GCN Circular 23845

A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC),
P. D'Avanzo (INAF-OAB), J. A. Kennea (PSU), N. J. Klingler (PSU),
M. H. Siegel (PSU) and A. Tohuvavohu (PSU) report on behalf of the
Neil Gehrels Swift Observatory Team:

At 15:44:08 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 190203A (trigger=887512).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 22.577, +55.738 which is 
  RA(J2000) = 01h 30m 18s
  Dec(J2000) = +55d 44' 18"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multi-peaked
structure with a duration of about 55 sec.  The peak count rate
was ~2000 counts/sec (15-350 keV), at ~2 sec after the trigger. 

The XRT began observing the field at 15:46:04.0 UT, 115.7 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 22.5984, 55.7211 which is equivalent to:
   RA(J2000)  = 01h 30m 23.62s
   Dec(J2000) = +55d 43' 16.0"
with an uncertainty of 4.8 arcseconds (radius, 90% containment). This
location is 74 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 4.46e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 120 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  =	01:30:23.19 =  22.59662
  DEC(J2000) = +55:43:20.7  =  55.72241
with a 90%-confidence error radius of about 0.63 arc sec. This position is 5.9
arc sec. from the center of the XRT error circle. The estimated magnitude is
18.58 with a 1-sigma error of about  0.15. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.64. 

Burst Advocate for this burst is A. Y. Lien (amy.y.lien 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: /too.html.)