TITLE: GCN CIRCULAR NUMBER: 42147 SUBJECT: GRB 251007B: Swift detection of a burst DATE: 25/10/07 20:05:03 GMT FROM: David Palmer at LANL palmer@lanl.gov
A. Melandri (INAF-OAR), E. Ambrosi (INAF-IASFPA), A. D'Ai (INAF-IASFPA), V. D'Elia (SSDC & INAF-OAR), S. Dichiara (PSU), R. Gupta (NASA GSFC), N. J. Klingler (GSFC/UMBC/CRESSTII), N. P. M. Kuin (UCL-MSSL) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:
At 19:43:06 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 251007B (trigger=1402467). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 102.117, -10.303 which is RA(J2000) = 06h 48m 28s Dec(J2000) = -10d 18' 11" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). Due to the continued on-board processing of the previous burst (GRB 251007A) the BAT lightcurve is not immediately available.
The XRT began observing the field at 19:45:35.0 UT, 148.2 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 102.13232, -10.30328 which is equivalent to: RA(J2000) = 06h 48m 31.76s Dec(J2000) = -10d 18' 11.8" with an uncertainty of 3.7 arcseconds (radius, 90% containment). This location is 54 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 https://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 5.99 x 10^21 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 151 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image processing FAILED because of no aspect solution. Results from the list of sources generated on-board are not available at this time. No correction has been made for the expected extinction corresponding to E(B-V) of 0.785.
Burst Advocate for this burst is A. Melandri (andrea.melandri AT 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/)
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