GCN Circular 33438

Zhentong Li, Yang Su on behalf of the HXI team report:

At 2023-03 07 15:44:09 UT, HXI detected the bright GRB 230307A  (Burns et al. GCNC 33414) which was also reported by Fermi/GBM (Fermi GBM Team et al.  GCNC 33405; Dalessi, GCNC 33407; Dalessi et al. , GCNC 33411;  Dalessi et al. GCNC 33411),  GECAM (Xiong et al. GCNC 33406), STIX (Xiao et al. GCNC 33410), AGILE/MCAL (Claudio et al. GCNC 33412), IPN (Kozyrev et al. GCNC 33413, Kozyrev et al. GCNC 33425),  AstroSat CZTI (Gaurav et al. GCNC 33415),  BARLOG (Jochen et al. GCNC 33416),  GRBAlpha (Marianna et al. GCNC 33418), VZLUSAT-2 (Ripa et al. GCNC 33424),  Konus-WIND (Svinkin et al. GCNC 33427),  Swift (Phil et al. GCNC 33419, GCNC 33431),  IceCube (Jessie et al. GCNC 33430) and BOOTES (Alberto et al. GCNC 33434). 

The GRB signal is spiky with significant responses at energies from ~20 keV to the detection upper limit 300 keV of the HXI scintillation detectors. The signal displays a major peak (> 570 cts/s/detetor) and a faint secondary peak (> 230 cts/s/detetor, with an in-orbit background of ~130 cts/s/detetor). The duration of the major peak is ~16 s and the whole signal lasts for ~40 s. The time resolution of the observed signal is 4 s. The burst mode (res. as high as 0.125s) was not triggered because the GRB was detected by both total flux monitor and background monitor.

By examining the count rate distribution of the 99 detectors of HXI, the direction of the GRB was roughly deduced. Hard X-ray Imager (HXI) is one of the three scientific payloads onboard the Advanced Space-based Solar Observatory (ASO-S) satellite, which is China���s first comprehensive solar dedicated space science mission. HXI is designed to investigate the non-thermal high-energy electrons accelerated in solar flares by providing X-ray spectra and images of solar flaring regions in the energy range from 15 to 300 keV. ��It started to work on ��2022-Oct-17 and is currently in the inflight testing phase. The science data will be completely open to the community after the testing phase, i.e., around mid-April 2023.

More information about HXI can be found on the ASO-S website: http://aso-s.pmo.ac.cn/en_index.jsp