GCN Circular 44564
Subject
GRB 260510C: Fermi GBM Observation
Event
Date
2026-05-11T20:51:58Z (4 days ago)
From
Eva MP at INAOE <eva.palafox@gmail.com>
Via
Web form
E. Palafox (INAOE, Mexico) reports on behalf of the Fermi Gamma-ray Burst Monitor Team:
"At 17:13:43.99 UT on 10 May 2026, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 260510C (trigger 800126028/260510718),
which was also detected by SVOM/ECLAIRs (Gotz et al. 2026, GCN 44521),
MAXI (Iwakiri et al. 2026, GCN 44526), COLIBRI (Angulo et al. 2026, GCN 44530),
SVOM/VT (Li et al. 2026, GCN 44527 and GCN 44540), EP-FXT (Fu et al. 2026, GCN 44541)
and AstroSat CZTI (Arya et al. 2026,GCN 44544).
The Fermi GBM on-ground location is consistent with the SVOM/ECLAIRs position.
The angle from the Fermi LAT boresight is 68 degrees.
The GBM light curve consists of two bright emission episodes with a duration (T90)
of about 162 s (50-300 keV). The time-averaged spectrum
from T0-8.2 to T0+143.4 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -1.3 +/- 0.2 and the cutoff energy,
parameterized as Epeak, is 176 +/- 55 keV.
The event fluence (10-1000 keV) in this time interval is
(4.9 +/- 0.7)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+120 s in the 10-1000 keV band is 2.6 +/- 0.3 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/"