TITLE:   GCN CIRCULAR
NUMBER:  33931
SUBJECT: GRB 230606A: Fermi GBM Observation
DATE:    23/06/06 20:43:59 GMT
FROM:    Sarah Dalessi at UAH <sd0104@uah.edu>

S. Dalessi (UAH) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team:

"At 00:14:38.13 UT on 06 June 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230606A (trigger 707703283/230606010).
which was also detected by Swift BAT (A. Y. Lien et al. 2023, GCN 33921).
The Fermi GBM on-ground location is consistent with the Swift BAT position.

The angle from the Fermi LAT boresight is 110 degrees.

The GBM light curve consists of multiple peaks with a duration (T90)
of about 16 s (50-300 keV). The time-averaged spectrum
from T0-1.8 to T0+18.7 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -0.7 +/- 0.2 and the cutoff energy,
parameterized as Epeak, is 148 +/- 22 keV.

The event fluence (10-1000 keV) in this time interval is
(2.5 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+2.4 s in the 10-1000 keV band is 3.4 +/- 0.3 ph/s/cm^2.

A Band function fits the spectrum equally well
with Epeak= 98 +/- 25 keV, alpha = -0.2 +/- 0.5 and beta = -2.1 +/- 0.2.

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/"