The influence of panel gaps on the system noise temperature of the FAST

A Five-hundred-meter Aperture Spherical Telescope (FAST), the largest singl e dish in the world, is proposed to be built in one of the karst depression s in Guizhou province. The main spherical reflector is to consist of about two thousand small panels, which can be adjusted to fit a paraboloid in rea l time. There are many slit-like gaps across the aperture due to manufactur ing error, thermal effects and deviations between a sphere and a paraboloid . The influence of the energy leakage of the narrow gaps on the system nois e temperature of the FAST reflector is discussed in this paper.