GCN Circular 22759

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

"At 22:31:05.34 UT on 02 June 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180602B (trigger 549671470/ 180602938).

The on-ground calculated location, using the GBM trigger
data, is RA = 86.05, DEC = -62.78, with an uncertainty
of 2 degrees (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 9 degrees.

The GBM light curve consists of a single bright peak
with a duration (T90) of about 0.01 s (50-300 keV).
The time-averaged spectrum from T0-0.06 s to T0+0.06 s is
best fit by a power-law function with an exponential
high-energy cutoff. The power law index is -0.68 +/- 0.18 and
the cutoff energy, parameterized as Epeak, is 395 +/- 105 keV.

The event fluence (10-1000 keV) in this time interval is
(3.0 +/- 0.4)E-07 erg/cm^2. The 64 ms peak photon flux measured
starting from T0-0.06 s in the 10-1000 keV band
is 14 +/- 1 ph/s/cm^2.

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