GCN Circular 3284

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

At 22:35:54.1 UT Swift-BAT detected GRB 050416b (trigger=114797)
(GCN Circ 3279, Hullinger et al.).  The refined BAT ground position
is (RA,Dec) = 133.854,  11.182, [deg; J2000] +- 3 arcmin, (95%
containment).  The partial coding fraction was 16%. 
 
The moon is moving towards the position of the GRB, and Swift will not 
be able to observe for several days because of the spacecraft moon 
angle constraint. 

The BAT mask weighted light curve shows a FRED-like structure.   
T90 (15-350 keV) is (5.4 +- 0.9) seconds (estimated error including 
systematics).

The time-averaged spectrum is well fitted in a simple power-law 
model.  The photon index is 1.5 +- 0.2.  The fluence in the 15-350 
keV band is (2.1 +- 0.3) x 10^-6 erg/cm2.   The peak photon flux in 
the 15-350 band is (7.9 +- 0.7) ph/cm2/s.  The quoted errors are at 
the 90% confidence level.