Central Bureau for Astronomical Telegrams
IAUC 4584: 1987A; N Vul 1987
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Circular No. 4584
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
MARSDEN or GREEN@CFA.BITNET MARSDEN or GREEN@CFAPS2.SPAN
SUPERNOVA 1987A IN THE LARGE MAGELLANIC CLOUD
W. A. Mahoney, L. S. Varnell, A. S. Jacobson, J. C. Ling, R. G.
Radocinski and W. A. Wheaton, Jet Propulsion Laboratory, California
Institute of Technology, report: "A JPL high-resolution gamma-ray
spectrometer observed SN 1987A for 4.5 hours, centered on 1987 Dec.
6.64 UT, during a balloon flight from Alice Springs, Australia. The
prime sensor was a 220 cm**3 germanium detector with an energy
resolution of 2.7 keV FWHM at 1 MeV. Observation time was equally
split between source and associated background accumulations. A line
feature was observed in the net supernova spectrum at an energy of
1240.8 +/- 1.7 keV with an intrinsic width of 8.2 +/- 3.4 keV. We
interpret this as the 1238-keV line from the decay of 56Co in the
supernova remnant. The net line flux (in units of 10**-3 photons
cm**-2 s**-1) is 2.1 +/- 0.7. Measured emission in the 847-keV
56Co line, assuming a doppler broadening and energy shift
corresponding to those measured for the 1238 keV line, is 0.5 +/- 0.7
(same units). All errors are statistical."
W. R. Cook, D. Palmer, T. Prince, S. Schindler, C. Starr and E.
Stone, California Institute of Technology, report: "Hard x-ray and
gamma-ray observations of SN 1987A were made during the periods 1988
Apr. 12.0-12.5 and 13.0-13.3 UT with the Caltech Imaging Gamma-Ray
Spectrometer launched by balloon from Alice Springs. Preliminary
analysis of 5 hours of data yields a 4.9-sigma detection of flux in
the energy range 40-1300 keV from within 0.5 deg of the expected
position of the supernova. Comparison with data from a flight on 1987
Nov. 18 (IAUC 4527) indicates that the flux observed in the recent
flight is similar to that observed in the earlier flight with a
suggestion of a possible decrease in intensity. Preliminary estimates
of the continuum flux (in units of 10**-5 photons cm**-2 s**-1
keV**-1) now are 1.5 +/- 0.3 at 150 keV and 0.33 +/- 0.15 at 625 keV
(compared to 2.0 +/- 0.5 and 0.56 +/- 0.22 last November). The flux
estimate (in units of 10**-3 photons cm**-2 s**-1) for an energy range
94-keV wide centered on 847 keV is 0.8 +/- 0.4, and the 3-sigma upper
limit on flux fom a 93-keV-wide band centered on 1238 keV is 1.4."
Visual magnitude estimates by A. C. Beresford, Adelaide, South
Australia: Apr. 12.50 UT, 7.3; 14.42, 7.5; 15.41, 7.4; 16.47, 7.4;
20.41, 7.3; 21.44, 7.4; 22.45, 7.4.
NOVA VULPECULAE 1987
Visual magnitude estimates: Mar. 23.15 UT, 15.0 (A. Boattini,
Florence, Italy); 31.41, [15.0 (C. Scovil, Stamford, CT).
1988 April 23 (4584) Brian G. Marsden
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