In case anyone is interested, I found some hints
in this post
from @hy.
A more complete documentation of the meaning of these terms can be found in
this article from Patrick Wallace
.
The INDI simulator tab includes the following terms to define the mount model:
I have transcribed Table I from Wallace which describes the six geometric terms for an equatorial mount:
Where h is hour angle and δ is declination
Extracted from the article:
- IH and ID : zero-point corrections to the hour angle and declination readouts.
- CH: Describes how accurately the telescope optics are aligned within the tube, whether the tube is at right-angles to the declination axis and any east-west displacement of the crosswires, the center of the CCD, or whatever other aiming-point is being used.
- NP: The declination axis is supposed to be at right-angles to the polar axis; NP describes any deviation from this condition.
- MA and ME: describe how far the polar axis is from the true pole, up-down (ME) and left-right (MA).
In the above tables, each of the coefficients is a small angle, usually expressed in arcseconds.
The formulas for Δh and Δδ give the corrections to be added to the telescope readouts.
The set of coefficient values and the formulas constitute the telescope's pointing model...
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