TITLE: GCN CIRCULAR NUMBER: 14361 SUBJECT: GRB 130408A: Swift detection of a burst DATE: 13/04/08 22:11:30 GMT FROM: David Palmer at LANL A. Y. Lien (NASA/GSFC/ORAU), W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU), N. Gehrels (NASA/GSFC), J. A. Kennea (PSU), D. Malesani (DARK/NBI), V. Mangano (INAF-IASFPA), C. Pagani (U Leicester), K. L. Page (U Leicester) and D. M. Palmer (LANL) report on behalf of the Swift Team: At 21:51:38 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 130408A (trigger=553132). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 134.401, -32.361 which is RA(J2000) = 08h 57m 36s Dec(J2000) = -32d 21' 37" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a double-peaked structure with a duration of about 12 sec. The peak count rate was ~3914 counts/sec (15-350 keV), at ~1 sec after the trigger. The XRT began observing the field at 21:54:08.6 UT, 149.9 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 134.40809, -32.36136 which is equivalent to: RA(J2000) = 08h 57m 37.94s Dec(J2000) = -32d 21' 40.9" with an uncertainty of 3.8 arcseconds (radius, 90% containment). This location is 21 arcseconds from the BAT onboard position, within 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. We cannot determine whether the source is fading at the present time. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 1.98 x 10^21 cm^-2 (Kalberla et al. 2005). UVOT data analysis is not available at this time. Burst Advocate for this burst is A. Y. Lien (yarleen 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.)