Baseline measurement for Chinese spectral radioheliograph

The Chinese Spectral Radioheliograph (CSRH) is a solar-dedicated synthesis aperture telescope. The maximum baseline length determines the high resolution of synthetic aperture. With its antenna array aligned in a shape of triple-spiral arms spread in an area of about 10 square kilometers. The measurement precision of CSRH tri-spiral antenna array baseline is one of the key factors for CSRH image quality. In this paper, the method of geodetic surveying and astronomical interferometry used to obtain the 3D coordinates of different antennas is introduced. The results will be verified by observing the radio source [1-3].