TITLE:   GCN CIRCULAR
NUMBER:  20087
SUBJECT: GRB 161022A: Swift detection of a burst
DATE:    16/10/22 03:03:37 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

M. Stamatikos (OSU/NASA/GSFC), S. D. Barthelmy (GSFC),
J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC),
K. L. Page (U Leicester), D. M. Palmer (LANL) and T. N. Ukwatta (LANL)
report on behalf of the Swift Team:

At 02:43:40 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 161022A (trigger=718655).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 128.967, +54.365 which is 
   RA(J2000)  =  08h 35m 52s
   Dec(J2000) = +54d 21' 54"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a single peak
with a duration of about 20 sec.  The peak count rate
was ~1200 counts/sec (15-350 keV), at ~2 sec after the trigger. 

The XRT began observing the field at 02:45:53.4 UT, 133.3 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 129.00074, 54.34876 which is equivalent
to:
   RA(J2000)  = 08h 36m 00.18s
   Dec(J2000) = +54d 20' 55.5"
with an uncertainty of 3.5 arcseconds (radius, 90% containment). This
location is 91 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 http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (4.13 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 1.2
(+1.30/-1.19) x 10^21 cm^-2 (90% confidence). 

No UVOT data are available at this time. 

Burst Advocate for this burst is M. Stamatikos (Michael.Stamatikos-1 AT 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.)