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GCN Circular 36553

Subject
GRB 240527B: Fermi GBM Observation
Date
2024-05-28T03:01:00Z (2 months ago)
From
Cori Fletcher at USRA <cfletcher@usra.edu>
Via
Web form
C. Fletcher (USRA) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 14:03:51.50 UT on 27 May 2024, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 240527B (trigger 738511436/240527586).
which was also detected by Fermi LAT (R. Gupta et al. 2024, GCN 36550).
The Fermi GBM on-ground location (GCN 36546) is consistent with the Fermi LAT position.

The angle from the Fermi LAT boresight is 78 degrees.

The GBM light curve consists of multiple peaks with a duration (T90)
of about 24.8 s (50-300 keV). The time-averaged spectrum
from T0+0.003 to T0+29.440 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -1.07 +/- 0.03 and the cutoff energy,
parameterized as Epeak, is 280 +/- 20 keV.

The event fluence (10-1000 keV) in this time interval is
(1.46 +/- 0.04)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+14 s in the 10-1000 keV band is 10.9 +/- 0.3 ph/s/cm^2.

A Band function fits the spectrum equally well 
with Epeak= 201 +/- 20 keV, alpha = -0.95 +/- 0.05 and beta = -2.1 +/- 0.1. 

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

"At 14:03:51.50 UT on 27 May 2024, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 240527B (trigger 738511436/240527586).
which was also detected by Fermi LAT (R. Gupta et al. 2024, GCN 36550).
The Fermi GBM on-ground location (GCN 36546) is consistent with the Fermi LAT position.

The angle from the Fermi LAT boresight is 78 degrees.

The GBM light curve consists of multiple peaks with a duration (T90)
of about 24.8 s (50-300 keV). The time-averaged spectrum
from T0+0.003 to T0+29.440 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -1.07 +/- 0.03 and the cutoff energy,
parameterized as Epeak, is 280 +/- 20 keV.

The event fluence (10-1000 keV) in this time interval is
(1.46 +/- 0.04)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+14 s in the 10-1000 keV band is 10.9 +/- 0.3 ph/s/cm^2.

A Band function fits the spectrum equally well 
with Epeak= 201 +/- 20 keV, alpha = -0.95 +/- 0.05 and beta = -2.1 +/- 0.1. 

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/"
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