Simulation studies for the first pathfinder of the CATCH space mission

• Published in: Experimental astronomy Vol. 57; no. 1
• Main Authors: Huang, Yiming, Zhang, Juan, Tao, Lian, Li, Zhengwei, Zhao, Donghua, Yin, Qian-Qing, Wen, Xiangyang, Xiao, Jingyu, Zhang, Chen, Zhang, Shuang-Nan, Xiong, Shaolin, Bu, Qingcui, Cang, Jirong, Cao, Dezhi, Chen, Wen, Ding, Siran, Gao, Min, Gao, Yang, Hou, Shujin, Jia, Liping, Jin, Ge, Li, Dalin, Li, Jinsong, Li, Panping, Li, Yajun, Liu, Xiaojing, Ma, Ruican, Pan, Xingyu, Qi, Liqiang, Rao, Jinhui, Sun, Xianfei, Tang, Qingwen, Tang, Ruijing, Wang, Yusa, Xu, Yibo, Yang, Sheng, Yang, Yanji, Yang, Yong, Zhang, Xuan, Zhang, Yueting, Zhou, Heng, Zhao, Kang, Zhao, Qingchang, Zhao, Shujie, Zhao, Zijian
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.02.2024; Springer Nature B.V
• Subjects: Astronomy; Charged particles; Chemistry and Earth Sciences; Computer Science; Cosmic x rays; Energy bands; Magnetic equator; Microsatellites; Observations and Techniques; Physics; Physics and Astronomy; Satellite constellations; Sensitivity; Sensors; Simulation; Space missions; Statistics for Engineering; X-rays; X-ray telescope; Geant4 simulation; Sensitivity; Effective area; Background; CATCH
• ISSN: 0922-6435; 1572-9508
• DOI: 10.1007/s10686-024-09924-0

The Chasing All Transients Constellation Hunters (CATCH) space mission is an intelligent constellation consisting of 126 micro-satellites in three types (A, B, and C), designed for X-ray observation with the objective of studying the dynamic universe. Currently, we are actively developing the first Pathfinder (CATCH-1) for the CATCH mission, specifically for type-A satellites. CATCH-1 is equipped with Micro Pore Optics (MPO) and a 4-pixel Silicon Drift Detector (SDD) array. To assess its scientific performance, including the effective area of the optical system, on-orbit background, and telescope sensitivity, we employ the Monte Carlo software Geant4 for simulation in this study. The MPO optics exhibit an effective area of 41 cm 2 at the focal spot for 1 keV X-rays, while the entire telescope system achieves an effective area of 29 cm 2 at 1 keV when taking into account the SDD detector’s detection efficiency. The primary contribution to the background is found to be from the Cosmic X-ray Background. Assuming a 625 km orbit with an inclination of 29 ∘ , the total background for CATCH-1 is estimated to be 8.13 × 10 - 2  counts s - 1 in the energy range of 0.5–4 keV. Based on the background within the central detector and assuming a Crab-like source spectrum, the estimated ideal sensitivity could achieve 1.9 × 10 - 12  erg cm - 2  s - 1 for an exposure of 10 4  s in the energy band of 0.5–4 keV. Furthermore, after simulating the background caused by low-energy charged particles near the geomagnetic equator, we have determined that there is no need to install a magnetic deflector.