GRB 260303B detected by multiple instruments with significant gamma-ray emission.

AI Summary

GRB 260303B, detected by Fermi GBM, AstroSat CZTI, and NuSTAR, exhibited strong gamma-ray emission with a T90 of 11 seconds and peak count rates exceeding 59 counts/s. Follow-up observations provided precise localization and upper limits on optical counterparts.

Notices (2)

Fermi — GRB · Tue, 03 Mar 2026 07:54:20 GMT

Unknown — OTHER · Tue, 03 Mar 2026 07:54:20 GMT

GCN Circulars (5)

GCN-43919 — GRB 260303B · Wed, 04 Mar 2026 19:43:04 GMT
Astronomers using the AstroSat CZTI collaboration have detected a long gamma-ray burst (GRB 260303B) in the 20-200 keV energy range. The burst was also detected by Fermi GBM and NuSTAR. The peak count rate was measured to be 59 counts/s above the background, with a total of 504 counts and a T90 of 11 seconds. The source was also faintly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range.

GCN-43914 — GRB 260303B · Tue, 03 Mar 2026 19:20:30 GMT
The NuSTAR SINGS working group has detected prompt emission from long-duration gamma-ray burst (GRB) 260303B using NuSTAR CsI shield data. The detection occurred on March 3, 2026, and the emission lasted for approximately 20 seconds with a peak count rate of ~1500 cps and a baseline rate of ~1000 cps. The GRB was identified through a blind search and was located at RA = 9.3, Dec = -26.7, with an offset from the NuSTAR boresight of 92 degrees and an offset from the geocenter of 159 degrees.

GCN-43912 — GRB 260303B · Tue, 03 Mar 2026 19:17:13 GMT
The MASTER-SAAO robotic telescope in South Africa observed Fermi GRB 260303B, reporting upper limits on magnitudes ranging from 15.8 to 16.5 in clear filter, 60 seconds after the trigger time. The observations began at a zenith distance of 82 degrees and galactic coordinates b=-87 deg., l=48 deg.

GCN-43908 — GRB 260303B · Tue, 03 Mar 2026 14:05:07 GMT
A gamma-ray burst (GRB) with the designation GRB 260303B, also known as Fermi Trigger 794237065 and GRB 260303559, was localized by the BALROG algorithm. The best-fit position is at RA(2000.0) = 13.0 degrees and Decl.(2000.0) = -27.8 degrees, with a statistical error radius of 1.3 degrees and a systematic error of 1 degree.

GCN-43907 — GRB 260303B · Tue, 03 Mar 2026 13:34:53 GMT
The Fermi Gamma-ray Burst Monitor (GBM) has detected and located a long gamma-ray burst, GRB 260303B, at coordinates RA = 9.3, Dec = -26.7 (J2000) with a statistical uncertainty of 1.6 degrees. The angle from the Fermi Large Area Telescope (LAT) boresight is 67.0 degrees.