XTE J1746-322 = IGR J17464-3213 = H1743-322
ATel #133; C. B. Markwardt (U. Maryland & GSFC) and J. H. Swank (GSFC)
on 29 Mar 2003; 03:15 UT
Credential Certification: Craig B. Markwardt (craigm@lheamail.gsfc.nasa.gov)
Subjects: X-ray, Gamma Ray, Binary, Black Hole, Transient
C. B. Markwardt (U. Maryland & GSFC) and J. H. Swank (GSFC) report the
detection of a new source in RXTE PCA galactic bulge scans on MJD
52723.84, designated XTE J1746-322. The best fit position is R.A. =
17h46m30s, Decl. = -32o10' (equinox 2000.0), with approximate errors
of 10', due to nearby confusing sources. This position is consistent
with that of the newly reported INTEGRAL source IGR J17464-3213 (ATEL
#132).
A pointed RXTE observation occurred on MJD 52726.83 with total good
exposure time of 3.4 ks. The mean fluxes in the 2-10, 15-40, and
40-100 keV bands were approximately 50, 200 and 220 mCrab
respectively. Compared to the reported INTEGRAL fluxes, the intensity
appears to have increased. A strong quasiperiodic oscillation with
period ~20 sec, and r.m.s. amplitude ~25%, is clearly seen in the
X-ray light curve. No coherent pulsations were detected.
The X-ray spectrum is consistent with an absorbed power law with
photon index 1.49 +/- 0.01 and an absorption column of 2.4 x 10**22
cm**-2. Signatures of compton reflection are apparent in the
continuum spectrum, but there is no evidence for a line at 6.4 keV,
with upper limit on the equivalent width of 45 eV (90 % confidence).
The INTEGRAL source position is consistent, to within the cited 2'
error bar, with the HEAO source H1743-322 (also known as H1741-322).
The spectrum and timing properties suggest that it is indeed a black
hole candidate.
