NOVA 120 Pointing model user manual
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1. Introduction
A Pointing model is supported by the NOVA mounts family. It is essential to achieve it properly to create the best from
your mount. Pointing model improves pointing accuracy, but also mount tracking accuracy, because the mount software
can use the pointing model to get a speed model and also compensate for mount polar alignment errors, or any other
errors that are supported by the model.
Left is an image with no pointing model, where the user tried to center the right star (field of view is 15x15 arcmin) but
no star is present. Right is an image that demonstrates the effect of the pointing model: the star is at the image’s center.
Working without a pointing model can allow dramatic errors with a German mount. Meridian flip and optical axis non
perpendicularity error with the DEC axis can lead to pointing errors more than ½ of a degree! This causes most of the
time, the target to be outside the field of view of the camera. A Pointing model can overcome this easily, allowing better
use of your telescope, and not wasting time acquiring your target.
The next picture shows what happens with a poorly polar mount alignment (18 arcmin error from the pole) and a 600s
unguided exposure.
