Ground testing and calibration of focal plane detector flight model on board the first pathfinder of CATCH

CATCH-1, as the first satellite of Chasing All Transients Constellation Hunters (CATCH) space mission, was successfully launched into its expected orbit on June 22, 2024. The flight model underwent environmental tests before launch, including thermal cycling, thermal vacuum, and mechanical evaluations. The CATCH-1 detector system is equipped with a 4-pixel Silicon Drift Detector (SDD) array. To ensure the reliability and redundancy of the CATCH-1 detector system, two sets of data acquisition systems were independently designed and calibrated. Our focus is on presenting the ground calibration results of CATCH-1, which demonstrate a strong linear correlation between energy and channel. The main data acquisition system achieves an energy resolution of \(\sim \) 120 eV@4 keV, while the backup data acquisition system has a slightly lower energy resolution of around 150 eV@4 keV, both meeting the design requirement of \(\le \) 160 eV@4 keV. Additionally, the time resolution is \( \sim 4\,\mu s\), complying with the design requirement of \(\le 10\,\mu s\). The calibration database now includes the ground calibration results of CATCH-1, establishing a dependable basis for future data analysis. The development experience, calibration, and test results of this detector system will also provide a solid foundation for subsequent tasks such as CATCH-2.