[vsnet-grb-info 18276] GRB 160720A: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  19724
SUBJECT: GRB 160720A: Fermi GBM detection
DATE:    16/07/21 01:53:43 GMT
FROM:    Rachel Hamburg at UAH  <rkh0007 at uah.edu>

R. Hamburg (UAH) and E. Burns (UAH)
report on behalf of the Fermi GBM Team:

"At 18:23:57.00 UT on 20 July 2016, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 160720A (trigger 490731840 / 160720767).
The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 43, Dec = +76, with a statistical uncertainty of 1.00 degrees;
there is additionally a systematic error
which we have characterized as a core-plus-tail model, with 90% of GRBs
having a
3.7 deg error and a small tail suffering a larger than 10 deg systematic
error.
[Connaughton et al. 2015, ApJS, 216, 32].
The angle from the Fermi LAT boresight is 131 degrees.

The GBM light curve consists of several overlapping peaks with a duration
(T90)
of about 79 s (50-300 keV). The time-averaged spectrum from T0-1.02 to
T0+154 s is best fit by a power law function with an exponential
high-energy cutoff. The power law index is -1.12 +/- 0.01 and
the cutoff energy, parameterized as Epeak, is 191 +/- 3 keV.

The event fluence (10-1000 keV) in this time interval is (151 +/- 1)E-06
erg/cm^2. The 1-sec peak photon flux measured starting from T0+88 s in the
10-1000 keV band is 58 +/- 1 ph/s/cm^2.

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