Circular No. 4532 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 F. Makino, Institute of Space and Astronautical Science, Tokyo, reports for the Ginga Team: "We have been monitoring the x- ray intensity of SN 1987A from Ginga. The flux values obtained so far are given below. These values are corrected for the energy- dependent detection efficiency of the Ginga detector, for aspect and for contributions of nearby sources. Errors include statistical errors as well as systematic errors due to the flux variation of LMC X-1 and also the background fluctuations. There follow for each date of observation the x-ray fluxes (units of 10**-12 erg cm-2) in two energy ranges 6-16 keV and 16-28 keV, respectively (errors given parenthetically): 1987 July 4, 12.6 (8.9), 24.7 (7.7); Aug. 3, 17.8 (3.3), 25.4 (7.6); Sept. 3, 21.7 (3.2), 32.0 (9.2); Sept. 28, 13.4 (3.4), 25.4 (9.5); Nov. 4, 21.7 (5.4), 36.6 (16.7); Dec. 10, 17.2 (3.8), 24.6 (9.1); Dec. 26, 9.3 (3.0), 29.4 (7.5); 1988 Jan. 7, 35.1 (4.5), 52.9 (10.8); Jan. 12, 46.6 (3.4), 53.5 (8.7)." Visual magnitudes by A. C. Beresford, Adelaide, S. Australia: Jan. 15.46 UT, 6.4; 16.50, 6.3; 17.46, 6.4; 18.47, 6.3; 19.50, 6.3. SUPERNOVAE 1987O AND 1987P C. Pollas, Caussols Observatory, reports revised magnitude estimates (cf. IAUC 4521, 4523, 4525) from photographic plates for SN 1987O: Dec. 20, 17.6 (15301 emulsion); Dec. 28, U [18.5; Dec. 29, B = 18.5. Magnitudes for SN 1987P: 19, 18.5, and 17.8, respectively. GX 339-4 W. B. Honey and P. A. Charles, Oxford University; J. R. Thorstensen, Dartmouth College; and R. H. D. Corbet, Institute of Space and Astronautical Science, Tokyo, report a periodic modulation in the brightness of the optical counterpart of the x-ray source GX 339-4 in its low state (IAUC 4383). The modulation has a period of 0.618 +/- 0.004 day (14.8 hr) and a half-amplitude of 0.20 +/- 0.04 mag in both the R and I bands. 283 usable CCD frames were obtained during 1987 July 18-30 with the CTIO 1.5-m and SAAO 1-m telescopes. Point-spread fitting techniques were used to deconvolve the x-ray star from its accidental companion. The 1986 June-July high-state data obtained by Corbet et al. (1986, MNRAS 227, 1055) corroborate the 0.62-day period. 1988 January 19 (4532) Brian G. Marsden
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