For #astrophotography, one of the things you have to worry about is making sure the telescope stays locked on the target as accurately as possible because if it drifts at all, it'll ruin the long exposure images you need. Stars will be egg-shaped (or squiggly streaks if your rig really sucks lol)
This is done with a smaller secondary camera and scope (guidescope), that can be used by the appropriate software to adjust the mount by using the star position as a feedback loop (autoguiding).
/1