Software Bisque Paramount ME - Precise Polar Alignment; Polar Alignment Using TPoint

Paramount ME User’s Guide
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Note that the non-perpendicularity of the telescope and the declination axis also plays a
key factor in the quick alignment procedure. If this error is large, the initial polar
alignment will not be as accurate. (This error can exceed twenty arcminutes, and makes
this procedure less effective.)
Precise Polar Alignment
There are many different methods for achieving a precise polar alignment of a telescope
system. Unfortunately, many of the more novel approaches assume the telescope/mount
system is more or less perfect. Since numerous errors creep into every telescope system,
any method that relies on perfect perpendicularity is flawed. As described in the prior
section, the optical path is typically non-perpendicular to the declination axis so any
method that assumes perpendicularity will be in error.
The old reliable “drift method” does not make these assumptions, but can take hours to
complete.
Since an accurate polar alignment is required before the Paramount ME can accurately
track objects, the question is, “how accurate?” Subjectively, if the altitude and azimuth are
both within two arcminutes of the pole, images that are exposed for few minutes duration
can be acquired while maintaining round stars at focal lengths of 2000 mm or so. For the
given accuracy of polar alignment, at larger image scales and longer exposures,
autoguiding is required since adjustments in both altitude and azimuth are made. Polar
alignment becomes increasingly difficult to improve once an axis is within one arcminute
of the pole.
Polar Alignment Using TPoint
Once you have successfully performed a mapping session and developed a TPoint model,
you can use TPoint to determine the mount’s polar alignment. Use the values computed
by TPoint for the Polar Axis Elevation and Polar Axis azimuth (EW) to make the necessary
adjustments to the Paramount ME’s altitude and azimuth adjustments. Usually one or
two iterations can get each axis within two arcminutes.
Getting Started Using TPoint
Once you are familiar with the technique of telescope mapping as described in the TPoint
User’s Manual, you are ready to collect modeling data. If the Paramount ME’s polar
alignment is way off, even short star-hopping slews may require the destination star to be
re-centered in the eyepiece.