Re: Strange numbers in APPM model #APCC #Mach2GTO


Ray Gralak
 

Hi David,

some of the numbers I'm getting for the model parameters are many orders of magnitude different
than the usual values.
The all-sky model requires data in a larger area of the sky to accurately determine the pointing terms, so you cannot count on the all-sky pointing terms being accurate with just a few rows of declination arcs.

If you are in a permanent setup, the ideal way to get the advantages of declination arc tracking accuracy and all-sky modeling is to capture a lot of data points (400+) so that there are many declination arcs throughout the entire sky.

-Ray

-----Original Message-----
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of David Johnson
Sent: Thursday, September 2, 2021 6:10 PM
To: main@ap-gto.groups.io
Subject: [ap-gto] Strange numbers in APPM model #APCC #Mach2GTO

[Edited Message Follows]

I've been using the Dec Arc feature, and it seems to work well. Thank you for implementing it. However,
some of the numbers I'm getting for the model parameters are many orders of magnitude different than the
usual values. For example, I'm doing a model with two arcs, one at 61 degrees N declination and one at 63
degrees. Below you can see what it looks like. The resulting model numbers are also shown below. Notice
some of the "west" parameters.

The mount tracks well, so it's not a functional issue, but it puzzles me that the numbers are so different. Is
this caused by doing the two arcs close together and no points elsewehere? If so, would I have major issues
if I tried to do regular tracking correction away from the two arcs? I doubt I would do that, because I'm
obviously concentrating on a target between the two arc declinations, but I do sometimes change targets for
unforeseen reasons, and maybe if I do I should just turn tracking off if I don't want to do another model?




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