#### Re: APPM data meaning

Ray Gralak

Hi Sam,

Thank you for the explanation Ray - it is understood that each scope / mount setup is unique and may be
affected by a number of factors in different ways, so it is good to know that the model tries to account for
these variables through a curve-fit approach and shows the results for each of these variables in the model
(left of screen)
The all-sky model does not use a curve-fit approach. To do that it would have to know the type of curve being fitted, which can be quite complex and vary between setups. It uses another mathematical approach.

If the above is incorrect, how would one get a measure of « repeatability ».
The best way is an empirical approach in APPM by using the "Model 5x and Park" option in the "After Complete" dropdown list. This will perform five mapping runs in a row, and from that you can compare the errors between the runs. If the setup is solid, the RA/Dec pointing error for each run will be similar.

-Ray

-----Original Message-----
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Sam
Sent: Wednesday, January 26, 2022 6:50 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] APPM data meaning

Thank you for the explanation Ray - it is understood that each scope / mount setup is unique and may be
affected by a number of factors in different ways, so it is good to know that the model tries to account for
these variables through a curve-fit approach and shows the results for each of these variables in the model
(left of screen)

I have a question regarding your comment « A more important factor is repeatability« .

Am I correct to understand that the model « bulls eye » charts provide an indication of error and repeatability ?
(Since a large number of platesolves are done within close proximity).
For instance the charts I got show an avg error of 8 seconds and a range of 20 sec - are these in the right
ballpark or should they be better ?

If the above is incorrect, how would one get a measure of « repeatability ».

thanks
sam

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