TITLE:   GCN CIRCULAR
NUMBER:  3055
SUBJECT: GRB 050223 Swift/BAT detection of a burst
DATE:    05/02/23 05:54:42 GMT
FROM:    Jay R. Cummings at NASA/GSFC/Swift  <jayc@milkyway.gsfc.nasa.gov>

T. Mitani (ISAS), L. Barbier, S. Barthelmy, J. Cannizzo, J. Cummings (GSFC), 
M. Chester (PSU), E. Fenimore, M. Galassi (LANL), N. Gehrels (GSFC), 
D. Hullinger (GSFC/UMD), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), 
F. Marshall (GSFC), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC), 
G. Sato (ISAS), M. Suzuki (Saitama), T. Takahashi (ISAS), F. Tamburelli (ASDC), M. Tashiro (Saitama), J. Tueller (GSFC)


At 03:09:06 UT, the Swift Burst Alert Telescope (BAT) triggered and
located on-board GRB050223.  Because of the Earth-limb constraint,
the spacecraft could not immediately slew to the burst location.
The location became unconstrained at T+35 min, and the spacecraft slewed.
The XRT and UVOT instruments then began their standard set of pre-programmed
observing sequences.

Using the time interval of the burst, the ground-calculated location
is RA, Dec 271.390, -62.481 (J2000) with an uncertainty of 4 arcmin
(radius, including a systematic uncertainty, 90% containment).
The burst was 36 degrees off the BAT boresight (70% encoding).

The burst lightcurve has several small, short peaks on top of a slow rise 
and fall with a T90 duration of ~23 sec (and T50 is 10 sec). The 
peak flux is 0.8 ph/cm2/sec for a 1-sec interval (15-350 keV).  Using 
a simple power law model, the fluence is 7.4 e-7 erg/cm^2 (15-350 keV).