On Sun, 11 Apr 2004 17:26:07 GMT, "Antonio Zanardo"
wrote:

No, the sole condition to obtain a perfect tracking without any field
rotation is the RA axis pointing to true North, regardless on how you
obtained that.
However, if your scope is mounted on a wedge, you'll be able to measure the
*true* altitude and/or azimut angle of a star only if the plate is
*perfectly* leveled.and, of course, axes true squared.

Do you mean you'll only be able to measure the true altitude of the polar axis
using some sort of scale? You certainly can measure the true altitude and
azimuth of any star once the scope is polar aligned, regardless of whether the
wedge is leveled and squared. Also, it is worth noting that the standard
procedures for aligning an equatorial mount do not require that the true
altitude or azimuth be measured (indeed, there is no practical instrumentation
available to measure either of these angles with the precision necessary for
good polar alignment).

Both alignment by the drift method, and by the modeling method, require only
relative movements of the altitude and azimuth adjustments of the mount.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com