GCN Circular 35590

Wen-Long Zhang, Shao-Lin Xiong, Yan-Qiu Zhang report on behalf of the GECAM team:

GECAM-B was triggered on-ground by a long burst, GRB 240118C, at 2024-01-18T17:23:24.000 UTC (T0), which was also observed by Fermi/GBM (GCN #35576 and GCN #35586) and Swift/BAT-GUANO（GCN #35581）. 

According to the GECAM-B light curve, this burst consists of  roughly three pulses with a total duration of ~40 sec. 

The GECAM-B ground calculated location (J2000) is:
Ra: 308.64 deg   
Dec: -1.56 deg
Err: 4.65 deg (1-sigma, statistical only)
This GECAM-B localization is consistent with that of 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 Dec. 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).