XTE J1550-564
Abstract
J. A. Tomsick, University of California at San Diego (UCSD); E. Smith and J. Swank, Goddard Space Flight Center; R. Wijnands, Massachusetts Institute of Technology; and J. Homan, University of Amsterdam, report: "Recent observations of the blackhole x-ray transient XTE J1550-564 with the Rossi X-ray Timing Explorer (RXTE) indicate that the source is active again. The last outburst ended in 2000 August, and a Chandra observation made on 2000 Aug. 16 indicated a flux level of 1 x 10**-13 erg cm**-2 s**-1 (0.5-8 keV). A 2.5-20-keV source flux of 9 x 10**-10 erg cm**-2 s**-1 was measured by RXTE on 2001 Jan. 28.7 UT. The spectral and timing properties indicate that the source is in the low-hard state. The energy spectrum can be described by a power law with a photon index of 1.52 and a neutral iron line with an equivalent width of 160 eV. The level of timing noise is about 40-percent rms (0.01-100 Hz; 2-60 keV), with violent flaring activity having a repetition period of 100-160 s. Currently, it is not clear if the observed activity will lead to a full outburst. Additional RXTE observations are scheduled, and coordinated observations at other wavelengths are encouraged."
R. Jain and C. Bailyn, Yale University; and J. Tomsick, UCSD, report YALO consortium observations of the optical counterpart of XTE J1550-564 using the Yale 1-m telescope (+ ANDICAM instrument) at Cerro Tololo Interamerican Observatory: "XTE J1550-564 has entered a new optical outburst. By Jan. 28.34, 29.34, and 30.34 UT, the object was at V = 18.28 +/- 0.01, 18.27 +/- 0.01, and 18.25 +/- 0.01, respectively. The source is significantly brighter than the quiescent level of V about 21.6."- Publication:
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International Astronomical Union Circular
- Pub Date:
- January 2001
- Bibcode:
- 2001IAUC.7575....2T