Pre-flight calibration of the optics assembly for CATCH’s first pathfinder

• Published in: Experimental astronomy Vol. 59; no. 3
• Main Authors: Xiao, Jingyu, Huang, Yiming, Zhao, Zijian, Wang, Yusa, Yin, Qian-Qing, Zhang, Chen, Hou, Dongjie, Zhu, Yuxuan, Zhang, Yifan, Zhao, Donghua, Yang, Sheng, Men, Lingling, Jin, Ge, Tao, Lian, Zhang, Shuang-Nan, Chen, Wen, Dai, Yanfeng, Gao, Min, He, Huilin, Huang, Guoli, Li, Zhengwei, Liu, Xiaojing, Li, Panping, Li, Yajun, Ma, Ruican, Qi, Liqiang, Wen, Xiangyang, Xiong, Shaolin, Xu, Yibo, Xiong, Liyuan, Yang, Yong, Zhang, Juan, Zhang, Aimei, Zhou, Heng, Zhao, Shujie, Zhao, Kang, Zhao, Qingchang
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.06.2025; Springer Nature B.V
• Subjects: Angular resolution; Astronomy; Calibration; Chemistry and Earth Sciences; Computer Science; Field of view; Geometrical optics; Mechanical tests; Observations and Techniques; Physics; Physics and Astronomy; Point spread functions; Statistics for Engineering; Test facilities; X ray optics; X ray sources; X-rays; On-ground calibration; Effective area; CATCH-1; X-ray optics
• DOI: 10.1007/s10686-025-10001-3
• ISSN: 0922-6435

The first pathfinder of the CATCH mission, CATCH-1, was launched in June 2024. It is equipped with a light-weight, narrow-field optimized Lobster Eye X-ray Optics. By sacrificing a portion of the field of view to achieve a large effective area, the telescope’s sensitivity is enhanced. This paper presents the equipment and procedures employed for calibrating the optics assembly. A comprehensive on-ground calibration for the Lobster Eye X-ray Optics is conducted before its launch using multi-target X-ray sources and the pnCCD Color X-Ray Camera in the 100 m X-Ray Test Facility. The results are derived from calibration measurements taken before and after the mechanical testing and mainly include measurements of the focal length, point spread function, angular resolution, and the effective area for incident X-rays at 0.28 keV, 0.93 keV, 1.49 keV, 2.98 keV, and 4.51 keV. The results indicate that the mirror’s performance remains stable and no observable variation before and after the mechanical testing. At 0.93 keV, the mirror’s angular resolution is 6 . 11 ′ (FWHM), and the effective area is 40.75  cm 2 , meeting the expected performance of CATCH-1 X-ray optics.