[vsnet-grb-info 20937] GRB 180723A: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23035
SUBJECT: GRB 180723A: Fermi GBM detection
DATE:    18/07/25 02:37:32 GMT
FROM:    Suraj Poolakkil at UAH  <sp0076 at uah.edu>

S.Poolakkil and C. Meegan (both UAH) report on
behalf of the Fermi GBM Team:

"At 18:09:48.16 UT on 23 July 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180723A (trigger 554062193/ 180723757).

The on-ground calculated location, using the GBM trigger
data, is RA = 7.84, DEC = -66.11, with an uncertainty
of 1 degree (radius, 1-sigma containment,
statistical only; 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
at the GBM trigger time is 132 degrees.

The GBM light curve consists of a single bright peak
with a duration (T90) of about 19.71 s (50-300 keV).
The time-averaged spectrum from T0-2.05 s to T0+31.74 s is
best fit by a power-law function with an exponential
high-energy cutoff. The power law index is -1.22 +/- 0.02 and
the cutoff energy, parameterized as Epeak, is 178 +/- 5 keV.

The event fluence (10-1000 keV) in this time interval is
(4.616 +/- 0.057)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+3.39 s in the 10-1000 keV band
is 41.2 +/- 0.81 ph/s/cm^2.

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