Bright New Black Hole Transient XTE J1817-330
ATel #714; R. Remillard, A. M. Levine, E. H. Morgan (MIT), C. B. Markwardt (U. Maryland & NASA/GSFC), & J. H. Swank (NASA/GSFC)
on 28 Jan 2006; 21:32 UT
Distributed as an Instant Email Notice Request For Observations
Credential Certification: Jean Swank (email@example.com)
Subjects: X-ray, Black Hole, Transient
Referred to by ATel #: 717, 721, 724, 731, 733, 734, 738, 740, 742, 749, 933
We report a new source discovered by the RXTE ASM and follow-up
observations with the RXTE PCA.
Observations with the RXTE All-Sky Monitor on 2006 Jan. 26 suggested
the sudden appearance of a very bright X-ray source near ra=274.56,
dec=-32.92 (degrees, J2000). The angular proximity to the sun
limited the number of dwells and the position accuracy. The (2-12 keV) flux was
0.93 (0.03) Crab, compared to an upper limit (3 sigma) of 0.05 mCrab
on Jan. 25. The spectrum appeared very soft, as frequently exhibited
by black hole candidates.
The RXTE PCA pointed at the ASM position Jan 27 at 21 UT and confirmed
the presence of a bright soft source. On Jan 28 at 14 UT the PCA
scanned over the position and determined a position of ra=274.425,
dec=-33.018, for which the systematic errors should be less than 30"
(Jahoda et al. 2006). The spectrum exhibits little absorption (< 10^
21 cm^-2). For both observations it can be described by black body
contributions at about 0.8 and 0.4 keV and a powerlaw with photon
index of 2-3. The fluxes were 1.2 and 1.35 Crab(2-10 keV),
respectively, and 15 and 22 mCrab (10-30 keV). Source rms variability
was only 1.3% during 900 seconds of observation.