TITLE:   GCN CIRCULAR
NUMBER:  30380
SUBJECT: GRB 210704A: Fermi GBM detection
DATE:    21/07/05 17:43:24 GMT
FROM:    Christian Malacaria at NASA-MSFC/USRA  <cmalacaria@usra.edu>

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

"At 19:33:24.59 UT on 04 July 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210704A (trigger 647120009 / 210704815),
which was also detected by Fermi-LAT (Berretta et al. 2021, GCN 30375), 
AGILE/MCAL (Ursi et al. 2021, GCN 30372), AstroSat/CZTI (Prasad et al. 2021, GCN 30378)
and Swift/XRT (D'Ai et al. 2021, GCN 30379).

The Fermi-GBM on-ground calculated location is consistent with the Swift/XRT position.
The angle from the Fermi LAT boresight at the GBM trigger time is 63 degrees.

The GBM light curve consists of a main bright peak
with a duration (T90) of about 4.7 s (50-300 keV).
The time-averaged spectrum from T0+0.2 s to T0+1.8 s is
best fit by a Band function with Epeak = 286.1 +/- 6.4 keV,
alpha = -0.35 +/- 0.02, and beta = -2.91 +/- 0.12 .

The event fluence (10-1000 keV) in this time interval is
(1.95 +/- 0.02)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.5 s in the 10-1000 keV band
is 75.9 +/- 0.5 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/"