TITLE: GCN CIRCULAR NUMBER: 16202 SUBJECT: GRB 140502A: Swift detection of a burst DATE: 14/05/02 08:44:00 GMT FROM: Scott Barthelmy at NASA/GSFC C. A. Swenson (PSU), S. D. Barthelmy (GSFC), M. M. Chester (PSU) and P. A. Evans (U Leicester) report on behalf of the Swift Team: At 08:30:20 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 140502A (trigger=597841). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 319.155, +49.018 which is RA(J2000) = 21h 16m 37s Dec(J2000) = +49d 01' 04" 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 25 sec. The peak count rate was ~2000 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 08:31:31.3 UT, 70.8 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 319.18744, 48.97012 which is equivalent to: RA(J2000) = 21h 16m 44.99s Dec(J2000) = +48d 58' 12.4" with an uncertainty of 4.0 arcseconds (radius, 90% containment). This location is 188 arcseconds from the BAT onboard position, outside the BAT error circle. This 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 9.47 x 10^21 cm^-2 (Willingale et al. 2013). UVOT took a finding chart exposure of 150 seconds with the White filter starting 74 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 none of the XRT error circle. 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 C. A. Swenson (cswenson AT astro.psu.edu). 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.)