Study on the Motion Characteristics of Slant-axis Astronomical Telescopes

Due to its unique rotation mechanism, a slant-axis mount provides a better adaptability for the extreme site conditions, such as those in Antarctica, compared to traditional equatorial and altazimuth mounts. However, the study devoted to the motion characteristics of slant-axis mount has not been reported yet. In this paper, the advantages and disadvantages of the slant-axis mount are first discussed. The transformation relations between the slant-axis coordinate system and the horizontal and equatorial coordinate systems are then derived, based on this the motion characteristics of slant-axis mount during a normal sidereal tracking are studied, and compared with those of altazimuth mounts. The image rotation behavior of slant-axis mount is also studied, and its influence on the reflector holographic measurement is analyzed. Finally, a pointing model including seven error terms and suitable for slant-axis telescopes is derived.