Circular No. 2822 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 Western Union: RAPID SATELLITE CAMBMASS A0620-00 C. J. Eyles, G. K. Skinner and A. P. Willmore, Department of Space Research, University of Birmingham, report the following position for the transient x-ray source A0620-00, obtained using the rotating modulation collimators on Ariel 5: R.A. = 6h20m15s, Decl. = -0o21'.2 (equinox 1950.0). The 90-percent confidence error radius is 3'. At the time of these observations (Aug. 19) the source was still extremely bright (approximately 20 000 Uhuru units). H. D. Craft, Jr., Arecibo Ionospheric Observatory, reports: "A weak radio source has been detected at the position of the x-ray source. The radio position is R.A. = 6h20m11s.7, Decl. = -0o19'30" (equinox 1950.0). Position errors are about 1' in both coordinates and enclose the x-ray and optical source positions (IAUC 2819). The source was detected at 2380 MHz on Aug. 15 and 19. At this frequency the source intensity showed no evidence of variability. Variability in excess of about 15 percent could have been detected. At 2380 MHz the radio source flux is 0.08 +/- 0.02 Jy. A detection of this same source at 1420 MHz has not yet been made convincingly; at 1420 MHz the flux density apparently is less than about 0.08 Jy." J. Lequeux, Director of the Radio Astronomy Department, Meudon Observatory, communicates: "A radio source has been detected with the Nancay radio telescope at 1408 MHz by L. Bottinelli, P. Encrenaz, L. Gouguenheim and R. Lucas in the direction of A0620-00. The Nancay beam is 21' in declination and was set at Decl. = -0o19' (equinox 1950.0). The measured right ascension of the radio source is R.A. = 6h20m12s +/- 2s. The radio flux density was 0.12 +/- 0.02 Jy on Aug. 20.33 UT and 0.11 +/- 0.04 Jy on Aug. 21.33 UT. There is a 0.33 Jy radio source following by 27s." Davis, Edwards, Morison and Spencer, Nuffield Radio Astronomy Laboratories, Jodrell Bank, report: "A radio source has been detected close to A0620-00. The flux density was 0.08 +/- 0.01 Jy at 962 MHz on Aug. 20. The position is R.A. = 6h20m11s.4 +/- 0s.27, Decl. = -0o17' +/- 7' (equinox 1950.0). There are no other compact radio sources stronger than 0.025 Jy within 4' of the SAS-3 position. Variability was less than 50 percent between Aug. 18 and 21." P. A. Feldman, Herzberg Institute of Astrophysics, reports that no point source stronger than 0.25 Jy (at the 3-sigma level) was found by G. Kojoian and C. R. Purton on Aug. 15.6 UT with the 46-m telescope of the Algonquin Radio Observatory at 10 600 MHz. 1975 August 25 (2822) Brian G. Marsden
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