TITLE: GCN CIRCULAR NUMBER: 43387 SUBJECT: Swift Trigger 1439093: is probably not GRB 260113A DATE: 26/01/13 10:47:55 GMT FROM: K.L. Page at U Leicester <klp5@leicester.ac.uk> R. Gupta (NASA GSFC), A. Y. Lien (U Tampa), K. L. Page (U Leicester), D. M. Palmer (LANL), C. Salvaggio (INAF-OAB) and B. Sbarufatti (INAF-OAB) report on behalf of the Neil Gehrels Swift Observatory Team: At 10:14:06 UT, the Swift Burst Alert Telescope (BAT) triggered and located an event (trigger=1439093). Swift slewed immediately to the location. The BAT on-board calculated location is RA, Dec 357.372, +9.041 which is RA(J2000) = 23h 49m 29s Dec(J2000) = +09d 02' 29" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). We only have limited BAT light curve information at this moment, current light curve showed some potential pulse-like structure in the low energy band (15-25 keV), but nothing significant in other energy bands. Therefore, the pulse-like structure may be due to noisy detectors. Further ground analysis is required to determine the nature of this trigger. The XRT began observing the field at 10:16:22.6 UT, 136.1 seconds after the BAT trigger. No source was detected in 1.5 ks of promptly downlinked data. UVOT took a finding chart exposure of 150 seconds with the White filter starting 139 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 0.098. Due to the marginal detection of this event in the BAT Image (6.5 sigma) and the lack of the an XRT counterpart detection, we believe that this trigger is most likely to be a statistical fluctuation in the instrument and not a true astrophysical event. Determination of the reality of this event will require the full downlinked dataset. We retain the name GRB 260113A for this event to avoid confusion. Burst Advocate for this burst is R. Gupta (rahulbhu.c157 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/) View this GCN Circular online at https://gcn.nasa.gov/circulars/43387. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...