An image rotator is installed in HIRES that is located immediately after the instrument hatch. The rotator allows for setting a specific position angle (measured in degrees east of north) or for observing in vertical angle mode (i.e. aligned with parallactic angle). The rotator gui can be brought up by clicking on the "R" in XHIRES just below the rotator icon. To change the mode of observation, click on the relevant button in the rotator gui, i.e. vertical, position angle, physical, and set the desired angle. The rotator can also be moved out of beam completely if desired."