TITLE: GCN CIRCULAR NUMBER: 35755 SUBJECT: GRB 240218A: Fermi GBM Detection DATE: 24/02/19 01:21:14 GMT FROM: Peter Veres at University of Alabama in Huntsville <veresp@gmail.com> P. Veres and C. Meegan (both UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 02:00:21.72 UT on 18 February 2024, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 240218A (trigger 729914426/240218084), which was also detected by Swift/BAT (Page et al. 2024, GCN 35742). The Fermi GBM on-ground localization is consistent with the Swift BAT position. The angle from the Fermi LAT boresight is 93 degrees. The GBM light curve consists of a single pulse followed by weaker emission with a duration (T90) of about 38 s (50-300 keV). The time-averaged spectrum from T0-2.6 to T0+30.2 s is best fit by a Band function with Epeak = 100 +/- 20 keV, alpha = -0.3 +/- 0.3, and beta = -1.9 +/- 0.1. The event fluence (10-1000 keV) in this time interval is (5.2 +/- 0.4)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+1.5 s in the 10-1000 keV band is 3.1 +/- 0.2 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/" View this GCN Circular online at https://gcn.nasa.gov/circulars/35755. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...