This is a collection of known issues and problems with INGRID at WHT. All observers should be aware of these when observing with INGRID and / or reducing the data.
 

• MODERATE: When changing filters and pupil wheels, please make sure that you move the pupil wheel last. The three wheels containing the filters and pupils are mounted on the same rotational shaft, and very slightly influence each others position if moved. Thus, the pupil stop has to be brought into the beam at the end in order to ensure a proper background.