TITLE: GCN CIRCULAR NUMBER: 11484 SUBJECT: GRB 101224A: Swift detection of a short burst DATE: 10/12/24 05:56:50 GMT FROM: Hans Krimm at NASA-GSFC H. A. Krimm (CRESST/GSFC/USRA), W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester), M. M. Chester (PSU), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), J. M. Gelbord (PSU), S. T. Holland (CRESST/USRA/GSFC), V. Mangano (INAF-IASFPA), K. L. Page (U Leicester), J. L. Racusin (NASA/GSFC), A. Rowlinson (U Leicester), T. Sakamoto (NASA/UMBC) and M. H. Siegel (PSU) report on behalf of the Swift Team: At 05:27:13 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 101224A (trigger=440955). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 285.926, +45.715 which is RA(J2000) = 19h 03m 42s Dec(J2000) = +45d 42' 55" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single peak with a duration of about 0.5 sec and some possible later activity. The peak count rate was ~3000 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 05:28:31.4 UT, 77.7 seconds after the BAT trigger. No source was detected in the promptly available XRT data. We are waiting for the full dataset to detect and localise the XRT counterpart. UVOT took a finding chart exposure of 150 seconds with the White filter starting 83 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The overlap of the sub-image and the BAT error circle is uncertain. The overlap of the 8'x8' region for the list of sources generated on-board and the BAT error circle is uncertain. No correction has been made for extinction. This event is fairly near the galactic plane (galactic lon,lat = 76.11, +17.05 deg) so there is a possibility that it is a new galactic transient rather than a GRB. Further identification will await analysis of the full data set. We also note the presence of the galaxy pair MCG+08-34-033 6.5 arc minutes from the center of the BAT field of view. These galaxies are at a distance of z = 0.017832 ~75 Mpc Burst Advocate for this burst is H. A. Krimm (krimm AT milkyway.gsfc.nasa.gov). 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.)