Precision control and on-orbit verification of optical structure of the FXT onboard the EP satellite Precision control and on-orbit verification of optical structure

• Published in: Radiation detection technology and methods Vol. 9; no. 2; pp. 283 - 292
• Main Authors: Wang, Juan, Zhao, Xiaofan, Yang, Xiongtao, Zhao, Zijian, Yang, Yanji, Duan, Xuliang, Qin, Genjian, Wu, Hao, Eder, Josef, Cui, Weiwei, Ma, Jia, Wang, Hao, Zhu, Yuxuan, Liu, Huaqiu, Han, Dawei, Wang, Yusa, Chen, Yong
• Format: Journal Article
• Language: English
• Published: Singapore Springer Nature Singapore 01.06.2025
• Subjects: Beam Physics; Hadrons; Heavy Ions; Nuclear Energy; Nuclear Physics; Original Paper; Particle Acceleration and Detection; Physics; Physics and Astronomy; FXT; Optical structure; EP; Precision control; Wolter-I
• ISSN: 2509-9930; 2509-9949
• DOI: 10.1007/s41605-025-00545-5

Purpose The Einstein Probe (EP) satellite is a space X-ray satellite for time-domain astronomy and high-energy astrophysics. The precision control of the optical structure directly affects the imaging quality and positioning accuracy of the Follow-up X-ray Telescope (FXT), playing a crucial role in achieving the on-orbit scientific objectives of the FXT. Higher positioning accuracy makes it easier to identify corresponding bodies for the discovery and positioning of transient sources. Accurate positioning is beneficial for follow-up observations in other bands, such as optical spectroscopy. Methods This article mainly introduces the precision control methods and processes of the FXT optical structure, which have been tested and verified through satellite test. The on-orbit source positioning accuracy of the FXT telescope is within 20 arcseconds (90% confidence level), meeting the requirements of the FXT mission. Results and Conclusion To ensure the accuracy of the EP satellite’s FXT optical structure, measures such as component processing control, installation control, and posttest adjustments are taken on the ground to ensure that the detector mounting position, optical axis deviation, and other precision indicators before and after the satellite lever test meet the design requirements. After a successful launch, through on-orbit calibration, the FXT-A and FXT-B optical axis pointing direction deviation is 39 arcseconds, and the source positioning error is better than 3 ′ ′ at 68% confidence level. FXT optical structure meets all the requirements from design, processing, installation, etc., successfully meeting scientific needs.