GCN Circular 31468

A. Melandri (INAF-OAB), M. G. Bernardini (INAF-OAB), J.D. Gropp (PSU),
N. J. Klingler (GSFC/UMBC/CRESSTII), A. Y. Lien (U Tampa),
F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL),
T. M. Parsotan (GSFC/UMBC/CRESSTII), T. Sbarrato (INAF-OAB) and
M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 20:05:28 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 220117B (trigger=1093611).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 191.947, -28.744 which is 
   RA(J2000) = 12h 47m 47s
   Dec(J2000) = -28d 44' 38"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of about 20 sec.  The peak count rate
was ~1000 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 20:07:04.0 UT, 95.9 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 191.9514, -28.7446 which is equivalent to:
   RA(J2000)  = 12h 47m 48.34s
   Dec(J2000) = -28d 44' 40.6"
with an uncertainty of 6.5 arcseconds (radius, 90% containment). This
location is 14 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 4.69e-10 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of nominal 150.000 seconds with the White
filter starting 104 seconds after the BAT trigger. No credible afterglow
candidate has been found in the initial data products. Data from the 2.7'x2.7'
sub-image are not available at this time. 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 0.075. 

Burst Advocate for this burst is A. Melandri (andrea.melandri AT brera.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/)