Re: APPM data meaning

Luca Marinelli

Hi Ray,

I think the naming of the correction terms is self-explanatory. What may be confusing are the units. Are the correction terms expressed in arcsec or different units?



On Jan 25, 2022, at 10:01 AM, Ray Gralak via <iogroups@...> wrote:

´╗┐Hi Sam,

The pointing terms are the best-fit values for various mechanical factors. I said "best-fit" because they may or may not accurately represent the mechanical factor. So, trying to put a detailed reason for each term may lead someone to believe that something needs fixing when there isn't. The model is there to compensate for those factors. A more important factor is repeatability. For example, if there is a lot of randomness in pointing because something moving around (e.g. a primary mirror in a large scope) then the model will not be as effective.

The only exception may be the polar alignment terms, which depending on their magnitude, may introduce field rotation.


-----Original Message-----
From: [] On Behalf Of Sam
Sent: Tuesday, January 25, 2022 6:11 AM
Subject: Re: [ap-gto] APPM data meaning

Hi Andrew,

Yes exactly - the checked boxes correspond to a variable which has been solved by APPM and is specific
type the mount / scope configuration.
There is limited information in the APCC help files (as per my earlier email).
However, most users will surely want to better understand the data (I.e. what does the variable mean, what is
a normal range etc.) so adding more complete descriptions would be useful.


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