Adding Extra Data - How do you get near the position of the orig. frames?

[jcm]

Ok , did not give a very good subject line.

What I mean is , lets say you take 1 hours worth of H-alpha data and the clouds roll in. You think no matter , I will just add the OIII data at a later date. How do people get the new frames with the same alignment as the older ones.

They way I did it , was to load an original image into say AstroArt ( or similar) use the cursor on an obvious bright star and note the X/Y position in pixels. Then start the new imaging and keep adjusting the telescope position with the hand controller until the new images have the star in the same X/Y position.

Are there any other better methods?

John