Also note the importance of image scale for astrometry, so match your telescope to CCD pixel size. Astrometry typically requires high accuracy/precision. This does not mean that your image scale must match this, but you should work around the 2" arcsec per pixel margin.
Here are some good starting point references;
http://cfa-www.harvard.edu/iau/info/...etry.html#sort
http://cfa-www.harvard.edu/~tspahr/astrom.howto
http://www.nofs.navy.mil/data/FchPix/ - catalog searches - you'll need this.
Something that can really assist in research work is a CCD camera that is capable of Time-Delay Integration (TDI).
TDI is an imaging technique in which rows of pixels are synchronized and transferred at the same motion and rate as the scene.
"Basically, one points the camera at an area of sky and turns off the telescope drive to let the stars drift across the field of view. The CCD is clocked in sync with the rate of drift and the resulting image has an exposure time equal to the amount of time it takes the stars to drift across the CCD. Depending on the focal length of the scope this can be many minutes. But there is no periodic error and no guiding error." from the optcorp site.
With TDI, the important factor here is that you're astrometry precision is no longer limited by your telescope mount tracking. The telescope simply points and does not track. So there is the potential to make sub 1" arcsecond measurement if the atmospheric seeing is stable.
Thought I'd also add that TDI is what camera manufactures generally call what we know as drift scan imaging. Its has multiple uses, but Astrometry is a key one.