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7.7 Coudé Image Rotator

An image rotator/derotator is available by turning the hand-crank until it reaches its stop. Power to the rotator is provided through the switches on the slit-head panel for slew and track.

The image rotator, having been built originally for the 2.1 m telescope, will not work without manual intervention for the feed telescope. This is due to the feed's alt-az mount which results in non-uniform rotation of the field. Programs are available to calculate the required angle so that the rotator can be manually adjusted every few minutes to keep the slit projected to a particular angle on the sky.