New Outburst of X-ray Transient XTE J1856+053
ATel #1024; Alan M. Levine (MIT), Ron A. Remillard (MIT), and the ASM team at MIT and NASA/GSFC
on 8 Mar 2007; 19:42 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Alan M. Levine (aml@space.mit.edu)
Subjects: X-ray, Binary, Black Hole, Transient
Observations with the RXTE All-Sky Monitor reveal an outburst that is
consistent with being a new outburst of the previously detected
transient source XTE J1856+053 (Marshall et al. 1996, IAU
Circ. No. 6504; Barret et al. 1996, IAU Circ. No. 6519). The outburst
appears to begin on 2007 February 28 (1.5-12 keV intensity 23 +/- 6
mCrab) or March 1 (42 +/- 9 mCrab). The intensity rose steadily until
2007 March 5 when it was 69 +/- 4 mCrab. Through March 8, the intensity
has remained in the range 66-74 mCrab.
The ASM hardness ratios are HR1 (3-5 keV/1.5-3 keV) = 0.89 +/- 0.04 and
HR2 (5-12 keV/3-5 keV) = 0.37 +/- 0.06. These values indicate a soft
spectrum and thereby suggest the source is a binary system containing
a stellar-mass black hole.
