Pier footing complete

Dome center of curvature
The shutter motor is not shown in the model, but it extends about 30 cm from a point near the dome's zenith. By lowering the mount about 20 cm, the telecope will miss the shutter motor by five cm.

A four meter dome provides little space for a 62 cm telescope with an f3.4 primary and accessible prime focus. Had the prime focus not been accessible, then the optical tube assembly (OTA) would have been considerably shorter.

 

Danger of collision

As it is, the prime focus camera and filter wheel will collide with the shutter drive motor if the mount is located at the center of curvature of the dome. The rotational center of the mount is the intersection of the right ascension (RA) and declination (DEC) axes. This point is normally placed at the center of curvature of the dome, making the telecope's sphere of rotation concentric to the dome.

 

The base of the pier footing covers one square meter, and extends all the way down to crystalline basement rock, about 50 cm deep. The footing is anchored directly to the basement rock. Steel reinforcing bars drilled and cemented deep into the rock ensure a strong bond.

 

Small margin of error

The upper part of the pier footing is cast on top of this cube of concrete. Because of the small clearance between the telescope and dome, the dome had to be in place before the upper part of the pier footing could be cast. Therefore, the pier footing had to be cast in two operations in order to determine the exact height of the pier.