GCN Circular 17508

O.J Roberts (UCD) reports on behalf of the Fermi GBM Team:

"At 04:53:25.04 UT on the 28th of February 2015, the Fermi
Gamma-Ray Burst Monitor triggered (446792008/150228204)
on a burst from magnetar 4U 0142+61, which was also
reported by Barthelmy et al. (GCN 17507
Not found
 
 
). The GBM on-ground
location is consistent with the known source position.

The triggered event consists of 4-5 bursts, each with a
duration of about 0.1s, that occur over a duration of about
20s. The two brightest bursts occur at T0-0.06s and T0+10.0s.
The burst at T0+10s is well-fit with a power law function with
an exponential high-energy cutoff. The power law index is
-0.38 +/- 0.33 and the cutoff energy, parameterised as Epeak,
is 74 +/- 8 keV. The fluence during T0+10.048s to T0+10.304s
is (2.703 +/- 0.384)E-07  erg/cm^2. The corresponding peak
flux integrated over 16ms (10-1000 keV) is
(11 +/- 1)E-06  ph/s/cm^2. The second burst at T0-0.064s is
best fit by a power law function with an exponential high-energy
cutoff. The power law index is -0.31 +/- 0.39 and the cutoff
energy, parameterised as Epeak, is 55 +/- 5 keV. The fluence
during T0-0.064s to T0+0.064s is (2.716 +/- 0.241)E-07 erg/cm^2.
The corresponding peak flux integrated over 16ms (10-1000 keV)
is (18 +/- 1)E-06  ph/s/cm^2.

This burst was followed by another trigger at 05:06:55.63 UT
(trigger 446792818/150228213) on the 28th of February 2015,
and is also consistent with being from magnetar 4U 0142+61.
This trigger consists of a bright, short (t<~0.3s) single peak.

The analysis results presented above are preliminary.

These bursts are bright enough that some are being classified by
the flight software as GRBs. We will correct this classification
in the online catalogue at the Fermi Science Support Center:

http://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigtrig.html

but will not issue individual circulars to correct the classification
for triggers from this source."