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INTEGRAL observations of XTEJ1752-223

ATEL # 2530; Manousakis A., Ferrigno C. (ISDC-University of Geneva), Weidenspointner G. (MPE), Kuulkers E. (ESA/ESAC) Bozzo E. (ISDC-University of Geneva), Mereghetti S. (IASF-Mi/INAF), Gotz D. (CEA), Fiocchi M. (IASF-Rm/INAF), Watanabe K. (FGCU) Rothschild R. (UCSD), Kuiper L.M. (SRON), Chenevez J. (DTU Space), Caballero I. (CEA), Ducci L. (IASF-Mi/INAF) Bird A.J. (Southampton, UK), Puehlhofer G. (IAA Tuebingen), Sanchez C. (ESA/ESAC), Del Santo M (IASF-Rm/INAF) Negueruela I. (Alicante), Bianchin V. (IASF-Bo/INAF), Prat L. (CEA), Paizis A. (IASF-Mi/INAF), Tarana A. (IASF-Rm/INAF), Panessa F. (IASF-Rm/INAF), Fiamma C. (IASF-Rm/INAF), Kreykenbohm I. (Dr. Karl Remeis Sternwarte Bamberg)) Terrier R. (APC)
on 1 Apr 2010; 11:34 UT
Distributed as an Instant Email Notice (Transients)
Password Certification: Nami Mowlavi (Nami.Mowlavi@obs.unige.ch)

Subjects: Binaries, Black Holes, Transients

The latest RXTE observations of XTEJ1752-223 detected this source
in an intermediate state, and suggested that a spectral transition
from the soft to the hard state was most likely taking place
(Atel #2518).

Following this announcement, we analyzed the INTEGRAL data
of the latest revolutions in the direction of the source.

In the period preceding the suspected spectral change,
XTEJ1752-223 was inside the IBIS/ISGRI field of view
from 2010-03-25 13:17 to 2010-03-27 02:08 (UTC).
The source was detected at 6 sigma level in the 20-40 keV ISGRI mosaic
(effective exposure time 21 ks), and the corresponding X-ray flux was
of 7E-11 erg/cm^2/s. The ISGRI spectrum could be only poorly characterized
and was compatible with a power-law of photon index 3+/-1.

XTEJ1752-223 was again in the FOV of ISGRI after the announced
spectral transition from 2010-03-27 at 10:03 to 2010-03-30 at 02:08 (UTC).
The source was detected at 21 sigma in the 20-40 keV ISGRI mosaic, and
the corresponding X-ray flux was 2.8E-10 erg/cm^2/s (effective exposure time 36 ks).
The ISGRI spectrum could be described by a power law with a
photon index of 2.8+/-0.3 above 23 keV.

Further observations of the source took place from 2010-03-30 09:52
to 2010-03-30 13:33 (UTC). The source was detected at 15 sigma in
the 20-40 keV ISGRI mosaic (effective exposure time 7.3 ks), and the
corresponding X-ray flux was 3.2E-10 erg/cm^2/s.
The ISGRI spectrum above 25 keV could be roughly modeled
with a power-law of photon index 1.7+/-0.5.

The measured change in the spectral photon index of
XTEJ1752-223 supports the idea that this source is
presently undergoing a spectral state transition.

XTEJ1752-223 was outside the JEMX2 FOV for the
entire observational period.


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R. E. Rutledge , Editor
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