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GCN Circular 33406

GRB 230307A: GECAM detection of an extremely bright burst
2023-03-07T16:53:45Z (a year ago)
Dong Xu at NAOC/CAS <>
Shaolin Xiong, Chenwei Wang, Yue Huang, report on behalf of the GECAM team:

GECAM-B was triggered in-flight by the extremely bright long burst at 
2023-03-07T15:44:06.650 UTC (T0), which was also observed by Fermi/GBM 
(GCN 33405).

The GECAM-B ground calculated location (J2000) is:

R.A.: 28.03 [deg]
Dec.: -81.51 [deg]
Error: 1 [deg] (1-sigma, statistical only)

The systematic error of this location is estimated to be ~2 degrees. 
This GECAM location is consistent with the Fermi/GBM one within error.

The GECAM-B light curve shows a roughly FRED shape with a possible 
precursor, with a total duration of ~100 sec. The time-averaged spectrum 
analysis on the trigger alert data shows this burst has a fluence of 
about 1E-3 erg/cm2 in 20-1000 keV, which is notably high, and comparable 
to GRB 130427A.  We caution that this analysis is very preliminary. 
Refined analysis will be reported later.

Follow-up observations are encouraged.
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