GCN Circular 6121

A. Parsons (GSFC), L. Barbier (GSFC), S. D. Barthelmy (GSFC),
J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC),
H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), 
T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS), 
M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC)
on behalf of the Swift-BAT team:
  
Using the data set from T-240 to T+1000 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 070220
(trigger #261299)  (Stamatikos, et al., GCN Circ. 6114
Not found
 
 
).  The BAT 
ground-calculated position is RA, Dec = 34.800, 68.800 deg which is 
   RA(J2000) = 2h 19m 11.9s 
   Dec(J2000) = 68d 48' 1.6" 
with an uncertainty of 1 arcmin, (radius, sys+stat, 90% containment).  
The partial coding was 64%.

The mask-weighted lightcurve shows a multiple peaked structure.  
T90 (15-350 keV) is 129 +- 6 sec (estimated error including systematics).
 
The time-averaged spectrum from T-17 to T+240 is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is 1.45
+- 0.04. The fluence in the 15-150 keV band is 1.06 +- 0.02 x 10^-5 erg/cm2.
The 1-sec peak photon flux measured from T+12 sec in the 15-150 keV band is
5.88 +- 0.29 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.