Central Bureau for Astronomical Telegrams
IAUC 4336: 1987A
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Circular No. 4336
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
F. Makino, Institute of Space and Astronautical Science,
Tokyo, reports that the x-ray astronomy satellite Astro-C (Ginga)
has been looking in the direction of SN 1987A with the large-area
(0.45 m**2 effective) proportional counters and the all-sky monitor
since Feb. 25. As of Mar. 7 no significant x-ray flux had been
detected from SN 1987A to a crude upper limit of flux 4 milli-Crab
in the energy range 1-30 keV. A more accurate upper limit will be
reported after the collimator response has been calibrated. Daily
monitoring from Ginga (= 'Galaxy'), which was launched on Feb. 5,
will continue. The satellite is currently still undergoing extensive
in-orbit testing, but the aforementioned instruments, as well
as the gamma-ray-burst detector, are functioning normally.
J. Matthews, University of Western Ontario; and N. Suntzeff,
Cerro Tololo Interamerican Observatory, report: "Spectra (range
350-750 nm, resolution 0.25 nm) have been obtained each night since
Feb. 26 using the Cassegrain spectrograph/2D-Frutti on the CTIO 1-m
telescope, by M. Pastoriza, T. Storchi-Bergmann [this name was
given incorrectly on IAUC 4328 and 4334] and J. Matthews. The
spectrum continues to redden. Recent developments (during Mar. 5-
9, wavelengths in nm) include the following. (1) deepening of
absorption features at 483 (He I 492.2?), 520 and 574 (He I 587.6?).
(2) development of P Cyg features with broad absorption at 547 and
603 (C III 616.0?). (3) strengthening emission at 420. (4) emission
features superposed on the emission peak of the H alpha P Cyg
profile. (5) appearance and subsequent fading of an absorption
feature at 737. (6) appearance of an absorption feature at 460 on
Mar. 9. (7) broadening of the absorption at 483, also on Mar. 9.
The following velocities (in units of 10**3 km/s) are derived from
the Balmer absorption minima: Mar. 6.09 UT, H alpha = -11.7, H beta = -8.8,
H gamma = -8.3; H delta = -9.5; 7.04, -11.9, -8.2, -7.6, -9.5; 8.02, -11.3,
-7.9, -7.6, -8.8; 9.02, -11.9, -7.9, -8.5, -9.7. We note a strong
resemblance between the latest spectra of SN 1987A and one of SN
1959D taken about 1 month after discovery. Shelton and Madore (IAUC
4330) point out that the U-B vs. B-V patterns of SN 1987A and SN
1959D are similar, but that the rate of color change is much higher
in the former. The similarity between our spectra of SN 1987A about
10 days after 'maximum' and the one of SN 1959D > 36 days after
maximum is consistent with this finding."
1987 March 9 (4336) Brian G. Marsden
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