TITLE:   GCN CIRCULAR
NUMBER:  30279
SUBJECT: GRB 210619B: Fermi GBM detection
DATE:    21/06/20 18:40:56 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 23:59:25.60 UT on 19 June 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210619B (trigger 645839970 / 210619999)
which was also detected by the Swift/BAT (D'Avanzo et al. 2021, GCN 30261),
Fermi-LAT (Axelsson et al. 2021, GCN 30270) and Konus-Wind (Svinkin et
al. 2021, GCN 30276).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 109 degrees.

The GBM light curve consists of a single peak followed by some
extended emission with a duration (T90) of about 55 s (50-300 keV).
The time-averaged spectrum from T0 s to T0+61.4 s
is best fit by a Band function, with Epeak = 210 +/- 3 keV,
alpha = -0.86 +/- 0.01 and beta = -1.99 +/- 0.01.

The event fluence (10-1000 keV) in this time interval is
(307.93 +/- 0.9830)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.51 s in the 10-1000 keV band
is 238.6 +/- 1.3 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/"