I disagree Ray that this is the more likely reason. If it were the reason then I would see a divergence between
ATrack and APCC. I don't, they follow each other in parallel which means there is a constant factor that is causing
the difference. The two likely constants are: a) the sidereal rate is not sidereal, or b) the encoder, if used to
determine sidereal rate, is not calibrated.

That doesn't prove anything. That coincidence could be accounted for by many things, including different refraction calculations.

I am certain that the version of APCC you are using doesn't account for changes in modeling parameters because of temperature.

-Ray Gralak
Author of APCC (Astro-Physics Command Center): https://www.astro-physics.com/apcc-pro
Author of PEMPro V3: https://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: https://www.siriusimaging.com/apdriver

-----Original Message-----
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Craig Young
Sent: Tuesday, May 5, 2020 5:34 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Adjust CP4 Clock Frequency

I disagree Ray that this is the more likely reason. If it were the reason then I would see a divergence between
ATrack and APCC. I don't, they follow each other in parallel which means there is a constant factor that is causing
the difference. The two likely constants are: a) the sidereal rate is not sidereal, or b) the encoder, if used to
determine sidereal rate, is not calibrated.

Craig