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Swift/XRT localization of IGR J17361-4441 in the globular cluster NGC 6388

ATel #3566; C. Ferrigno, E. Bozzo, L. Gibaud (ISDC, Switzerland) J. Rodriguez (CEA, France)
on 17 Aug 2011; 12:52 UT
Credential Certification: Carlo Ferrigno (Carlo.Ferrigno@unige.ch)

Subjects: Globular Cluster, Transient

Referred to by ATel #: 3595, 3617, 3627, 3958

A Swift/XRT follow-up observation of IGR J17361-4441 (ATEL #3565) has been carried out in photon counting mode on 2011-08-16 from 16:59 to 19:03 UT (exposure time 1.9 ks), to refine the transient position

We propose an astrometrically-corrected X-ray position of: RA, Dec = (264.0729, -44.7353) which is equivalent to:
RA (J2000): 17 36 17.5
Dec (J2000): -44 44 07.1
The 90% c.l. confinement radius is 2.1 arcsec. (We have used the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue, see http://www.swift.ac.uk/user_objects and Evans et al. 2009, MNRAS, 397, 1177). These coordinates locate IGR J17361-4441 within the Globular Cluster NGC 6388.

The average spectrum can be fitted by an absorbed power-law of index 0.7±0.2 and NH<2.6×1021 cm-2. The 0.5-10 keV absorbed flux is 4.2+0.6-1.4×10-11 erg/s/cm2 (uncertainties at 90% c.l.). The harder photon index with respect to the hard X-ray suggests the presence of a turn-over in the spectrum, typical of low mass X-ray binaries and accreting binaries in general.

We thanks the Swift team for the rapid scheduling of this follow-up observation and encourage follow-up observations at all wavelengths to unveil the nature of this transient.