Hello
I'd like to up vote the Ihoujin's suggestionspecially if I consider elakrab's two remarks:
Almost all descriptions of the drift alignment methods I saw so far, misquote Scheiner's original description. That does not mean, that the procedure does not converge, but for sure not on the (refracted) celestial pole.
These alternative alignment procedures have been already described, e.g. in E. S. King's comprehensive paper
Forms of images in stellar photography
or in a more modern form by Toshimi Taki
Matrix Method for Coordinates Transformation
. Unfortunately I did not find his web site anymore. Toshimi Taki included calculated examples which may serve as test cases.
Implementing E.S. King's result, here shown as velocity in both directions,
should not be difficult.
My reasons to up vote this topic are
- these methods are differential
- can be carried out all over the sky
- if these corrections, position of the polar axis and refraction, are applied to INDI's JNOW coordinates, they can serve as a first order "pointing model" (without measuring several tens star positions). This could be done already with Ekos' results.
The last point implies, that the measured deviations from (refracted) CP are used to calculate the apparent position. Or saying that in other words, one can omit adjusting the polar axis in cases where only pointing is an issue. E.S. King described in his paper as well how to deal with various deficiencies of a mount itself. If one is interested in accurate tracking, eventually even dropping guiding, E.S. King's paper is an excellent starting point, as he showed it with his 1 hour unguided photograph of M13.
I add another wish. E.g. the telescope simulator driver should then include the mount's altitude and azimuth knobs. These are two writeable variables, where the position of the polar axis can be stored/adjusted.
Kind regards, wildi
P.S. Although I know what to do, I can not start coding right now.