TITLE: GCN CIRCULAR NUMBER: 13090 SUBJECT: GRB 120324A: Swift detection of a burst DATE: 12/03/24 06:14:22 GMT FROM: David Palmer at LANL B.-B. Zhang (PSU), A. P. Beardmore (U Leicester), D. Grupe (PSU), C. Guidorzi (U Ferrara), E. A. Hoversten (PSU), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the Swift Team: At 05:59:11 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 120324A (trigger=518507). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 291.084, +24.145 which is RA(J2000) = 19h 24m 20s Dec(J2000) = +24d 08' 43" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 90 sec. The peak count rate was ~10500 counts/sec (15-350 keV), at ~34 sec after the trigger. The XRT began observing the field at 06:00:26.4 UT, 75.1 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 291.0771, 24.1290 which is equivalent to: RA(J2000) = +19h 24m 18.50s Dec(J2000) = +24d 07' 44.4" with an uncertainty of 4.7 arcseconds (radius, 90% containment). This location is 61 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 1.92e-08 erg cm^-2 s^-1 (0.2-10 keV). No UVOT data are available at this time. Burst Advocate for this burst is B.-B. Zhang (bbzhang AT 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.)