TITLE:   GCN CIRCULAR
NUMBER:  36685
SUBJECT: GRB 240615A: Fermi GBM Observation
DATE:    24/06/17 14:47:05 GMT
FROM:    Oliver J Roberts at USRA/NASA <oliver.roberts@nasa.gov>

O.J. Roberts (USRA/NASA-MSFC) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 17:51:45.05 UT on 15 June 2024, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 240615A (trigger 740166710/240615744), which was 
also detected by Swift BAT GUANO (DeLaunay et al. 2024, GCN 36672), 
KONUS-WIND (Frederiks et al. 2024, GCN 36677) and GECAM (Tan et al. 2024, GCN 36682). 
The Fermi-GBM Final Real-time location (Fermi GBM Team 2024, GCN 36671) 
is consistent with the Swift BAT-GUANO position.

The angle from the Fermi LAT boresight is 23 degrees.

The GBM light curve consists of bright, overlapping emission episodes with a 
duration (T90) of about 0.10 s (50-300 keV). The time-averaged spectrum
from T0-0.03 to T0+0.09 s is best fit by a power law function with an 
exponential high-energy cutoff. The power law index is -0.52 +/- 0.07 
and the cutoff energy, parameterized as Epeak, is 933 +/- 105 keV.

A Band function fits the spectrum equally well with Epeak= 858 +/- 110 keV, 
alpha = -0.48 +/- 0.08 and beta = -3.04 +/- 0.76. 

The event fluence (10-1000 keV) in this time interval is
(1.56 +/- 0.06)E-06 erg/cm^2. The 64-ms peak photon flux measured
starting from T0+0.0 s in the 10-1000 keV band is 45 +/- 2 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/"