TITLE:   GCN CIRCULAR
NUMBER:  16919
SUBJECT: GRB 141017A: Swift detection of a burst
DATE:    14/10/17 18:50:12 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

F. E. Marshall (NASA/GSFC), S. D. Barthelmy (GSFC),
S. B. Cenko (GSFC), M. M. Chester (PSU), J. R. Cummings (NASA/UMBC),
H. A. Krimm (CRESST/GSFC/USRA), A. Y. Lien (GSFC/UMBC),
V. Mangano (PSU), K. L. Page (U Leicester),
B. Sbarufatti (INAF-OAB/PSU), M. H. Siegel (PSU) and
E. Troja (NASA/GSFC/UMCP) report on behalf of the Swift Team:

At 18:25:28 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 141017A (trigger=615672).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 93.629, -58.554 which is 
   RA(J2000)  =  06h 14m 31s
   Dec(J2000) = -58d 33' 15"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows two main peaks
with a duration of about 60 sec.  The peak count rate
was ~6000 counts/sec (15-350 keV), at ~50 sec after the trigger. 

The XRT began observing the field at 18:26:52.0 UT, 84.0 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 93.6284, -58.5836 which is equivalent to:
   RA(J2000)  = +06h 14m 30.82s
   Dec(J2000) = -58d 35' 01.0"
with an uncertainty of 4.8 arcseconds (radius, 90% containment). This
location is 106 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 4.83e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 91 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
0.04. 

Burst Advocate for this burst is F. E. Marshall (marshall 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.)