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XTE J1752-223: RXTE PCA Observation shows black hole candidate

ATel #2269; N. Shaposhnikov (U. Maryland & NASA/GSFC), C. B. Markwardt (U. Maryland & NASA/GSFC), J. H. Swank (NASA/GSFC)
on 27 Oct 2009; 19:58 UT
Distributed as an Instant Email Notice Request For Observations
Credential Certification: Jean Swank (swank@milkyway.gsfc.nasa.gov)

Subjects: X-ray, Request for Observations, Binary, Black Hole, Transient

Referred to by ATel #: 2278, 2280, 2391, 2424, 2549

On 2009-10-26 at 15:03 UT, the RXTE PCA made its first pointed observation of the newly discovered transient source XTE J1752-223 (ATels #2258, #2259, #2261, #2263, #2265, #2268). The PCA spectrum is consistent with the source being in the black hole low-hard state dominated by a power law component with photon index 1.38 +/- 0.01 with a weak black body with kT=0.83+/-0.01 keV. A prominent iron line is also seen at ~6.4 keV, with equivalent width of 95 eV. The fluxes in the 2-10 and 10-50 keV energy ranges were 2.7x10{-09} and 7.2x10^{-09} ergs cm^{-2} s^{-1} respectively. The Fourier power spectrum shows band-limited noise with a break at 0.08 Hz and total variability of about 30 per cent. Overall spectral and timing properties are strongly reminiscent of the extreme low-hard states exhibited by Cyg X-1 and GX 339-4.

The RXTE monitoring will continue on a daily basis, as a transition to the soft state is highly probable.