Central Bureau for Astronomical Telegrams
IAUC 4743: 1987A; 1989B; R CrB
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Read IAUC 4744
Circular No. 4743
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
H. Ogelman, G. Hasinger, and W. Pietsch, Max-Planck-Institut
fur Extraterrestrische Physik; C. Gouiffes, J. Melnick, T. Augusteijn,
F. Gutierrez, P. Grosbol, and C. Santini, European Southern
Observatory; and H. Pedersen, Nordic Optical Telescope Scientific
Association, communicate: "We have observed SN 1987A at a 10-kHz
sampling rate with the ESO 3.6-m telescope on Feb. 15.06-15.25 and
16.08-16.17 UT with a range of filters covering the 0.4- to 0.9-
micron band in an attempt to detect the 1968.629-Hz periodicity
reported by Middleditch et al. (IAUC 4735). We see no significant
signal within 20 Hz of the reported frequency in any of the 30-min
averages of 17 Fourier transforms of 105 s. The implied upper limit
to the pulsed flux for each interval is about 8 magnitudes less than
the supernova itself. In a narrower search range, 1968.63 +/- 0.02
Hz, the 90-percent-confidence upper limit to the two-night average
of the pulsed flux is 9 magnitudes less than the supernova. For a
1-hr exposure with the V filter on Feb. 16.06, the limit is mag 20.3
in the above narrow frequency range. The Fourier spacing of all
transforms was about a factor of six larger than the amplitude of
the reported 8-hr sinusoidal modulation, thereby allowing long
averages without significant smearing of the signal. We are
continuing to monitor SN 1987A at the 10-kHz sampling rate to search
for other periodicities and the possible reappearance of the
submillisecond pulses."
SUPERNOVA 1989B IN NGC 3627
R. J. Lavery, Mt. Stromlo and Siding Spring Observatories,
reports the following CCD photometry of SN 1989B: Feb. 1.60 UT, R
= 12.0, B-R = +0.6; Feb. 2.60, R = 11.9, B-R = +0.7. The R
photometry is in the Cousins system.
R CORONAE BOREALIS
Visual magnitude estimates (cf. IAUC 4689): 1988 Dec. 13.20 UT,
10.5 (A. Boattini, Florence, Italy); 16.19, 10.7 (P. Schmeer,
Bischmisheim, West Germany); 30.15, 9.0 (Schmeer); 1989 Jan. 4.19,
9.0 (S. Korth, Dusseldorf, West Germany); 14.23, 8.5 (M. Verdenet,
Bourbon-Lancy, France); 19.1, 8.0 (A. Mizser, Budapest, Hungary);
23.06, 8.5 (Schmeer); 30.08, 8.9 (Boattini); Feb. 12.08, 7.9 (A.
Pereira, Cabo da Roca, Portugal); 15.97, 7.3 (J. D. Shanklin,
Cambridge, England); 16.97, 7.1 (Schmeer).
1989 February 24 (4743) Daniel W. E. Green
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