Re: APPM Models


Ray Gralak
 

Hi Kevin,

I ran my first successful model tonight of 30 points.
Obviously I am going to want to try a much larger model, but I
am wondering how long can I use it. I was thinking about a hundred or so.
If I go for 150 or 200 or so, can I use
that model for multiple days? A week?
If you don't change anything, the model will likely work pretty well indefinitely, but some things will hinder the model's accuracy.

First, to properly account for refraction, you should supply APCC with real-time Temperature, Pressure, and Humidity measurements. The MGBoxV2 is one of the devices capable of supplying this information. You can add this device, or any other ASCOM device with an ASCOM Observing Conditions driver, in APCC's Environmental Settings.

Some potential issues include:

1) Non-repeatable pointing. Some telescopes with non-fixed mirrors can introduce random pointing errors.
2) Any settling of the pier into the ground can change polar alignment.
3) Loose or flimsy mounting plates can introduce randomness.
4) An inadequate focuser can introduce extra flexure and/or introduce randomness.
5) Drastic changes to OTA flexure in temperature changes can subtly affect the pointing model.
6) Hanging cables can introduce randomness, especially if one gets caught on something.
7) Any changes to the setup after a model has been created will usually reduce the model's effectiveness.
8) Any inaccuracy in the plate solves will obviously affect accuracy.

Provided that there is not significant pointing randomness nor unmodeled setup characteristics, each hemisphere model's pointing and tracking rate accuracy will improve as the square root of the number of points. Pointing and tracking rate accuracy should not change significantly over time as long as the setup is stable, which means minimally that the following do not change: polar alignment, flexure, telescope setup, and the total weight of all equipment, counterweights, and balance.

That said, it's pretty easy to create a new model. APPM should be able to capture 2-3 points per minute, or 120-180 points per hour.

-Ray Gralak
Author of PEMPro
Author of APCC (Astro-Physics Command Center): https://www.astro-physics.com/apcc-pro
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 KHursh via groups.io
Sent: Friday, November 27, 2020 6:35 PM
To: main@ap-gto.groups.io
Subject: [ap-gto] APPM Models

I ran my first successful model tonight of 30 points. Obviously I am going to want to try a much larger model, but I
am wondering how long can I use it. I was thinking about a hundred or so. If I go for 150 or 200 or so, can I use
that model for multiple days? A week?

Kevin

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