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GCN Circular 12187

GRB 110721A: Fermi GBM detection
2011-07-21T11:17:24Z (13 years ago)
David Tierney at UCD <>
D. Tierney (UCD) and A. von Kienlin (MPE)
report on behalf of the Fermi GBM Team: 

"At 04:47:43.75 UT on 21 July 2011, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 110721A (trigger 332916465 / 110721200).

The on-ground calculated location, using the GBM trigger 
data, is RA = 331.42, DEC = -36.42 (J2000 degrees, 
equivalent to 22h 05m, -36d 25'), with an uncertainty 
of 1.00 degree (radius, 1-sigma containment, 
statistical only; there is additionally a systematic
error which is currently estimated to be 2 to 3 degrees).
The angle from the Fermi LAT boresight is 43.00 degrees.

The GBM light curve consists of a fast rise, exponential decay (FRED)
with a duration (T90) of  24.45 s (50-300 keV). 
The time-averaged spectrum from T0-0.32 s to T0+11.97 s is 
best fit by a Band function with Epeak = 372.50 (+26.50/-23.60) keV, 
alpha = -0.94 (+/-0.02), and beta = -1.77 (+/-0.02)
(C-Stat 945.78 for 591 d.o.f.).

The event fluence (10-1000 keV) in this time interval is 
(3.52 +/- 0.03)E-05 erg/cm^2. The 1-sec peak photon flux measured 
starting from T0+1.98 s in the 10-1000 keV band 
is 31.35 +/- 0.38 ph/s/cm^2.

The spectral analysis results presented above are preliminary; 
final results will be published in the GBM GRB Catalog."
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