Central Bureau for Astronomical Telegrams
IAUC 4450: 1987A; 1986m; 1987h
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Read IAUC 4451
Circular No. 4450
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
M. Karovska, P. Nisenson, C. Papaliolios and C. Standley,
Center for Astrophysics, report: "The angular diameter of SN 1987A
has been determined at three wavelengths from high angular resolution
speckle data obtained on Apr. 2 and at four wavelengths from
data recorded on June 1. These dates were 38 and 98 days, respectively,
after the explosion. Observations were made with the CTIO
4-m telescope and our speckle camera using the PAPA 2-dimensional
photon-counting detector. Data were recorded in 10-nm passbands
centered at 450, 533 and 656 nm (H alpha) on both nights and at 775 nm
on June 1. Approximately 30 000 speckle frames were used in each
speckle integration for the SN data sets and the corresponding
comparison star data. The power spectra were first azimuthally
averaged, and then the SN power spectra were deconvolved with the
comparison-star power spectra. We performed a least-squares fit
of the Fourier transform of a uniform disk to the deconvolved SN
power spectra. On Apr. 2, at a wavelength of 450 nm, the angular
diameter was 0".010 +/- 0".003, which translates into a linear
diameter of 500 AU (at a distance of 50 kpc) and gives an expansion
velocity of 11 400 km/s; at 533 nm, angular diameter 0".011 +/-
0".004, linear diameter 550 AU, velocity 12 500 km/s; at 656 nm,
angular diameter 0".001 +/- 0".004. On June 1 the corresponding figures
were at 450 nm, 0".019 +/- 0".003, 950 AU, 8400 km/s; at 533 nm,
0".018 +/- 0".004, 900 AU, 8000 km/s; at 656 nm, 0".009 +/- 0".004, 450
AU, 4000 km/s; and at 775 nm, 0".022 +/- 0".005, 1100 AU, 9700 km/s."
Visual magnitudes by A. C. Beresford, Adelaide, S. Australia:
Sept. 15.41, 5.1; 16.47, 5.2; 17.47, 5.2; 18.41, 5.3; 19.50, 5.2.
PERIODIC COMET GRIGG-SKJELLERUP (1986m)
Total visual magnitude estimates: July 18.18 UT, 11.6 (A.
Hale, Las Cruces, NM, 0.41-m reflector); 19.25, 12.1 (C. S.
Morris, Lockwood Valley, CA, 0.26-m reflector); 25.19, 12.1
(Hale); 26.21, 12.4 (Morris).
PERIODIC COMET HOWELL (1987h)
Total visual magnitude estimates: July 25.77 UT, 12.8 (A.
Pearce and M. Clark, Perth, W.A., 0.32-m reflector); 26.43, 12.5
(Morris); Aug. 1.47, 12.8 (Hale); 28.44, 12.9 (Hale).
1987 September 19 (4450) Brian G. Marsden
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