COMETS.
Techniques.
Imaging a comet uses the same techniques as used for deep-sky work. However, a comet moves against the stars so one should not guide on the stars but on the nucleus of the comet! This will produce startrails on the image but the comet will show more detail. Unless the comet is quite bright and has a good and bright point-like nucleus you could guide visually or autoguide with a ST-4 or STV on the comet, but in most cases this is not possible. A good solution is a programmable drive corrector. Using the comet elements and a program such as Megastar or The Sky, calculate the drift of the comet in Right Ascension and Declination during 24 hours. These data are then programmed into the drive controller and if everything is OK, the drive should track the comet instead of the stars....
Comet 1999T1 McNaught-Hartley.