Circular No. 3039 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION Postal Address: Central Bureau for Astronomical Telegrams Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. Cable Address: SATELLITES, NEWYORK Telex: 921428 Telephone: (617) 864-5758 X-RAY SOURCES M. Ricketts and B. A. Cooke, Leicester University, report: "The Ariel 5 sky-survey instrument has been observing flaring x-ray activity from a source in the region of 3U 0042+32. This is the first observation of this source by the ssi, although the source has been scanned for a total of 50 days since Nov. 1974, during which time the mean flux was less than 1.5 Uhuru cts/s. During 1977 Feb. 3-6 the flux was variable up to 25 Uhuru cts/s and during Feb. 14-17 up to 50 Uhuru cts/s. The 90-percent-confidence region is defined by R.A. = 0h42m, Decl. = +33o.5; 0h42m, +32o.6; 0h45m, +31o.5; 0h44m, +32o.2 (equinox 1950.0)." P. J. N. Davison, University College, London, writes that the Mullard Space Science Laboratory's experiment C on board Ariel 5 observed a turn-on of Her X-1 on Feb. 3d15h +/- 1h UT, the phase in the 1.7-day binary cycle being 0.28 +/- 0.02. R. H. Becker, S. H. Pravdo, J. R. Saba and P. J. Serlemitsos, Goddard Space Flight Center, report the discovery of an x-ray binary pulsator, consistent in position and intensity with 3U 1538-52. The source, detected by the cosmic x-ray spectroscopy experiment on OSO 8, has a pulsation period of 528s.96 +/- 0s.10 and a pulsed fraction of 0.5. Zero phase occurred on 1976 Aug. 25.8 +/- 10.1 UT. J. McClintock, F. Li, J. Nugent and S. Rappaport, Massachusetts Institute of Technology, report that the SAS-3 Group has discovered a 272s.2 +/- 0s.4 periodicity in the x-ray intensity of GX304-1 = 3U 1258-61. The source was observed during Feb. 14.8-21.9 UT and was variable with a mean 1-12 keV intensity ~ 0.02 that of the Crab Nebula. A prominent flare in the 1-12 keV intensity was observed to commence on Feb. 17.83328 UT; the duration of the flare was ~ 100s and the peak intensity > 3 times the ambient source intensity. W. H. G. Lewin, J. A. Hoffman and J. Doty, Massachusetts Institute of Technology, report that the SAS-3 Observatory has detected 23 x-ray bursts between Feb. 6 and 11 from within 1o.5 of the direction of the galactic center; this is a twofold increase over what was observed a year ago (IAUC 2918). A unique transient event, from a location at least 2o from the galactic center and having a brightness comparable to that of the Crab, was observed at about Feb. 7d20h01m25s UT. At low energies (1.3-5 keV) the risetime was 1s.5, and the decay took about 30 min; the hard x-rays (8-35 keV) were delayed by about 1.5 min, after which they rose to a maximum in an additional 2 min. The outburst was preceded by a precursor (simultaneously in the range 1.3-35 keV) of comparable brightness; the precursor started 9s before the onset of the main outburst at low energies and lasted only 4s. AN URSAE MAJORIS W. Krzeminski and K. Serkowski, Lunar and Planetary Laboratory, report that the circular polarization of the novalike object AN UMa varies between -9 and -34 percent in the blue spectral region of the UBV system, and the linear polarization varies between 0 and 11 percent. The circular polarization in U and V reaches -28 and -25 percent, respectively, halfway between the maxima of linear polarization. The polarization changes with the same period, 1h54m45s, derived from photometric observations by Shugarov and Mumford (1976 Inf. Bull. Variable Stars No. 1133). The object is similar to AM Her (IAUC 2994) and should be examined at x-ray wavelengths. POSSIBLE OPTICAL COUNTERPART FOR LMC X-4 V. M. Blanco, Cerro Tololo Interamerican Observatory, reports that observations by W. A. Hiltner lend support to the suggestion by Sanduleak and Philip (IAUC 3023) that the OB star 25" southeast of Pakull's candidate (IAUC 3017) is the one associated with LMC X-4. Approximate magnitudes and colors are V = 14.0, B-V = -0.1, U-B = -1.1. However, there are variations of 0.15 magnitude from night to night, possible variations of 0.05 magnitude in 3-4 hours and an observed brightening by 0.15 magnitude in minutes. SU TAURI Several observers have noted that the brightness of this R CrB variable is increasing. AAVSO Circ. No. 76 mentions brightening from magnitude 15 in the middle of January to 13.5 at the end. Recent visual estimates: Feb. 5.35 UT, 12.6 (C. E. Spratt, Victoria, British Columbia); 8.15, 13.0 (E. Mayer, Barberton, Ohio); 12.10, 12.9 (J. Bortle, Brooks Observatory); 16.02, 12.7 (Bortle). NOVAE V1500 Cyg. Correction to IAUC 3031, line 6: for 0d.130, read 0d.138. Visual magnitude estimate 12.4 on Feb. 10.99 UT (Bortle). NQ Vul. Visual estimates: Jan. 30.26 UT, 11.5 (G. M. Hurst, Northampton, England); Feb. 4.54, 11.5 (J. Morgan, Prescott, Arizona); 10.54, 11.4 (Morgan); 14.53, 11.4 (Morgan). Nova Sge 1977. Visual estimates: Jan. 30.2 UT, 10.9 (J. G. Hosty, Huddersfield, England); Feb. 2.54, 10.4 (Morgan); 6.54, 10.4 (Morgan); 10.54, 10.0 (Morgan); 14.53, 10.4 (Morgan). 1977 February 23 (3039) Brian G. Marsden
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