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Swift/XRT observations of XTE J1727-476/IGR J17269-4737

ATel #626; J. A. Kennea (PSU), D. Palmer (LANL), D. Burrows (PSU), N. Gehrels (GSFC)
on 12 Oct 2005; 17:58 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 #: 628, 629, 631, 632

On October 12th at 00:50 UT Swift began a 1.1ks observation of the field centered on the position reported for XTE J1727-476 in ATEL #623 (Levine et al). The field of view also contained the position reported for IGR J17269-4737 in ATEL #624 (Turler et al). We find a single bright, uncatalogued point source at the following coordinates: RA(J2000): 17:26:49.8, Dec(J2000): -47:38:23.2, with an uncertainty of 8 arcseconds radius (90% containment). This position lies 6.5 arcminutes from the XTE position quoted in ATEL #623, and 1.2 arcminutes from the INTEGRAL position quoted in ATEL #624, inside the INTEGRAL error circle for IGR J17269-4737. Although this source is outside of the quoted XTE error circle, no source lies within the XTE error circle. We therefore conclude that the Swift detected point source is IGR J17269-4737 and that this source is the same as XTE J1727-476.

Spectral fits to this source reveal that the source is not well fit by a single power-law fit (Reduced Chi^2 = 2.25 for 319 dof). A Thermal Bremsstrahlung model gives a better fit (reduced chi^2 = 1.63 for 319 dof), with N_H = 3.1 +/- 0.1 x 10^21 cm^-2 and kT = 1.58 +/- 0.03 keV. The level of absorption is in agreement with the expected galactic absorption in this direction. The 0.2-10 keV flux is 1.75 x 10^-9 erg/s/cm^2, 3.75 x 10^-9 erg/s/cm^2 corrected for absorption. Assuming a distance of 8.5 kpc to this source, this converts to a X-ray luminosity of 3.8 x 10^38 erg/s (0.2-10 keV).

The source was outside of the UVOT field of view, so no optical data is currently available.