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Swift/XRT detection and localization of IGR J01583+6713

ATel #673; J. A. Kennea, J. L. Racusin, D. N. Burrows, S. Hunsberger, J. A. Nousek (PSU) and N. Gehrels (NASA/GSFC)
on 13 Dec 2005; 12:21 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Jamie A. Kennea (kennea@astro.psu.edu)

Subjects: X-ray, Transient

Referred to by ATel #: 681

At 00:00 UT on December 13th, 2005 Swift began a Target of Opportunity observation of IGR J01538+6713, a recently discovered hard X-ray transient source discovered by INTEGRAL (Steiner et al., ATEL #672). Analysis of 5ks of XRT data from this observation reveals a single point source inside the INTEGRAL 2 arcminute radius error circle at the following coordinates:

RA = 01:58:18.2, Dec = +67:13:25.9 (J2000),

with an estimated uncertainty of 3.5 arcseconds (90% containment). This location is 17 arcseconds from the INTEGRAL position reported in ATEL #672, and is not consistent with the position of any catalogued X-ray source. A J=11.5 2MASS catalogue object is 2.9 arcseconds from the XRT position. This object is also present in the USNO catalogue, with reported magnitudes of R=13.9 and B=15.3. We encourage optical follow-up of this location to determine if this source in the optical counterpart of IGR J01538+6713.

Spectral fitting of this source is uncertain, due to low source flux. However an absorbed power-law model shows that IGRJ01583+6713 is highly absorbed, with N_H approximately 10^23 cm^-2. This absorption is in excess of the estimated galactic value of N_H is 4.7 x 10^21 cm^-1. The measured flux is approximately 1.5 x 10^-11 erg/s/cm^-2 (0.2-10 keV), uncorrected for absorption. IGR J01583+6713 does not appear to be fading during our observation.