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GCN Circular 12331

Subject

MAXI J1836-194 (originally GRB 110905A): Swift-BAT refined analysis

Date

2011-09-05T17:40:23Z (14 years ago)

From

Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>

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),
D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC)
(i.e. the Swift-BAT team):
 
Using the data set from T+592 to T+963 sec from recent telemetry downlinks,
we report further analysis of BAT trigger #502415 (Pagani, et al.,
GCN Circ. 12327Loading...
 
 ).  The BAT ground-calculated position is
RA, Dec = 278.958, -19.269 deg, which is 
   RA(J2000)  =  18h 35m 49.9s 
   Dec(J2000) = -19d 16' 07.5" 
with an uncertainty of 3.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.
 
Because this was a long image trigger (26 minutes), the event-by-event data
just before, during, and for 592 sec after the trigger time was overwritten
in the ring buffer,  and as such, it is not possible to construct a lightcurve
for the early phase of this event.  Starting at T+590, the lightcurve
shows a low-level persistant emission out to T+963 sec.
 
The time-averaged spectrum from T+590 to T+963 sec can be fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.53 +- 0.39.  The fluence in the 15-150 keV band is 7.8 +- 2.0 x 10^-7 erg/cm2.
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/502415/BA/

Given the (a) the long and constant hard x-ray emission (in the later phase)
of this event, (b) the proximity to the Galactic Bulge, (c) the proximity
to the MAXI J1836-194; we believe this trigger to be due to the MAXI source
and not due to a GRB (as has been pointed out by J.Greiner (pri.comm.) and
D.Fox (GCN 12329Loading...
 
 )).