Central Bureau for Astronomical Telegrams
IAUC 4410: 1987A; N Sgr 1987; 1986m
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Circular No. 4410
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
W. Wamsteker, R. Gilmozzi and A. Casstella, ESA IUE Observatory;
and N. Panagia, Space Telescope Science Institute, report
for the European Target of Opportunity Team: "Recent observations
with the IUE have shown that an emission-line spectrum is developing
between 120 and 190 nm. The observations made on June 9, 10
and 13 clearly showed a flux increase shortward of 200 nm that is
caused mostly by the appearance of narrow emission lines, i.e.,
with widths from unresolved up to a FWHM of 2000 +/- 500 km/s. The
strongest lines (with tentative identifications given in parentheses)
are found at 124 nm (N V), 140 nm (Si IV, O IV), 149 nm (N
IV), 164 nm (He II) and 175 nm (N III). The presence of various
other lines is indicated in portions of the spectrum relatively
free of interstellar absorptions but cannot be confirmed yet. The
appearance of narrow lines in the ultraviolet spectrum may be due,
either to thinning out of the ejecta that are exposing the innermost
and hottest layers, or to the interaction of the supernova
ejecta with a dense shell created by wind material from the
progenitor and having a radius of some 500 AU. In this latter case,
one may expect to detect emission at both radio and x-ray
wavelengths. At wavelengths longer than 300 nm the flux continues to
decrease (IAUC 4399); the flux between 220 nm and 270 nm is nearly
constant, while the slow increase between 175 and 200 nm reported
earlier still persisted on June 13. The fes magnitude is fading
quite rapidly, in agreement with photometry reported on IAUC 4405."
Visual magnitude estimates: June 13.38 UT, 3.6 (D. A. J.
Seargeant, The Entrance, N.S.W.); 14.43, 3.5 (A. C. Beresford,
Adelaide, South Australia); 15.38, 3.6 (Beresford).
NOVA SAGITTARII 1987
P. Whitelock, South African Astronomical Observatory, reports
J = 8.82, H = 8.67, K = 8.33, L = 7.42 on June 12.938 UT. The
large K-L color may indicate emission features in the L band. She
adds that infrared spectroscopy is desirable.
PERIODIC COMET GRIGG-SKJELLERUP (1986m)
Total visual magnitude estimates by E. A. Jacobson, Evansville,
MN (0.25-m reflector): May 29.22 UT, 12.5; June 1.21, 12.7.
1987 June 15 (4410) Brian G. Marsden
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