GCN Circular 11818

Subject

GRB 110319B BAT refined analysis

Event

Date

2011-03-22T15:38:58Z (16 years ago)

From

Jay R. Cummings at NASA/GSFC/Swift <james.r.cummings@nasa.gov>

D. M. Palmer (LANL), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
C. B. Markwardt (GSFC), A. Melandri (INAF-OAB), T. Sakamoto (GSFC/UMBC),
M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):

Using the data set from T-48 to T+52 sec, we report further analysis of
GRB 110319B (Cummings, et al., GCN Circ. 11813Loading...
 
 ).  The refined BAT position
is RA, Dec =  326.088, -56.774 deg, which is
    RA(J2000)  =  21h 44m 21.1s
    Dec(J2000) =  -56d 46m 26s
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
This position is 33 arcsec from the XRT position of the candidate
afterglow.  The partial coding was 100%.

The mask-weighted light curve shows a single FRED peak starting at ~T-3 sec,
peaking at ~T0, and ending at ~T+20 sec.  T90 (15-350 keV) is 14.5 +- 2 sec
(estimated error including systematics).

The time-averaged spectrum from T-3.5 to T+16.5 sec is best fit by a simple
power law.  This fit gives a photon index 1.39 +- 0.05.  For this
model the total fluence in the 15-150 keV band is 1.0 +- 0.1 x 10-6  erg/cm2
and the 1-sec peak flux measured from T0 sec in the 15-150 keV band is
1.25 +- 0.15 ph/cm2/sec.