The matter I was addressing was that I don't see that APPM's sky model has improved my guiding. Maybe it has, but it's not very visible in the numbers I see as the corrections roll by.
My guiding with the 17" astrograph can vary enormously depending on seeing. I've had guiding values of less than 0.1 arc sec RMS and as much as 0.5 RMS on a different night. Star sizes vary from 0.9 arc sec FWHM on the very best night to 3.5 arc sec FWHM on the worst nights. And none of this has anything to do with the sky model.
From: calypte@... [ap-gto]
Sent: Sat, Nov 4, 2017 11:51 pm
Subject: Re: [ap-gto] APPM error
The second question, about "custom tracking": yes, it's turned on in APCC. I had to go out to the observatory to see what you were talking about. I'm using MaxIm DL 6.xx for guiding. The matter I was addressing was that I don't see that APPM's sky model has improved my guiding. Maybe it has, but it's not very visible in the numbers I see as the corrections roll by. But I think this exchange has established that there's probably not much more I should expect from APPM's sky model.
The reason I've pursued this discussion more than once, as this topic recycles every few months in this forum, is due to what I see at Palomar Observatory, where I work as a volunteer. There's a sky model in the software for the 200-inch Hale Telescope. I think the model software was developed by a Caltech programmer. I don't think it's one of the commercial products (e.g. T-Point or Pin point). I don't know what they did to establish the points of the model. I've met the man who wrote it (I think), but I've never had a chance to discuss this software with him. The pointing accuracy of the 200-inch is far beyond anything I see with my own gear. Cassegrain is the most commonly used focus, f/16 or about 80m FL. The telescope weighs 530 tons. Yet, this colossal telescope, built when a computer was a slide-rule and a no.2 pencil, is able to put a star on the slit of a spectrograph nearly every time it executes a go-to. I've seen it. It's mind-blowing.