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Swift detection of outburst from the SFXT IGR J18410-0535

ATel #2661; M. De Pasquale (UCL-MSSL), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU), S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU), V. Mangano (INAF-IASFPA), D. M. Palmer (LANL), P. Romano (INAF-IASFPA), B. Sbarufatti (INAF-OAB/IASFPA), R. L. C. Starling (U Leicester) and L. Vetere (PSU) report on behalf of the Swift Team
on 5 Jun 2010; 19:29 UT
Distributed as an Instant Email Notice Request For Observations
Credential Certification: Pat Romano (romano@ifc.inaf.it)

Subjects: X-ray, Gamma Ray, Request for Observations, Binary, Transient, Pulsar

Referred to by ATel #: 2662, 3018

At 17:23:30 UT, the Swift Burst Alert Telescope (BAT) detected increased flux from the Supergiant Fast X-Ray Transient IGR J18410-0535. Swift slewed to the source immediately after its detection. The BAT on-board calculated location is RA, Dec 280.267, -5.615 which is
RA(J2000) = 18h 41m 04s
Dec(J2000) = -05d 36' 53"
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty), consistent with the known source location. As is typical for long image detections, the immediately available light curve shows no obvious activity.

The XRT began observing the field at 17:51:50.5 UT, 1700 seconds after the BAT trigger. Using promptly downlinked data we find an X-ray source located at RA, Dec 280.25128, -5.59666 which is equivalent to:
RA(J2000) = 18h 41m 0.40s
Dec(J2000) = -05d 35' 46.5"
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This is consistent with the identification of this source as IGR J18410-0535. The position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper.

A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 1.59e+22 cm^-2 (Kalberla et al. 2005).

UVOT took a finding chart exposure of 150 seconds with the White filter starting 1705 seconds after the BAT trigger. No credible optical transient has been found in the initial data products. No correction has been made for the large, but uncertain extinction expected.