Central Bureau for Astronomical Telegrams
IAUC 3632: 4U 1916-05; LMC X-4; 1980b
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Read IAUC 3633
Circular No. 3632
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 617-864-5758
4U 1916-05
S. Bowyer and J. Clarke, University of California at Berkeley;
and P. Henry, Harvard-Smithsonian Center for Astrophysics,
write: "We obtained a CCD direct image of the field of the x-ray burst
source 4U 1916-05 on June 26 with the 4-m Mayall telescope at Kitt
Peak. The limiting magnitude is R ~ 23, and at R ~ 23 there appears
a faint, point-source object within +/- 1" of the position indicated
on IAUC 3620. Two other stars appear on the edge of the
error circle, one 3" east and one 3" northwest; however, spectroscopy
of these stars with the 3-m Shane telescope at Lick shows
both to have late-type-star continua without high-excitation emission
lines. We therefore consider the R ~ 23 object to be the likely
optical counterpart of the x-ray source. The resulting value of
Lx/Lopt ~ 2 X 10**4, placing the source at the upper extreme of
measured x-ray to optical luminosities for x-ray bursters."
LMC X-4
R. L. Kelley, J. G. Jernigan, A. Levine, L. D. Petro and S.
Rappaport, Massachusetts Institute of Technology, write: "Analysis
of x-ray data obtained during a survey of the LMC in 1976 Feb. with
the rmc aboard SAS 3 has revealed the presence of an x-ray pulsar
with a period of 13.51 s. The four major LMC x-ray sources (LMC
X-1 to X-4) were 'on' and in the field of view during the 6-day observation;
however, the pulsations were detected with high statistical
significance only during the 40-min x-ray flare from LMC X-4
reported by Epstein et al. (1977, Ap.J. 216, 103). We therefore
identify LMC X-4 with the x-ray pulsar. The pulsed fraction is ~ 5
percent in the 2-11-keV energy band. A search for Doppler variations
in the pulsation period due to the 1.4-day binary orbit is
underway. In view of this development we urge optical observers to
obtain refined measurements of the optical Doppler velocity of the
companion star (Epstein et al. 1977, loc. cit.) and to search for
optical pulsations at the 13.5-s period."
COMET BOWELL (1980b)
A. Hale, San Diego, CA, writes that his visual observations
from Palomar Mountain (0.2-m reflector) on Aug. 2.19 and 19.17 UT
showed a faint, diffuse glow (m1 ~ 12, diameter ~ 1'.5) with some
condensation. The observations were difficult at low altitude.
1981 September 4 (3632) Brian G. Marsden
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