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Stellarium, PHD2, and Plate Solving ---The Target Reticle Moves; Is this normal?

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#1 djronnieg


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Posted 04 February 2023 - 03:18 PM

I'm running Stellarium wit the "Stlellarium-scope" plug-in, so I launch the shortcut, connect to my mount and EQMOD pops-up. From there I click "Start Stellarium" and can select a target (as soon as I've "unparked" the mount).


In my current config, I click the the desired object in Stellarium and then press "CTRL+1" in order to command my mount to slew to the target. This all basically works as it always did. In the recent months I've started using Plate Solving. Early last year I had some trouble w/ plate solving but I was able to overcome those issue. Now, I can select a target.. solve... re-center the target, and I'm good to go! 



However, I noticed something odd.. maybe it's not odd? I always do run the plate solver before I engage PHD2. Before I run the plate solver, Stellarium will show the crosshair reticle on top of the target. Upon solving, it'll ask me if I want to "sync" and I'll click "yes". After "syncing", the target reticle in Stellarium will shift to it's updated and correct position. After that, I select my target and slew to the target once more.. at which point it is nearly in the center of my frame in my capture software. From there, I lock-on to a guide star in PHD2 and engage auto-guiding. 


While PHD2 is issuing "corrections" (guide north/south east/west), the crosshair reticle in Stellarium will gradually move. I never noticed this before, is this normal? 



I should add that my PHD2 might be working a bit hard due to a potential need for me to overhaul my mount (cleaning, lubrication.. might replace the bearings soon and "supertune" it). I was able to track the comet's nucleus last night but didn't dare use the actual comet tracking feature because intermittent clouds prevented me from checking and adjusting my polar alignment. I think the behavior described above is normal but that it might be exaggerated (the reticle may have move a lot less during guiding) due to the need to tune the mount. I've noticed the same "issue" (the moving reticle in Stellarium while guiding) before even with "perfect" polar alignment. 



I can't help but wonder... why Stellairum-scope isn't "aware" of auto-guiding. Like, if my mount is being given corrective pules surely it would make sense for the crosshair reticle in Stellarium to be updated with that information instead of dancing. Even if the movement of the reticle is exaggerated due to mount issues/imperfections, I'm surprised this is how it works, although I suspect I wouldn't notice it if it was more subtle. In any case, Plate Solving has made this situation very tolerable. 

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