TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  2906
SUBJECT: Swift-BAT Time History of GRB041219
DATE:    04/12/24 14:58:45 GMT
FROM:    Ed Fenimore at LANL  <efenimore@lanl.gov>

E. Fenimore (LANL), S. Barthelmy (GSFC), J. Cummings (GSFC), N. Gehrels
(GSFC), D. Hullinger (GSFC/UMD), H. Krimm (GSFC/USRA), C. Markwardt (UMD),
K. McLean (LANL), D. Palmer (LANL), A. Parsons (GSFC), J. Tueller (GSFC)  
on behalf of the Swift BAT team.

The INTEGRAL-Swift Burst of 041219 (GCN 2866, Gotz et al, GCN 2874,
Barthelmy et al.) had a time history that is rather rare: a precursor was
followed by 200 sec of mostly quiet emission before a huge spiky outburst
that lasted an additional 300 sec. This is one of the few events for which
there have been simultaneous ground observations. It is the first event
with simultaneous IR observations (GCN 2870, Blake and Bloom) and there
has been a near-threshold detection in the optical (GCN 2889, Wren et
al.). Given the large interest in this burst and the scientific value of
combining the simultaneous gamma-ray and ground observations, we provide
at the web site below the GRB041219 4-channel data (15-25 keV, 25-50 keV,
50-100 keV, 100-350 keV) for -341 s before to +558 s after the BAT trigger
with 0.064 s resolution. Provided are figures for each energy band, the 15
- 350 keV energy band, and a text table of the data. We have not corrected
for the deadtime. Testing has shown that our saturation level is > 1E6 Hz,
so we were orders of magnitude below our saturation limit.

The background was very smooth before the event and, apparently, also
within the 8 minute long burst. Beyond 560 s after the trigger, there is a
long smooth increase in the count rate, but it does not image to a point
source, so it is probably due to trapped radiation. We used 300 s of data
ending at 41 s before the trigger to determine background. Many features
are common to other GRBs: peaks that are narrower at higher energy, peaks
with FWHM of ~ 1 s, and a general softening of the event with time. Time in
the figure is from the BAT initial trigger at 6138.68 UT. BAT located
the event 14 s later, at which time Swift would have slewed XRT and UVOT
as well as sent out a TDRSS notice if slewing and TDRSS messages had been
enabled.

See http://gcn.gsfc.nasa.gov/gcn/other/041219_swift_bat.html