TITLE:   GCN CIRCULAR
NUMBER:  22177
SUBJECT: GRB 171205A: Swift detection of a burst
DATE:    17/12/05 07:48:19 GMT
FROM:    Boris Sbarufatti at PSU  <bxs60@psu.edu>

V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), A. Y. Lien (GSFC/UMBC) and
B. Sbarufatti (PSU) report on behalf of the Swift Team:

At 07:20:43 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 171205A (trigger=794972).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 167.447, -12.604 which is 
   RA(J2000) = 11h 09m 47s
   Dec(J2000) = -12d 36' 12"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty). As is usual with an image trigger, the available
BAT light curve shows no significant structure. 

The XRT began observing the field at 07:23:08.5 UT, 144.7 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 167.4144, -12.5857 which is equivalent to:
   RA(J2000)  = +11h 09m 39.46s
   Dec(J2000) = -12d 35' 08.5"
with an uncertainty of 5.0 arcseconds (radius, 90% containment). This
location is 132 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. 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 153 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.05. 

Burst Advocate for this burst is V. D'Elia (delia AT asdc.asi.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.)