The optical sensors of the Netherlands astronomical satellite (ANS). III. The star sensor.

The star sensor is mounted behind the telescope which is to be used in the UV-spectroscopic studies to be conducted. The star sensor supplies the onboard computer with accurate information for the pointing of the telescope. A reference direction is obtained with the aid of two relatively bright guide stars in the neighborhood of the object to be studied. Questions of device construction and operation are discussed along with the search for the recognition star, the tracking process, and prototype tests.