GRB 050418***A***, Swift-BAT refined analysis
 
<somebody goes first>
<add the BA alphabetically>
S. D. Barthelmy (GSFC), 
W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC),
N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA),
A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC),
D. M. Palmer (LANL),
T. Sakamoto (AGU),
M. Stamatikos (OSU),
T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):
 
Using the data set from T-299 to T+303 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 050418***A*** (trigger #114893)
(NAME, et al., GCN Circ. xxxx).  The BAT ground-calculated position is
RA, Dec = 44.338, -18.542 deg which is 
   RA(J2000)  =  02h 57m 21.1s 
   Dec(J2000) = -18d 32' 30.3" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 35%.
 
[Description about the mask-weighted light curve]
T90 (15-350 keV) is 81.8 +- 1.4 sec (estimated error including systematics).
 
The time-averaged spectrum from T-8.4 to T+80.6 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 1.28 +- 0.25, 
and Epeak of 98.2 +- 48.6 keV (chi squared 49.64 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 5.1 +- 0.2 x 10^-06 erg/cm2
and the 1-sec peak flux measured from T+0.72 sec in the 15-150 keV band is
3.7 +- 0.3 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.67 +- 0.06 (chi squared 56.95 for 57 d.o.f.).  All the quoted errors
are at the 90% confidence level. 
 
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/114893/BA/