Re: Autoguiding questions
Ray Gralak \(Groups\) <groups2@...>
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The problem with project like that is that it can take many minutes to determine periodic error and drift (then if the user slews to another target the process has to start all over). Having looked at literally thousands of periodic error curves the atmospheric seeing conditions and other factors can drastically distort periodic error and drift, making an automatic auto-guiding process very difficult.
Author of Astro-Physics Command Center (APCC)
Author of PEMPro: http://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: http://www.gralak.com/apdriver
Author of PulseGuide: http://www.pulseguide.com
Author of Sigma: http://www.gralak.com/sigma
From: ap-gto@... [mailto:ap-gto@...]
Sent: Wednesday, December 17, 2014 8:36 PM
Subject: Re: [ap-gto] Re: Autoguiding questions
>> I have often thought that a better slow guiding system would measure the average drift of the axes
>> over a period of 10 - 20 seconds
Actually, PHD2 has it already. If you choose "Lowpass" as the guide algorithm, it will look at the drift trend and apply corrections based on that. The "slope weight" parameter is an aggressiveness setting. It's most applicable to use this algorithm for the Dec axis, though I have heard of people using it for RA.
Taking the idea a big step further, there is a project in the works from a research group at the Max Planck Institute for Intelligent Systems in Tubingen, Germany to make predictive corrections accounting for both drift and PE. The work is currently being integrated into PHD2, though it is not yet included in the released versions. There is some discussion of the project in the PHD2 google group if you are interested in more details, like a link to the research paper.