GRB 261005B: Multi-peaked gamma-ray burst detected by Fermi GBM and Swift BAT

AI Summary

Fermi GBM triggered on a gamma-ray burst (GRB 261005B, trigger 812929158) at 2026-10-05T21:39:13.77Z, with a duration of ~22 seconds and peak photon flux of 1.56 ph/s/cm². The burst spectrum is well-fit by a power law with exponential cutoff (index -0.56, Epeak = 110 keV) and fluence of 8×10⁻⁷ erg/cm². Swift BAT independently detected the same event with consistent multi-peaked structure lasting ~40 seconds. Swift-XRT provided a refined position (RA 255.339°, Dec 1.589°, 2.2 arcsec uncertainty), enabling precise localization for follow-up observations.

Measurements

Notices (1)

Fermi GBM — GRB · Mon, 05 Oct 2026 21:39:13 GMT

GCN Circulars (3)

GCN-45816 — GRB 261005B · Tue, 06 Oct 2026 04:28:59 GMT
On 05 October 2026, the Fermi Gamma-ray Burst Monitor (GBM) detected a gamma-ray burst (GRB 261005B) that was also observed by the Swift BAT. The event lasted approximately 22 seconds and had a peak photon flux of 1.56 ph/s/cm2, with a preliminary spectral analysis indicating a power law index of -0.56 and a cutoff energy of 110 keV.

GCN-45815 — GRB 261005B · Tue, 06 Oct 2026 04:17:08 GMT
The Swift-XRT team has reported an enhanced X-ray position for the gamma-ray burst GRB 261005B, with coordinates RA (J2000): 17 01 21.42, Dec (J2000): +01 35 19.4, and an uncertainty of 2.2 arcsec. This position is derived from 1707 seconds of XRT Photon Counting mode data and 3 UVOT images, and may be further refined with additional data.

GCN-45812 — GRB 261005B · Mon, 05 Oct 2026 22:04:52 GMT
The Swift Burst Alert Telescope detected a gamma-ray burst, GRB 261005B, on October 26, 2005, at 21:39:06 UT. The burst had a multi-peaked structure lasting about 40 seconds and a peak count rate of approximately 2000 counts/sec. Swift's X-ray Telescope (XRT) began observing the field shortly after but did not detect a source in the initial image.