TITLE: GCN CIRCULAR NUMBER: 36553 SUBJECT: GRB 240527B: Fermi GBM Observation DATE: 24/05/28 03:01:00 GMT FROM: Cori Fletcher at USRA <cfletcher@usra.edu> 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/" View this GCN Circular online at https://gcn.nasa.gov/circulars/36553. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...