On-Orbit Performance Analysis of the Hard X-ray Imager (HXI) on the Advanced Space-Based Solar Observatory (ASO-S)

This study presents a detailed on-orbit performance analysis of the Hard X-ray Imager (HXI) aboard the Advanced Space-based Solar Observatory (ASO-S), confirming its overall stability within design specifications for key parameters like detection efficiency and energy resolution. However, the analysis focuses primarily on characterizing temporal variations, including distinct periodic fluctuations linked to orbital (∼ 99 minutes) and annual cycles, as well as non-periodic events. Temperature variations highlight orbital/seasonal effects and suggest potential long-term thermal leakage around the Solar Aspect System (SAS) via a gradual rise on the front plate. High-voltage (HV) remains stable during nominal operations, but its management during South Atlantic Anomaly (SAA) passages is critical. Gain analysis identifies a generally stable trend punctuated by five significant abrupt decreases attributed to operational parameter reset errors and radiation exposure during SAA passages (influenced by geomagnetic storms or operational choices). Detection efficiency and energy resolution remained largely stable, with notable deviations primarily linked to the parameter reset error. These findings demonstrate the instrument’s general robustness while highlighting specific anomalies and underscoring the need for ongoing monitoring, optimized operational protocols (especially HV management), and time-dependent calibration to ensure the highest data quality for solar flare science.