TITLE:   GCN CIRCULAR
NUMBER:  27260
SUBJECT: GRB 200228A: Fermi GBM observation
DATE:    20/02/28 17:03:56 GMT
FROM:    Elisabetta Bissaldi at INFN,Bari  <elisabetta.bissaldi@ba.infn.it>

E. Bissaldi (Politecnico and INFN Bari)
reports on behalf of the Fermi GBM Team:


"At 06:58:33.81 UT on 28 February 2020, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 200228A (trigger 604565918 / 200228291), as reported
by the Fermi GBM Final Real-time Localization (GCN 27247).
The GBM localization is consistent with the Swift GUANO localization
(Tohuvavohu et al. 2020, GCN 27259).

The angle from the Fermi LAT boresight at the GBM trigger time is 33 degrees.

The GBM light curve consists of a single bright peak
with a duration (T90) of about 4 s (50-300 keV).
The time-averaged spectrum from T0 to T0+4 s is
adequately fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.61 +/- 0.04 and
the cutoff energy, parameterized as Epeak, is 165 +/- 5 keV.

The event fluence (10-1000 keV) in this time interval is
(6.44 +/- 0.13)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+1.0 s in the 10-1000 keV band
is 20.4 +/- 0.4 ph/s/cm^2.

A Band function fits the spectrum equally well
with Epeak= 153 +/- 7 keV, alpha = -0.54 +/- 0.05 and
beta = -2.85 +/- 0.23.

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/"