Fermi GBM detects long GRB 260307A with multi-peaked structure

AI Summary

Fermi GBM and CALET detected a long gamma-ray burst (GRB 260307A) with a multi-peaked structure. MASTER-Kislovodsk provided early optical upper limits.

Notices (2)

Fermi — GRB · Sat, 07 Mar 2026 05:57:59 GMT

Unknown — OTHER · Sat, 07 Mar 2026 05:57:59 GMT

GCN Circulars (4)

GCN-43982 — GRB 260307A · Fri, 13 Mar 2026 10:45:12 GMT
The CALET Gamma-Ray Burst Monitor detected a long gamma-ray burst, GRB 260307A, on March 7, 2026. The burst had a multi-peaked structure, with T90 and T50 durations of 4.6 +/- 0.5 sec and 2.0 +/- 0.2 sec, respectively. The event was also observed by other telescopes and collaborations, including Fermi GBM and Glowbug.

GCN-43950 — GRB 260307A · Mon, 09 Mar 2026 20:35:59 GMT
The Glowbug gamma-ray telescope on the International Space Station has confirmed the detection of GRB 260307A, which was previously detected by Fermi/GBM and CALET. The burst occurred on 2026-03-07 at 11:27:59.2 with a duration of 5.0 seconds.

GCN-43944 — GRB 260307A · Sun, 08 Mar 2026 03:00:45 GMT
The MASTER-Kislovodsk robotic telescope in Russia began observing Fermi GRB 260307A 52 seconds after the gamma-ray burst was detected by the Fermi GBM team. The observations, which are ongoing, have yielded upper limits on the brightness of the burst in the clear filter, ranging from 12.1 to 17.6 magnitudes.

GCN-43939 — GRB 260307A · Sat, 07 Mar 2026 13:08:25 GMT
The Fermi Gamma-ray Burst Monitor (GBM) has detected and localized a long gamma-ray burst (GRB 260307A) at a position RA = 209.07, Dec = 29.03 (J2000) with a statistical uncertainty of 2.88 degrees. The burst occurred on March 7, 2026, at 11:27:59.32 UT. The angle from the Fermi LAT boresight is 77 degrees. The data and associated files can be accessed through various links.