next up previous contents
Next: Pointing Performance Up: THE ROSAT SPACECRAFT Previous: The AMCS

Star Sensors

Two CCD star sensors are available for position sensing of guide stars. The optical axes of the star sensors are tilted by tex2html_wrap_inline1844 with respect to the optical axis of the XRT. The field of view of each sensor is a rectangular area of tex2html_wrap_inline1846 with an overlap of about tex2html_wrap_inline1848 ; the overlap region of the two star sensors also overlaps with about half of the PSPC and HRI fields of view.

Bright objects must be avoided by the star sensors; this particularly applies to the Moon and the Sun-lit Earth's limb which - while in the field of view of the star sensors - prevent any position sensing by the star sensors.

Michael Arida
Tue Jun 11 16:18:41 EDT 1996