Control and pointing challenges of antennas and telescopes

Extremely large telescopes are constructed and new radiotelescopes operates at significantly higher radio frequencies; both features create significantly increased pointing accuracy requirements that have to be addressed by control system engineers. The paper presents control and pointing problems encountered during design, testing, and operation of antennas, radiotelescopes, and optical telescopes. This collection of challenges informs of their current status, helps to evaluate their importance, and is a basis for discussion on the ways of improvement of antenna pointing accuracy.