TITLE:   GCN CIRCULAR
NUMBER:  43144
SUBJECT: GRB 251215A: Fermi GBM Observation
DATE:    25/12/16 18:31:35 GMT
FROM:    Peter Veres at University of Alabama in Huntsville <veresp@gmail.com>

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

"At 04:21:21.57 UT on 15 December 2025, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 251215A (trigger 787465286/251215181),
which was also detected by Swift-BAT-GUANO (Ronchini et al. 2025, GCN 43114), Swift-XRT (Osborne et al. 2025, GCN 43137) and Glowbug (Cheung et al. 2025, GCN 43133).
The real-time  Fermi GBM location (GCN 43104) is consistent with the Swift-BAT position.

The GBM light curve consists of multiple overlapping pulses with a duration (T90)
of about 143 s (50-300 keV). The time-averaged spectrum
from T0-37 to T0+162 s is best fit by
a Band function with Epeak = 35 +/- 7 keV,
alpha = -1 +/- 0.3, and beta = -1.97 +/- 0.03.

The event fluence (10-1000 keV) in this time interval is
(2.05 +/- 0.06)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+64 s in the 10-1000 keV band is 5.7 +/- 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/"