IGR J18175-1530: a new hard X-ray transient detected by INTEGRAL
ATel #1248; A. Paizis (INAF-IASF Milano), V. Beckmann (ISDC), D. Gotz (CEA Saclay), L. Sidoli, A. Bazzano, G. Belanger, M. Cadolle-Bel, J. Chenevez, A. De Rosa, E. Kuulkers, M. Falanga, M. Fiocchi, L. Kuiper, J. C. Leyder, S. Mereghetti, S. Piraino, K. Pottschmidt, S. Shaw, J. Tomsick, K. Watanabe, R. Walter, G. Weidenspointner
on 25 Oct 2007; 14:05 UT
Credential Certification: Adamantia Paizis (firstname.lastname@example.org)
Subjects: Radio, X-ray, AGN, Binary, Black Hole, Cataclysmic Variable, Neutron Star, Transient, Pulsar
During the INTEGRAL Key Programme observations of the Galactic Centre
(revolutions 599, 600 and 601, from 2007-09-09 to 2007-09-17),
the IBIS/ISGRI telescope detected a new hard X-ray transient,
IGR J18175-1530, at the position RA = 18 17 34.3, DEC= -15 30 41
(statistical error of 2.5').
The source is detected in the combined data set at 10 sigma in the 20-40
keV band with a rate of 1.5+-0.1 cps (about 9 mCrab) for an effective exposure
time of 307 ksec, using OSA7 analysis software.
IGR J18175-1530 is detected (6-7 sigma) also in the single revolution
sky maps but it is neither detected at a single pointing level (2ksec),
nor in the IBIS/ISGRI mosaic images in the 40-100 keV band. IGRJ18175-1530
has been in the IBIS/ISGRI field of view also prior to our detection,
in August 2007 (revolutions 594, 595, 596) but was not detected.
Unfortunately, IGR J18175-1530 was always too far off-axis (> 9 degrees)
to be covered by JEM-X.
An XMM-Newton observation of the source position performed on 2003-04-10 did not detect
the object. We derive a 3-sigma upper limit of 3.3E-02 cps (0.3-12 keV, EPIC
pn) at the source position. Using PIMMS and assuming a Crab-like spectrum
with a 1e22cm-2 column density (the total Galactic in the source
direction), we derive upper limits of 4e-13 ergs/cm/cm/s and 7e-13
ergs/cm/cm/s for the observed and unabsorbed source flux, respectively.
This implies an upper limit to the luminosity of about 1e34 erg/s at 10 kpc.
It is interesting to note that the radio source GPSR5 15.308+0.226 (RA =
274.41058, DEC = -15.52519, Becker et al. 1994) is 1.3' away from IGR
J18175-1530, well within the IBIS/ISGRI location error (2.5').
INTEGRAL will not be monitoring this region in the next months,
follow-up observations are encouraged.