Described embodiments provide methods and apparatus for adjusting a line of sight to a target to compensate for drift. Embodiments can include an optical assembly configured and arranged for viewing an area including the target, a display window for viewing a line of sight to the target, one or more manual operator controls connected to a digital processor configured to adjust offsets to the line of sight, an automatic operating mode configured to automate adjusting the offsets to correct for drift bias of the line of sight to the target, and an operator control switch configured to switch the system between the automatic mode and a manual mode.