Central Bureau for Astronomical Telegrams
IAUC 4735: SUB-Millisec OPTICAL PULSAR IN 1987A; 1989B
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Circular No. 4735
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
SUB-MILLISECOND OPTICAL PULSAR IN SUPERNOVA 1987A
J. Middleditch, Los Alamos National Laboratory; C. Pennypacker,
D. E. Morris, R. A. Muller, S. Perlmutter, and T. Sasseen, Lawrence
Berkeley Laboratory; J. A. Kristian and W.E. Kunkel, Mount Wilson and
Las Campanas Observatories; M. A. Hamuy, Cerro Tololo Interamerican
Observatory; J. N. Imamura, University of Oregon; T. Y. Steiman-Cameron,
Ames Research Center, NASA; I. K. Shelton, University of Toronto;
and I. R. Tuohy and S. Rawlings, Mt. Stromlo and Siding Spring
Observatories, communicate: "We report observation of an
optical pulsar in the supernova 1987A in the Large Magellanic Cloud.
Detection was made at the Cerro Tololo 4-m telescope on Jan. 18,
using a silicon photodiode with a sampling rate of 5 kHz. The
magnitude of the pulsed light from the supernova changed continuously
from mag 19 to 18 during a 7-hr period Jan. 18.1-18.3 UT. No
pulsations were detected during a subsequent observation taken
at the Las Campanas 2.5-m telescope on Jan. 31 in two 100-min runs
with an upper limit of mag 20. The frequency of the pulsar during
the Jan. 18 observation was tracked by dividing the data into
independent half-hour runs; the statistical significance during these
runs ranged from 11 to 37 standard deviations. The frequency exhibits
a sinusoidal modulation; the 15 frequency measurements were within
5 percent (rms) of a sine function with a central value of 1968.629
Hz (barycentric), amplitude 3 x 10E-3 Hz (peak-to-peak)
and period of 8 hr. Significant power was observed with the
same sinusoidal modulation at the aliased frequencies for both the
first and second harmonics."
SUPERNOVA 1989B IN NGC 3627
Visual magnitude estimates (visual unless otherwise indicated):
Jan. 28.20 UT, 13.5: (S. H. Lucas, Midlothian, IL; independent
discovery, not confirmed at the time); 29.11, 13.0 (A. Kane, Exeter,
England; independent discovery); 29.63, 13: (T. Yumine, Wakayama City,
Japan; prediscovery photograph on Fujicolor Super HG400 film);
31.46, 12.5 (D. Patchick, Culver City, CA); Feb. 1.96, 12.4 (G. M.
Hurst, Basingstoke, England); 2.29, 12.3 (R. Royer, Wrightwood, CA);
3.28, 12.1 (A. Hale, Las Cruces, NM); 4.64, 12.5 (A. Pearce,
Woodlands, W. Australia); 5.03, 12.2 (S. Korth, Duesseldorf, W.
Germany); 6.78, 12.1 (Pearce); 8.00, 12.3 (A. Boattini, Florence,
Italy); 8.97, 12.1 (J. D. Shanklin, Cambridge, England).
1989 February 8 (4735) Daniel W. E. Green
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