cyg profile over the interval Mar.
4.43-21.35 UT, and find A = 356 +/- 20 km/s/day. This is about half
the mean deceleration in the interval Feb. 25.70-Mar. 4.43, where
we obtained 690 km/s/day with a large error bar (IAUC 4342). Velocities
of recent H-alpha absorption and emission peaks were (in 1000 km/s):
Mar. 18.336, -8.10, +0.46; 19.369, -8.00, +0.55; 20.333,
-7.70, +0.05; 21.354, -7.70, +0.18. There is a marked asymmetry of
the emission lines of H-alpha and also of emission features at 588, 502,
and 406 nm, with the peaks on the short-wavelength side of the
profile as a whole. The asymmetry has increased during Mar. 18-21.
The bump on the blue side of the H-alpha emission profile at 647 nm (cf.
IAUC 4350) has strengthened during Mar. 18-21."
Further visual magnitude estimates: Mar. 24.42 UT, 3.9 (D. A.
J. Seargent, The Entrance, N.S.W.); 24.42, 4.1 (A. Beresford,
Adelaide, S. Australia); 24.72, 4.1 (J. Campos, Durban, R.S.A.);
25.11, 4.0 (Campos); 25.40, 4.0 (Beresford).
1987 March 26 (4352) Daniel W. E. Green
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