Measurement scheme and simulation for the main reflector of FAST

FAST (five-hundred-meter aperture spherical radio telescope) is a radio telescope being built in a karst depression in Guizhou Province of China, which will be the largest single dish radio telescope in the world [1]. The reflector of the telescope is composed of over 4000 panels, and each panel could adjust its position according to observation requirements. During observations, panels in the illuminated area could form a paraboloid to correct spherical aberration [2]. Therefore, accurate measurement of the positions of panels is crucial for the operation of the telescope. In this paper, we introduce the measurement scheme for the reflector of FAST, and simulate its accuracy using direct linear transform, Gauss–Newton algorithm, Levenberg–Marquardt algorithm and an algorithm referred to as multi-point algorithm. Advantages and disadvantages of using these four methods are compared for analysis at different locations of the panels on the reflector, and suggestions are given in choosing algorithms in implementation. (paper)