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Strange issue with mount alignment model & astrophotography tool plate solving to center my target totally fighting eachother

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#1 dclt

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Posted 25 February 2021 - 10:47 PM

Or at least that's what I think happened, but I'm having a tough time diagnosing why the issue I had occurred. I'm using a celestron AVX mount, which requires first connecting to Celestron's CPWI software, which is the only way to open up the ASCOM drivers for the mount itself.

Also, I should add that I am very, very new to astrophotography so still working through some fine tuning things.

So, night 1- got well polar aligned using sharpcap pro before turning mount on. Got what sharpcap categories as an "excellent" alignment, so polar alignment was solid before doing anything else.

Then set mount in home position, and connected to CPWI software and did a "quick alignment" procedure, which is a zero star alignment. Basically it is no alignment at all. These are the minimum requirements to make CPWI happy so I can move on to using other tools.
I slewed manually to a bright star to get my imaging camera in focus, went back to index marks, opened Stellarium in the background and pulled up APT to use point craft to plate solve and center my target. I synced it to the mount, so it knew the mount coordinates, expecting it to be off, but at least in the same general area of the sky. No dice. It went totally in the wrong direction.

I should add right here that I already had the pointcraft settings in APT set with the "make relative goto ++ moves" checked to on, so it theoretically should have been able to make minor corrections to my mount pointing based on where the mount coordinates were before the goto ++ move. At least that's how I understand how that should work. Also at the time I had it set to ASTAP for blind solving & plate solve 2 for near solving & I have all the proper indexes installed, etc.

Ultimately I decided to go back to CPWI and do a 3-star alignment manually before having it go to my intended target, M46. Once there, I went back to APT, syncing it to the mount first & it read the same mount coordinates that showed in CPWI & also in Stellarium. I had point craft near solve, which it did successfully. At that point I tried to have APT go to the same target, M46. I expected a very minor move to center it. Instead, it started slewing the mount completely back in the opposite direction, and not just that, turning the scope downward so that it was on a path to drive itself into the mount (I think maybe in an ill fated attempt to do a meridian flip I'm not sure. M46 was approaching the meridian at that time, but still a good half hour from reaching it.). I aborted the goto immediately. I still cannot understand why this happened.

SO...I powered the mount off, went back to index marks, did manual star alignment all over again through CPWI, but did not have CPWI do a go to back to M46. Instead I went to a different part of the sky and pointed at Pollux, where I new I'd be starting from very well on the same side of the meridian as my target, M46. I then synced mount in APT (once again it correctly displayed the mount's actual coordinates) and did blind solve successfully. Once more I attempted a goto to M46 from within APT. Once more it went COMPLETELY in the wrong direction and attempted again to drive the telescope in a dangerously wrong angle.

I should mention that while all of this was going on both Stellarium and CPWI showed the same mount position at every point both with the coordinates and on their skymaps.

Night 2- once again began with an excellent polar alignment using sharpcap. Then went to bright star manually to focus. Then moved back to index marks and turned mount back off completely before doing a quick alignment (zero star alignment) through CPWI to satisfy it, pulled up stellarium in background where it connected to my mount, then went to APT synced it to the mount coordinates & had it blind solve from where it was successfully. Then I once again asked it to goto M46 & it went in the totally wrong direction, not even close. It pointed itself at a tree in the opposite direction of M46, so could not plate solve to fix it. I got frustrated, started over & did a manual star alignment through CPWI, had CPWI goto M46, where I knew it wasn't perfectly centered without plate solving, but I started guiding, and began imaging because it was a week night & I could only stay out so late.

Now I am obviously missing something here, but I'm a little stumped. Please advise. Thanks

Edited by dclt, 25 February 2021 - 11:48 PM.


#2 dclt

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Posted 26 February 2021 - 12:08 PM

Bueller, bueller? Anyone?

#3 Tapio

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Posted 26 February 2021 - 12:39 PM

First thing that comes to mind - make sure you have same latitude & longitude and date & time information in every software you are using.



#4 dclt

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Posted 26 February 2021 - 01:17 PM

First thing that comes to mind - make sure you have same latitude & longitude and date & time information in every software you are using.


This is not a time/date/location issue. I should have mentioned that in the original post. The correct time/date/coordinates were in CPWI, which communicates that through ASCOM to everything else throughout all of this.

#5 Tapio

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Posted 26 February 2021 - 02:02 PM

Okay so you have APT setting 'Import coordinates from ASCOM' ?

And something similar in Stellarium ?



#6 dclt

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Posted 26 February 2021 - 02:14 PM

Okay so you have APT setting 'Import coordinates from ASCOM' ?
And something similar in Stellarium ?


yes I do. And in the instances described above I made sure that had occurred in APT before attempting plate solve & goto ++


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