Hintze Centre for Astrophysical Surveys

Abstract:

A system to measure image size and motion has been designed, constructed and put into operation at the 4-meter Mayall telescope at Kitt Peak National Observatory (KPNO). The present system configuration consists of three elements. A 128 multiplied by 128 pixel CID camera is mounted at the south port of the Cassegrain instrument rotator. The CID camera is fed, under software control, by a movable mirror in the instrument rotator. Focusing is achieved by determining the point of zero-image motion when the f/8 beam is cut by a rotating Newall mask. Focal plane images are digitized and stored on digital disk for later determination of image size and motion as a function of time. The second element is a two-dimensional position sensor which records image motion induced along an air path located between the primary and secondary mirrors of the telescope. The third element monitors temperature of the telescope and air throughout the telescope structure. The system is described and preliminary results are presented.