The drive motors are controlled via a PC running software supplied by Comsoft. The dome position is encoded, and when properly set will follow the motion of the telescope. An autoguider program running on a PC allows movement of the TV pickoff mirror, in the Top Box, focus of the TV, as well as autoguiding. The TV field is presently about 2 arcminutes. The Top Box also has an 8 position filter wheel, which is controlled by the Sun computer.
Filters are changeable only by qualified people.
For IR observing, this filter wheel is disabled, and one filter is removed to allow light to reach the IR camera. Cooling is provided by a refrigerator which runs at full power all the time. The refrigerator has two stages. The first reaches a temperature of about 75 K, with the help of some liquid nitrogen, and is used to cool the shield. The second stage reaches about 10 K and is used to cool the detector.