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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