GEM Geometry ???s
Posted 31 January 2010 - 05:05 PM
Posted 31 January 2010 - 07:31 PM
Posted 31 January 2010 - 08:29 PM
The confusion you are having is probably around cone error. Cone error will manifest itself as a POINTING error. If the mount has cone error, when you align the mount and do an alignment on either the or west side of the mount, if there is cone error, the indexes will only be accurate for that side of the mount (east or west). If you are using setting circles or if you are using a Go-To scope, when you slew the telescope to the opposite side of the mount and use the setting circles (or the Go-To), the cone error will result in the scope slighthly missing the target.
The early Go-to scopes and digital setting circles did not have any method for compensating for this error, so the telescope had to be shimmed to bring the optical axis into alignment with the RA axis.
Otherwise, even with cone error, once the scope is polar aligned an a target is in the eyepiece, it will not drift from the field. You might have trouble FINDING the object though. lol.
Posted 31 January 2010 - 10:15 PM