TITLE: GCN CIRCULAR NUMBER: 15505 SUBJECT: GRB 131120A: Swift detection of a burst DATE: 13/11/20 14:47:45 GMT FROM: David Palmer at LANL A. Maselli (INAF-IASFPA), S. T. Holland (STScI), J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL), T. Sakamoto (AGU), B. Sbarufatti (INAF-OAB/PSU) and M. H. Siegel (PSU) report on behalf of the Swift Team: At 14:37:56 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 131120A (trigger=578227). Swift could not slew to the burst due to a Sun constraint. The BAT on-board calculated location is RA, Dec 278.921, -11.997 which is RA(J2000) = 18h 35m 41s Dec(J2000) = -11d 59' 49" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is usual for image triggers, the immediately-available BAT lightcurve does not show strong variation. Due to a Sun observing constraint, Swift cannot slew to the BAT position until 15:39 UT on 2014 February 13. There will thus be no XRT or UVOT data for this trigger before this time. Burst Advocate for this burst is A. Maselli (maselli AT ifc.inaf.it). 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.)