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Tracking system of LAMOST telescope

The Large Sky Area Multiobject Fiber Spectroscopic Telescope (LAMOST) has an extraordinary structure, its spherical primary mirror MB is fixed. The optical axis from MA to MB is tilted 25 degree(s) from horizontal direction. This structure has the advantage of compact, light, low cost, it is similar to a horizontal Meridian Circle, but different in many structure details. The MA has the alt-azimuth mounting. While observing, MA should be rotating in altitude and azimuth direction to tracking the celestial objects, at the same time the focal plane should be rotating for certain angle. For observing different sky area the focal plane will tilt a small angle. When the temperature changes, the focal plane can focusing. This paper describes the preliminary design of the tracking system for LAMOST telescope. That include the Schmidt corrector MA system and focal plane system. For the MA system there are driving and supporting mechanism of altitude axis, diving and supporting mechanism of azimuth axis. For the focal plane system, there are five subsystems: base, frame, field rotator, focusing mechanism and tilting mechanism. The analyses for the tracking system are presented in this paper.