How accurate is my Advanced Series GT mount's alignment?
November 12, 2008
Go to Scope Setup> Mount Settings to find out. Cone Value gives the cone error found once calibration stars were added to the alignment. It should be less than ½-degree. You may need to shim between the OTA and the dovetail plate if it exceeds this value. A dime or other thin metal piece can be used.
Go to Utilities > Polar Align > Display Align to get the accuracy of the polar alignment in both altitude and azimuth. For a good alignment, it should be at the arc-minute level. Alternatively, use Get RA-Dec under the main menu to assess the accuracy of the position when looking at a star or object with known coordinates.