TITLE: GCN CIRCULAR NUMBER: 9615 SUBJECT: GRB 090705: Swift detection of a possible burst DATE: 09/07/05 05:36:54 GMT FROM: Scott Barthelmy at NASA/GSFC T. N. Ukwatta (GSFC/GWU), S. D. Barthelmy (GSFC), V. D'Elia (ASDC), E. A. Hoversten (PSU), J. A. Kennea (PSU), C. B. Markwardt (CRESST/GSFC/UMD), C. Pagani (PSU), D. M. Palmer (LANL), M. Perri (ASDC), T. Sakamoto (NASA/UMBC), M. H. Siegel (PSU), M. A. Stark (PSU) and G. Stratta (ASDC) report on behalf of the Swift Team: At 05:11:31 UT, the Swift Burst Alert Telescope (BAT) triggered and located possible GRB 090705 (trigger=356516). Swift slewed almost immediately to the location. The BAT on-board calculated location is RA, Dec 318.484, +62.578 which is RA(J2000) = 21h 13m 56s Dec(J2000) = +62d 34' 42" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is usual for an image trigger, there is no obvious variation in the immediately available light curve. The XRT began observing the field at 05:17:25.8 UT, 354.7 seconds after the BAT trigger. No source was detected in the promptly available XRT data. We are waiting for the full dataset to detect and localise the XRT counterpart. UVOT took a finding chart exposure of 150 seconds with the White filter starting 357 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 25% of the BAT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the BAT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.83. Due to the marginal detection (7.02 sigma) in the BAT image, and the non-detection by XRT, we cannot confirm that this is a real burst. Further analysis will require the full downlink of data through the Malindi ground station. Burst Advocate for this burst is T. N. Ukwatta (tilan.ukwatta AT gmail.com). 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.)