Re: Interesting Behavior with APCC Pro and Pegasus Astro UPBv2
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I wanted to revisit this topic with an update.
I reached out to Pegasus Astro, and they are aware of the issue with unit in the temperature value. At this time, they can’t fix it because SGP apparently has a dependency on the current behavior. They are reaching out to the SGP folks to see if they can coordinate a proper fix.
Regarding my unguided imaging results, I switched the units back to metric in the Pegasus Astro software, and that fixed the incorrect temperature in APCC Pro. I ran unguided again last night, and it was a slight improvement over the previous unguided session, but still wasn’t satisfactory. I forgot to note yesterday that I have my camera oriented so that declination in up/down in the frame. The elongation is diagonal, and flips 90 degrees after the meridian flip. That means that the components of drift are not isolated to either axis in particular.
So I went back to take a closer look at the model in APCC. I played with setting and clearing different terms to see the effect on the model. When I was doing this, I noticed that the “Correct for Refraction” checkbox was cleared. When I checked that box, the east and west scatter plots dropped from 53.35 and 50.20 arc seconds, respectively, to 9.42 and 6.32 arc seconds.
In my head, I assume that drift due to refraction will be aligned perpendicular to the horizon, instead of being aligned with one of the axes. If that’s true, then my elongation might be up/down, relative to the horizon. I’m going to give it another run tonight and see if I get better results with refraction correction enabled.
From: firstname.lastname@example.org <email@example.com> On Behalf Of W Hilmo
Sent: Tuesday, April 20, 2021 7:10 AM
Subject: Re: [ap-gto] Interesting Behavior with APCC Pro and Pegasus Astro UPBv2
Thanks for the response.
I’m using the latest version of the Pegasus Astro software for the UPBv2, so it sounds like I need to contact them regarding the temperature reporting issue. I’ve not yet confirmed that after switching back to Celcius, that it restores the unguided accuracy. I should be able to give that a try tonight.
As for the Advanced Sequencer, I saw it for the first time yesterday. I was expecting a UI similar to the original sequencer, which it’s not – but I think that it’s better. I really like to flexibility. I’m already thinking ahead to when Astro-Physics updates APCC to support the new few-stars tracking model that they introduced with the Mach2. It would be really cool to write a script to sample and plate solve 6 or 8 points along the target’s declination for unguided imaging, and then have NINA invoke the script at the start of an imaging session.
You may need to update your Pegasus software to fix this issue.
Older versions of the Pegasus UPBv2 console app and ObservingConditions driver will relay the Fahrenheit temperature to downstream consumers such as NINA or APCC when the console app is set to display units in Fahrenheit.
The ASCOM ObservingConditions interface specification specifies that the values for its various meteorological properties must be in SI units (ie, Celsius when it comes to temperature), so that is what APCC is expecting. Pegasus issued a fix for this last year so you might just need an update unless they’ve reintroduced the bug in a recent version.
This issue was even more obvious to those who have NINA set to convert the SI units too imperial for display. This caused NINA to convert the Fahrenheit temperature to Fahrenheit again, resulting in some outlandish temperature values being reported.
Aside from that, your description is quite an interesting depiction of how much temperature can alter the tracking of the mount under a model, though. Glad you were able to work out the cause. Hope you like the Advanced Sequencer, too. It is of course a work in progress but it’s maturing nicely.