ROTATOR ACCURACY/REPEATABILITY

1) Find a field with a relatively large number of stars--the outskirts of 
globular clusters or open clusters are good choices, or random spots in the 
Milky Way (especially the summer Milky Way) can work. Really any field with 
5 or more stars will work fine.

[Try using M38, around RA 05h 28m 35s, Dec. +35 48' 20" (J2000).]

2) Place the rotator in PA mode, near the minimum value achievable at that 
field. Choose and center one of the stars.

3) Take 3 images.

4) Rotate by 30 degrees, center the same star, and take 3 more images.

5) Repeat step 4 until the maximum rotator p.a. is reached.

6) Step back from the maximum p.a. to the minimum p.a. in 30 degree steps 
again, taking 3 full-frame images at each position.

Options:

This test can be speeded up by using only one frame per rotator angle.  However,
to test repeatability and measurement error it is recommended that at at least
one rotator p.a. 3 or more images be taken.

In step 4, you may choose not to recenter the star each time, if the star
does not seem to drift from image to image.