Measuring Track-Related Pointing Errors on the Nanshan Radio Telescope with an Optical Pointing Telescope

Figure 1

The difference in twist between top and bottom positions of the alidade according to the track-alidade model. The ideal and twisted states of the alidade are depicted in black and red colors, respectively. The dashed lines at the top denote the elevation axis, while the arrow vertically above the axis indicates the pointing direction of the instruments above the elevation axis. The arrow at the alidade’s bottom indicates the measuring direction of the OPT.