[vsnet-grb-info 16453] GRB 150422A: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17734
SUBJECT: GRB 150422A: Fermi GBM detection
DATE:    15/04/23 14:35:44 GMT
FROM:    George A. Younes at USRA/NASA/MSFC  <younes.ge at gmail.com>

George Younes (USRA at GWU) and Charles Meegan (UAH) report on behalf of the Fermi GBM Team:

"At 16:52:33.99  on April 22 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 150422A (trigger 451414356/150422703).
The GBM on-ground location, using the Fermi GBM trigger
data, is RA = 215.1, Dec = -20.9 (J2000 degrees, equivalent to
14h 20m 24s, -20d 54’), with an uncertainty of 1.1
degrees (radius, 1-sigma containment,statistical
only; there is additionally a systematic error which is
currently estimated to be 2 to 3 degrees).

The angle of the burst direction to the Fermi LAT boresight is
57 degrees.

The trigger resulted in an Autonomous Repoint Request (ARR) that was accepted and the
spacecraft slewed to the GBM in-flight location.

The GBM light curve consists of multiple peaks with a duration
(T90) of about 37 s (50-300 keV).
The time-averaged spectrum from T0+0s to T0+49.2s
is well fit by a BAND function with Epeak = 100 +/- 3 keV,
Alpha = -1.16 +/- 0.03 and Beta = -2.35 +/- 0.05.
The event fluence (10-1000 keV) in this time interval is
(3.40 +/- 0.04)E-05 erg/cm^2. The 1.0-sec peak photon flux measured
starting from T0+11.6 s in the 10-1000 keV band
is 17.0 +/- 0.4 ph/s/cm^2.


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