TITLE: GCN CIRCULAR NUMBER: 12632 SUBJECT: GRB 111209A: Swift detection of a long burst with an optical counterpart DATE: 11/12/09 07:42:40 GMT FROM: David Palmer at LANL E. A. Hoversten (PSU), P. A. Evans (U Leicester), C. Guidorzi (U Ferrara), A. Y. Lien (NASA/GSFC/ORAU), C. Pagani (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/PSU), M. H. Siegel (PSU), M. C. Stroh (PSU), G. Tagliaferri (INAF-OAB) and B.-B. Zhang (PSU) report on behalf of the Swift Team: At 07:12:08 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 111209A (trigger=509336). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 14.360, -46.788 which is RA(J2000) = 00h 57m 26s Dec(J2000) = -46d 47' 17" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). After the original 320 second long image trigger, the source caused a second trigger (#509337) over the 64 second time interval starting at T+424s, at much higher intensity. The XRT began observing the field at 07:19:07.2 UT, 418.9 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 14.3462, -46.8005 which is equivalent to: RA(J2000) = 00h 57m 23.08s Dec(J2000) = -46d 48' 01.7" with an uncertainty of 4.7 arcseconds (radius, 90% containment). This location is 56 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy. The initial flux in the 2.5 s image was 1.20e-08 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 427 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at approximately the same position as the XRT source with a magnitude of 18.1. No correction has been made for the expected extinction corresponding to E(B-V) of 0.02. Burst Advocate for this burst is E. A. Hoversten (hoversten 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.)