TITLE: GCN CIRCULAR NUMBER: 8034 SUBJECT: Swift detection of XTE J1701-407 DATE: 08/07/27 22:48:15 GMT FROM: Scott Barthelmy at NASA/GSFC T. Sakamoto (NASA/UMBC), S. D. Barthelmy (GSFC), A. P. Beardmore (U Leicester), M. M. Chester (PSU), N. Gehrels (NASA/GSFC), S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU), S. D. Hunsberger (PSU), J. A. Kennea (PSU), C. B. Markwardt (CRESST/GSFC/UMD), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL), A. M. Parsons (GSFC), D. Perez (U Leicester), R. L. C. Starling (U Leicester) and T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team: At 22:31:19 UT, the Swift Burst Alert Telescope (BAT) triggered and located XTE J1701-407 (trigger=318166). Swift slewed immediately to the transient. The BAT on-board calculated location is RA, Dec 255.478, -40.841 which is RA(J2000) = 17h 01m 55s Dec(J2000) = -40d 50' 26" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single peak with a duration of about 5 sec. The peak count rate was ~600 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 22:33:08.5 UT, 108.7 seconds after the BAT trigger. XRT found a bright X-ray source located at RA, Dec 255.4353, -40.8564 which is equivalent to: RA(J2000) = 17h 01m 44.4s Dec(J2000) = -40d 51' 23.0" with an uncertainty of 5.4 arcseconds (radius, 90% containment). This location is 128 arcseconds from the BAT onboard position, within the BAT error circle. This is 7.2 arcseconds from the previously determined UVOT-enhanced XRT position given in Starling and Evans, Atel 1621. No event data are yet available to determine the column density using X-ray spectroscopy. UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm) filter starting 120 seconds after the BAT trigger. No optical transient has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The 3-sigma upper limit at the position of the XRT source is 19.3 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the large, but uncertain extinction expected. Burst Advocate for this burst is T. Sakamoto (Taka.Sakamoto AT nasa.gov). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.)