The RBC port is equipped with an optical offset facility guider. The guider optical path consists of a fold mirror, a field lens, and a reimaging lens.

This is a schematics of the relative position of the RBC offset guider with respect to the FOV of the slit viewing camera and the NIRES slit. The slit is shown in red. The actual guider FOV is inscribed within the fold mirror footprint.


The camera includes a Tiffen red 25 filter.

Filter curve

Camera and Detector

The camera is a Photometrics Series 300:77B CCD camera with a thermoelectrically cooled CH350 camera head. The main parameters are as follows.

array size pixel size
plate scale
[arcsec per pixel]
Field of View
512x512 24 0.22 1.8x1.8

Guider image example

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