[vsnet-grb-info 19599] Fermi GBM Detection of possible burst from AXP 4U 0142+61

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  21342
SUBJECT: Fermi GBM Detection of possible burst from AXP 4U 0142+61
DATE:    17/07/14 16:10:57 GMT
FROM:    Rachel Hamburg at UAH  <rkh0007 at uah.edu>

R. Hamburg (UAH) reports on behalf of the Fermi GBM Team:

"At 23:54:33.18 UT on 13 July 2017, the Fermi Gamma-Ray Burst Monitor
triggered (trigger 521682878 / 170713996) on a SGR-like burst.
The GBM on-ground location is consistent
with the position of the known source AXP 4U 0142+61, which was
previously observed by GBM on 28 February 2015 (Roberts 2015, GCN 17508).
This burst was bright enough that it was classified by
the flight software as a GRB; however, due to its location and soft
spectrum,
this trigger was reclassified as an SGR.

The GBM light curve shows one main peak and several smaller peaks following.
The main peak has a duration (T90) of about 0.1 s, and
the time-averaged spectrum from T0-0.064 to T0+0.064 is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.1 +/- 0.3 and
the cutoff energy, parameterized as Epeak, is 35 +/- 1 keV.
The spectrum is also well fit by an Optically Thin Thermal Bremsstrahlung
model with a temperature of 32 +/- 2 keV.

The event fluence (10-1000 keV) in this time interval is
(1.5 +/- 0.3)E-07 erg/cm^2. The photon flux measured starting
from T0-0.64 s in the 10-1000 keV band is 27 +/- 1 ph/s/cm^2.

The analysis results presented above are preliminary."