Check the orientation of the camera, before you take a drift scan image
If the camera is in the right orientation, a star moves, at
shut of telescope drive, form the bottom(east) to the top(west) of
the image (from one standard image to the next).
To adjust the
orientation exact, take a standard image with the trails of the stars
(Turn off the clock drive of the telescope).Use an exposure time, a
little shorter than the time a star needs to move from the bottom to
the top of the image, so the ends of the trails are visible.(about 60
sec) A trail of a star should be exact at one column. (You can use a
program like CCDOPS and check that using the X-Hairs). If necessary
rotate the camera carefully.
As the orientation of the camera should
be more exact than 0.1 deg (ST-7) or 0.05 (ST-8), it will be necessary
to build an attachment for the camera, which enables you to rotate the
camera exactly.