TITLE:   GCN CIRCULAR
NUMBER:  20462
SUBJECT: GRB 170115A: Swift detection of a burst
DATE:    17/01/15 21:15:39 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

K. L. Page (U Leicester), S. D. Barthelmy (GSFC), D. N. Burrows (PSU),
A. Cholden-Brown (PSU), C. Gronwall (PSU), J. A. Kennea (PSU),
H. A. Krimm (CRESST/NSF/USRA), F. E. Marshall (NASA/GSFC) and
D. M. Palmer (LANL) report on behalf of the Swift Team:

At 20:50:08 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170115A (trigger=733103).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 332.154, +13.781 which is 
   RA(J2000) = 22h 08m 37s
   Dec(J2000) = +13d 46' 51"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve is only immediately
available until T+8 seconds due to a telemetry gap, showing a
rise to a maximum rate of ~800 counts/s at the end of that period. 

The XRT began observing the field at 20:51:39.5 UT, 91.5 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 332.1390, 13.7283 which is equivalent to:
   RA(J2000)  = +22h 08m 33.36s
   Dec(J2000) = +13d 43' 41.9"
with an uncertainty of 6.3 arcseconds (radius, 90% containment). This
location is 196 arcseconds from the BAT onboard position, outside 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 5.14e-10 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 99 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
0.07. 

Burst Advocate for this burst is K. L. Page (klp5 AT leicester.ac.uk). 
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.)