Re: Screen shot on a coooold night (Gonna shoot tonight - it's clear and BRRRRR)
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Well, my night started off with .6 RMS error as the temperature plunged after sunset. But after a few hours, and especially close to midnight, the seeing steadied up and the stars went from 4 arc sec blobs to 1.8 arc sec. That's typical of the wide open spaces of the Midwest when we are under a high pressure dome like what's happening right now. Clear sky Clock can tell you pretty well what your seeing is going to be, and that's basically what you have to work with. Poor seeing = poor guiding results.
I do 5 second exposures with 2 second delay between exposures. I'm also now using multi-star guiding, but even that does not guarantee good guiding if the seeing is bad. You can always judge your seeing by looking at the Dec axis guide star fluctuations with corrections turned off. Since Dec stands perfectly still and does zero tracking, any fluctuations are totally due to the atmosphere. That will be your baseline which you cannot get better. PHD has a guide assistant that shows all the details. It's really a powerful program. MaximDL by comparison is rather basic.
From: Terri Zittritsch <theresamarie11@...>
Sent: Sun, Feb 14, 2021 9:04 am
Subject: Re: [ap-gto] Screen shot on a coooold night (Gonna shoot tonight - it's clear and BRRRRR)
Hi Roland, I was running my mach2 down to -6 on Friday night without issue. And still getting 0.59", 0.24 pixel error. which is fine for my imaging scale. I use PHD2 and this is typical for me. I never see guiding graphs like you see, which makes me think that Maxim DL graphs something different than PHD2. My RMS error for RA was .37" (0.15 pix) and my DEC error was .45" (0.18pix). So I haven't found my mounts limit yet and suspect my limit may be hit before my mounts.