Central Bureau for Astronomical Telegrams
IAUC 4837: 1987A; 1989 NA; Occn OF 28 Sgr BY TITAN
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Read IAUC 4838
Circular No. 4837
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM EASYLINK 62794505
MARSDEN or GREEN@CFA.BITNET MARSDEN or GREEN@CFAPS2.SPAN
SUPERNOVA 1987A IN THE LARGE MAGELLANIC CLOUD
M. Karovska, P. Nisenson and C. Standley, Center for Astrophysics;
and S. Heathcote, Cerro Tololo Interamerican Observatory, report: "New
measurements of the diameter of SN 1987A were made from speckle data
obtained at the CTIO 4-m telescope in 1988 Dec. (IAUC 4749) using a
35-nm bandpass centered at 551 nm. The diameters obtained at 657/7 nm
and 551/35 nm are 0".042 +/- 0".002 and 0".046 +/- 0".002, respectively.
The mean velocity of expansion calculated from these measurements is in
agreement with previously reported measurements (2850 km/s: IAUC 4604).
Reconstructed images from the 551/35 nm data reveal complex arclike
structures within 2" of the supernova. The images clearly show the
presence of a number of bright knots in the structures. These arcs are
very similar to those described by Crotts et al. (IAUC 4791) in CCD
images obtained in 1989 Mar. These images are suggestive of separated
concentric rings around SN 1987A and may be due to a light echo or
fluorescence from material located behind the supernova in two discrete
shells. These shells could be a result of episodic mass loss during the
red-supergiant stage of evolution of the progenitor star. If this
interpretation is correct, one would expect to observe a contraction of
the rings by the current epoch."
1989 NA
Continuation to the ephemeris on IAUC 4807 from the orbital
elements on MPC 14958:
1989 ET R.A. (1950) Decl. Delta r V
Aug. 22 20 36.95 -46 43.0 0.543 1.474 16.0
Sept. 1 20 48.21 -46 48.6
11 21 01.78 -45 52.7 0.668 1.524 16.7
21 21 17.11 -44 09.9
Oct. 1 21 33.52 -41 52.5 0.832 1.594 17.3
11 21 50.59 -39 10.5
21 22 07.95 -36 12.8 1.032 1.678 17.9
31 22 25.36 -33 05.3
Nov. 10 22 42.74 -29 53.1 1.269 1.773 18.5
20 22 59.99 -26 39.8
30 23 17.08 -23 28.0 1.538 1.875 19.0
OCCULTATION OF 28 SAGITTARII BY TITAN
Corrigendum. On IAUC 4806, for -7d03'42" read +7d03'42".
1989 August 19 (4837) Brian G. Marsden
Read IAUC 4838
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