GCN Circular 35689

Wen-Long Zhang, Shao-Lin Xiong, Chen-Wei Wang report on behalf of the GECAM team:

GECAM-B was triggered in-flight by a long burst, GRB 240205B, at 2024-02-05T22:13:08.400 UTC (T0), which was also detected by Fermi/GBM (GCN #35682), Swift/BAT (GCN #35683), INTEGRAL_SPIACS (trig# 10513) and CALET/GBM (trig# 1391206207). As the science data arrived, GECAM-B was also triggered on-ground by this burst with the automatic processing pipeline. 

According to the GECAM-B light curves, this burst shows multi-pulses with a total duration of ~50 sec. Interestingly, we note that there is a bright and narrow peak at T0+ 37.5 s.

According to the in-flight software, GECAM-B localized this burst to the following position (J2000): 
Ra: 344.14 deg   	
Dec: -53.02 deg
Err: 8.74 deg (1-sigma, statistical only)
This GECAM-B localization is consistent with that of Swift/BAT and Fermi/GBM within the error.

We note that these results are very preliminary. Refined analysis will be reported later.

Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission originally consists of two microsatellites (GECAM-A and GECAM-B) launched in December 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS).