January 15, 2002 - 7792
XTE J1550-564
XTE J1550-564
J. Swank, E. Smith, and C. Markwardt, Goddard Space Flight
Center, report: "Rossi X-Ray Timing Explorer observations indicate
that XTE J1550-564 is again at a flux of 50-100 mCrab, which it
reached in 2001 Jan. for about 3 weeks. Since 2001 Oct., the ASM
has indicated intermittent levels of a few ASM counts/s. In a
pointed observation on 2002 Jan. 10.875 UT, the PCA confirmed a
level 60 mCrab, with a very hard spectrum (power-law index 1.4 +/-
0.2, cutoff 30-60 keV), corresponding to a 2-50-keV luminosity of
3 x 10**36 erg/s at 2500 pc. The spectrum includes Fe K-shell line
emission, possibly in a reflection component, and about 10 percent
of the luminosity is in a component attributable to a disk. High-
amplitude fluctuations (33-percent rms) are again present, with
characteristic times of 20-100 s (cf. IAUC 7575). Based on recent
behavior, a full outburst is not likely; nevertheless, additional
RXTE observations are scheduled and coordinated observations at
other wavelengths are encouraged."
C. Bailyn, Yale University, adds: "YALO observations on Jan.
12.319 and 13.337 UT yield V = 18.36 and 18.33, respectively.
These values are near the peak optical flux from the last two
outbursts of this source."
If you have a question about RXTE, please send email to one of our
help desks.