Re: Dec Arc APPM mode: any l best practices for field set up

Ray Gralak

Hi Max,

My guess is that there weren't enough points in each dec arc row near where you were trying to image. There should be at least 5 points, but more is better. A good rule of thumb is to use a 5-degree (or less) spacing for both RA and Dec to get a nice sky grid.


-----Original Message-----
From: [] On Behalf Of Max Mirot via
Sent: Saturday, October 9, 2021 4:15 PM
Subject: Re: [ap-gto] Dec Arc APPM mode: any l best practices for field set up

I am getting poor results so far with the Dec arc tracking model on my AP1100 and AP Honders 305 combo.

First I made an all sky tracking model using 250 points.
I checked the Dec arc box and did 10 minutes.
The Image showed big ovals nearly short trails.
The standard model was nearly round at 10 minutes in the same area.

Next night I acquired new images with APPM. This was a single 15 point arc at the Dec only.
I got trailing across the entire image at 10 minutes.

APPM mapped a point near zenith in addition to the Dec arc.
I removed the zenith point from the calculation and model improved to long ovals again.

I tell ya , I get no respect. No respect at all ...


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