Abstract: An optical head for attachment to an optical system, such as a telescope, is shown. The optical head in a housing includes a first sensor for imaging an object in a field of view and a second sensor for tracking a star or other celestial body which is off axis to the field of view of the first sensor. The second sensor is rigidly supported and positioned a selected distance from and adjacent to the first sensor and is adapted to generate correction signals which are used to control a drive system of the optical system or telescope. The correction signals are representative of desired changes in the relative position of the optical system or telescope to the star being tracked. The correction signals are applied to the drive system to maintain, during imaging, optical alignment of the first sensor with an object in the field of view. In the preferred embodiment, the optical head is used for astronomical imaging and tracking wherein the first sensor is an imaging CCD and the second sensor is a tracking CCD.

Abstract: An optical image (54) of an astronomical scene is focussed by a telescope (16) onto a charge-coupled-device (CCD) photosensor array (50) to produce successive electronic pixel images (92) of the scene which are registered and co-added to produce an accumulated image (96) which is substantially free of streaking caused by rotation of the earth. A current image (92) is registered with an accumulated image (94) by sensing the coordinates of a selected bright star (90) in both images (92,94), computing the offset .DELTA.I between the coordinates, and shifting the current image (92) by the offset .DELTA.I prior to addition to the accumulated image. The telescope (16) may have a clock drive (24) to which the offset .DELTA.I is also applied to correct for mechanical tracking errors.