TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3597
SUBJECT: GRB 050713A :  Swift-BAT Refined Analysis
DATE:    05/07/13 18:04:21 GMT
FROM:    David Palmer at LANL  <palmer@nis.lanl.gov>

D. Palmer (LANL), S. Barthelmy, L. Barbier (GSFC),
J. Cummings (GSFC/NRC), E. Fenimore (LANL), N. Gehrels (GSFC),
D. Hullinger (GSFC/UMD), H. Krimm (GSFC/USRA),
C. Markwardt (NASA GSFC/UMD), J. Nousek (PSU), A. Parsons (GSFC),
T. Sakamoto (GSFC/NRC), G. Sato (ISAS), M. Suzuki (Saitama),
M. Tripicco (GSFC/SSAI), J. Tueller (GSFC)
on behalf of the Swift-BAT team:

Using the full data set from the recent telemetry downlink, further
analysis of Swift-BAT GRB 050713A (Trigger #145675; Falcone et al., GCN
Circ 3581) yields a refined position of RA, Dec 320.587, +77.070 {21h
22m 21s, +77d 04' 12"} (J2000) with an uncertainty of 3 arcmin
(radius, 90% confidence, statistical+systematic).

The burst duration (T90) was determined to be 70 +/- 10 seconds (15-350
keV) starting at T-1.0 seconds.  There is an initial ~12 second long basically
square hump which shows some structure:  three separate peaks of roughly
equal intensity in the 15-50 keV energy band, but falling in intensity with time
above 100 keV.  There are additional, much smaller peaks at T-60, T+50
T+65, and T+105 seconds.

The spectrum over the interval from T-70 to T+121 seconds can be fit
with a power law with photon index 1.58 +/- 0.07 and yields a fluence of
9.1 +/- 0.6 X 10^-6 erg/cm^2 in the 15-350 keV band.  The peak flux
in a 1-sec wide window starting at T+1.2 seconds is 6.0 +/- 0.4 ph/cm^2/sec.