TITLE:   GCN CIRCULAR
NUMBER:  30209
SUBJECT: GRB 210605B: Fermi GBM detection
DATE:    21/06/11 20:57:40 GMT
FROM:    Suraj Poolakkil at UAH  <sp0076@uah.edu>

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

"At 14:55:58.08 UT on 5 June 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210605B (trigger 644597763 / 210605622)
which was also detected by the Swift/BAT-GUANO (DeLaunay et al. 2021, GCN
30130)
The Fermi GBM Final Real-time Localization (GCN 30129) is consistent with
the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 19
degrees.

The GBM light curve consists of multiple peaks followed by some
extended emission with a duration (T90) of about 110 s (50-300 keV).
The time-averaged spectrum from T0-3.07 s to T0+113.66 s
is best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.78 +/- 0.08  and
the cutoff energy, parameterized as Epeak, is 150 +/- 11 keV.

The event fluence (10-1000 keV) in this time interval is
(10.12 +/- 0.44)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+26.36 s in the 10-1000 keV band
is 3.3 +/- 0.2 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support
Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"