TITLE:   GCN CIRCULAR
NUMBER:  21812
SUBJECT: GRB 170903A: Fermi GBM observation
DATE:    17/09/04 19:48:16 GMT
FROM:    Bill Paciesas at UAH  <bill.paciesas@nasa.gov>

F. Berlato (MPE) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 12:49:07.79 UT on 3 September 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170903A (trigger 526135752 / 170903534), which
was also detected by the Swift/BAT (Markwardt et al., GCN 21793).

The GBM on-ground localization is consistent with the Swift location.

The angle from the Fermi LAT boresight at the GBM trigger time is 93 degrees.

The GBM light curve shows two pulses with a duration (T90) of 
about 25 s (50-300 keV). The time-averaged spectrum from 
T0-1.5 s to T0+25.5 s is adequately fit by a Comptonized model, 
with index  -1.56 +/- 0.10 and Epeak 124 +/- 33 keV .
The event fluence (10-1000 keV) in the time interval is 
(4.34 +/- 0.54)E-06 erg/cm^2. The 1-sec peak photon flux (10-1000 keV) 
measured starting from T0-1.5 s is (5.80 +/- 0.36) ph/s/cm^2.

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