TITLE:   GCN CIRCULAR
NUMBER:  35763
SUBJECT: GRB 240215B: Fermi GBM Observation
DATE:    24/02/20 16:45:45 GMT
FROM:    Lorenzo Scotton at UAH <lscottongcn@outlook.com>

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

"At 19:51:43.85 UT on 15 February 2024, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 240215B (trigger 729719508/240215828),
which was also detected by Swift/BAT-GUANO (J. DeLaunay et al. 2024, GCN 35739), 
and GRBAlpha (A. Pal et al. 2024, GCN 35752).
The Fermi GBM Final Real-time Localization was reported in GCN 35740, 
but was mislabelled as GRB 240215C.
After manual inspection, a more accurate on-ground location was found to be 
RA = 309.52, Dec = -48.74, with a statistical uncertainty of 2.54 degrees.

The angle from the Fermi LAT boresight is 94 degrees.

The GBM light curve consists of a single emission episode with a duration (T90)
of about 21 s (50-300 keV). The time-averaged spectrum
from T0-5.5 to T0+21.5 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -1.16 +/- 0.04 and the cutoff energy,
parameterized as Epeak, is 210 +/- 10 keV.

The event fluence (10-1000 keV) in this time interval is
(1.12 +/- 0.04)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+4.9 s in the 10-1000 keV band is 10.8 +/- 0.4 ph/s/cm^2.

A Band function fits the spectrum equally well
with Epeak= 190 +/- 20 keV, alpha = -1.13 +/- 0.05 and beta = -2.5 +/- 0.3.

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/"