3.3 Acquisition and Guiding

SOFIA has three optical cameras for acquisition, guiding and tracking. The Wide Field Imager (WFI) and Fine Field Imager (FFI) are mounted on the telescope head ring. The upgraded Focal Plane Imager (FPI+) images the focal plane of the telescope via a dichroic and a tertiary mirror. All three imagers use ''High Speed Slow Scan'' CCD cameras.

The WFI has a 6°x6° field of view, and is expected to achieve a centroid precision of ~8'' for stars brighter than R = 9. The field of view of the FFI is 1°x1°. It is expected to achieve a centroid precision of ~1'' for R = 11 or brighter stars. The FPI+ has an 8' diameter and is expected to provide a centroid precision of 0.05'' for R = 16 or brighter stars.

Most observers do not need to select guide stars as they will be chosen by the SMO staff. However proposers should be aware that the guiding cannot be done on IR sources unless they are optically bright.

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