GCN Circular 34094

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

"At 14:30:22.25 UT on 26 June 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB230626A (trigger 709482627/230626604).

The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 146.38, Dec = 0.09 (J2000 degrees, equivalent to
J2000 09h 45m, +00d 05'), with a statistical uncertainty of 1.0 degrees.
(radius, 1-sigma containment, statistical only; there is additionally a
systematic error which we have characterized as a core-plus-tail model,
with 90% of GRBs having a 3.7 deg error and a small tail suffering a larger
than 10 deg systematic error [Connaughton et al. 2015, ApJS, 216, 32]).

The angle from the Fermi LAT boresight is 49 degrees.

The GBM light curve consists of two peaks (the second peak is found
to be much brighter) with a duration (T90) of about 15 s (50-300 keV).
The time-averaged spectrum from T0-1.024 to T0+25.60 s is best fit by
a Band function with Epeak= 169 +/- 12 keV, alpha = -1.29 +/- 0.02
 and beta = -2.16 +/- 0.08.

The event fluence (10-1000 keV) in this time interval is
(2.55 +/- 0.04)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+11 s in the 10-1000 keV band is 35 +/- 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/"