Re: Interesting Behavior with APCC Pro and Pegasus Astro UPBv2

Ray Gralak

Hi Wade,

Question for Ray: Would it be interesting to validate the current model before making a new one?
Remind me, which scope, image scale, and exposure duration are you using?

If you are going to do a validate, you would want to do a "Model 5x and Park", which is an option in APPM. This will repeat the points five times and then park. This provides a measure of pointing accuracy and repeatability. For instance, if something is loose or optics are moving, variations from each pass may indicate this.

After doing this, you would have to send your logs and PNT files to Howard or me for analysis.


-----Original Message-----
From: [] On Behalf Of W Hilmo
Sent: Friday, April 23, 2021 6:16 AM
Subject: Re: [ap-gto] Interesting Behavior with APCC Pro and Pegasus Astro UPBv2

One more update:

tl;dr: Inconclusive.

The last couple of nights has been tough. We had a weather change and Wednesday night was a loss. Early
evening was clouded over, so when NINA started the run, the centering and focusing failed. I stopped the
sequence, changed the start time to 1:00am and then started the sequence again. It should have been clear at
1:00, and it probably was, but the second run of the sequence failed. Specifically, it didn't unpark the mount.
This is probably my fault, for using the mount while NINA was paused waiting for time. I suspect that NINA
thought that it had already unparked the mount, but I had manually parked it to avoid it tracking past the
meridian, since my target transited just before midnight. Anyway, at least I learned a few things about my
automation software. I'll avoid changing the state of the system while NINA is waiting.

Last night was clear, but seriously windy. I have a few subs where the stars have tails in the RA direction on
both sides. I'm guessing that these were particularly strong gusts, and I'm seeing the encoder putting the
mount back where it belongs. The good news is that, even though the wind was howling all night long. Only
about 3, out of 48, ten minute exposures show this behavior. The system in general seems pretty resilient to
wind. Once I get the observatory built, I suspect that I won't have any wind problems.

As far as unguided tracking, I have a few subs with round stars, and I have lots of them with egg shaped stars,
elongated in a different direction that the RA oscillations I mentioned above. The magnitude of the elongation
seems smaller than it was before I discovered that refraction correction was disabled.

At this point, it's going to be a few days before we get clear skies again. I think that I'm going to redo the model
for the next run (and I did verify in the PNT files, that the temperature was correct at the time I made the current
one). I'm using a portable field pier, so it's possible some settling has occurred (but it's been there for a while).

Question for Ray: Would it be interesting to validate the current model before making a new one?


-----Original Message-----
From: <> On Behalf Of Dale Ghent
Sent: Wednesday, April 21, 2021 2:29 PM
Subject: Re: [ap-gto] Interesting Behavior with APCC Pro and Pegasus Astro UPBv2

Thanks for the update on this.

Wow, so I thought they had fixed this in the past because it was reported by some NINA users, then I was
informed that Pegasus fixed it. I guess not. I run my own gear in metric all the time so I never noticed that it
actually hadn't been fixed. I just tested on my UPBv2 and, yeah, the fahrenheit value does make its way
through the ASCOM driver.

Ugh. The hold-up for a fix really validates me putting my foot down and saying "no, get them to fix their bug"
whenever a user asks us to implement a workaround a vendor's bug. Downstack defects should be addressed
directly where they are, and here's a rather perfect illustration as to why. Getting it fixed might take longer, but
everyone upstream wins in the end. IMO Pegasus should just press on and issue a fix because it's critical data
that is impacting other apps in an operational way.

I will be very interested to see your refraction-compensated results. I'm now trying to convince my club to
spring for APCC Pro so we can do unguided imaging on the serviced 1200GTO. Brian's image was a fantastic
example of this, and you A/B'ing with refraction comp. might help drive home the point if it is indeed the source
of your slight tracking imperfection.

On Apr 21, 2021, at 16:12, W Hilmo <y.groups@...> wrote:

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

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: <> 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


From: <> On Behalf Of Dale Ghent
Sent: Tuesday, April 20, 2021 4:34 AM
Subject: Re: [ap-gto] Interesting Behavior with APCC Pro and Pegasus Astro UPBv2

Hi Wade,

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

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.

On Apr 20, 2021, at 00:35, W Hilmo <y.groups@...> wrote:

I've been doing some unguided imaging with my AP1600 w/Absolute Encoders and APCC Pro and have seen
some interesting behavior with unguided imaging.

The first few nights that I run unguided after building a model of about 180 points, everything was great. I
was blown away by how well it worked. The last few nights, not so much. I am seeing elongated stars and
some image drift over the course of the night.

I do not believe that this is flexure. I'm imaging with my AP130GTX, and I've double checked all connections.
I've double checked to make sure that the pointing model is enabled. I verified that the polar alignment is still
spot on. It's a bit difficult to troubleshoot because, without guiding, there aren't any log files to examine. All I
have are the subs that I can inspect.

Since we're getting into more moonlight, I've done some software updates (switched to the daily builds for
NINA so that I can use the advanced scheduler). I've also set up for doing tonight's run with the guider enabled
so that I can get some logs. As I was watching the session get started, I noticed something odd. Specifically, I
noticed that APCC reported the temperature at over 40 degrees C, which is very wrong. I am using the
Pegasus Astro Ultimate PowerBox v2 as the weather sensor.

It occurred to me that I made a change to the Pegasus software a few days ago to change from reporting the
temperature in C, to reporting the temperature in F. It looks like both APCC and NINA are reporting the
Fahrenheit value as Celcius. I am wondering if the significantly incorrect temperature interpretation has
effected the model such that it's lost accuracy. I have reverted the Pegasus software back to reporting in C,
and after tonight's run, I'm going back to unguided operation to see if I get that great result back that I was
getting the first couple of nights.


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