Plate solve error, always 15px

Hi all,
Today we had bad problems with plate solving and the center tool.
We did plate solve (, and that worked well but then we clicked on the image to center a star.
The center tool always lead to an error of -15,6 pixels. We tried several times, always had these -15,x pixels.

please let me know if there is something could habe done wrong.
We did use the function before and it did work well. The only change today was, that we put the Cam in another telescope. We correctly entered the new aperture and also the scale factor.
The guiding worked well, so the mount seems to do its job.
We do not know what to do now.

Thanks for your help!

why are the initial RA and DEC so different to the following ones? Are they not supposed to be similar. This looks to be a plate solve error?


You’ll have to forgive the regional inaccuracy, but the error here not -15,6 (-15.6), but rather -15642,1 (15642.1) pixels in RA. The reason appears to be that the mount is failing to converge to diminish the error (because SGPro is unable to sync with the mount to tell it its actual pointing position). When we attempt to sync we get:

[04.12.2016 21:01:32] [DEBUG] [Telescope Thread] ASCOM Telescope: Invalid Operation Exception in Sync : Sync matching failed. (System.Reflection.TargetInvocationException: Ein Aufrufziel hat einen Ausnahmefehler verursacht. —> System.Runtime.InteropServices.COMException: Sync matching failed.

An interesting observation is that the request to sync with your mount does not always fail.

Anyhow, not 100% sure this is the root cause but I can say the mount is not going where SGPro asks it to go:

  • Reference frame solved at center:

[04.12.2016 21:00:40] [DEBUG] [Telescope Thread] Astrometry.NET - RA: 4,05244682633333
[04.12.2016 21:00:40] [DEBUG] [Telescope Thread] Astrometry.NET - DEC: 36,391966524

  • SGPro requests slew to this location:

[04.12.2016 21:00:41] [DEBUG] [Telescope Thread] Telescope: Slewing to J2000 RA: 4,03331761463556 (04h01m59,94s) Dec: 36,3433304996433 (36°20’35,99")

  • Verify the position the scope ended up at:

[04.12.2016 21:01:32] [DEBUG] [Telescope Thread] Astrometry.NET - RA: 5,0356676794
[04.12.2016 21:01:32] [DEBUG] [Telescope Thread] Astrometry.NET - DEC: 36,367546221

About 15 degrees from where SGPro requested. We’d really need to see the mount’s logs to correlate what is going on here.

Hi Ken,

I think, our mount does not produce a log file, or we do not know where to find it.
The mount responded well on commands from theSKy (which has been turned off prior to using sgp) and with the 10Micron digital handbox.
Guiding did work without any problems.

In your last sentence, what do you mean with 15 degrees error?
SGP requested:
RA: 4,03331761463556 (04h01m59,94s) Dec: 36,3433304996433 (36°20’35,99")
and verified:
RA: 5,0356676794 DEC: 36,367546221

so the error in RA is 1 degree? in DEC 0,02?

Thank you very much for your help.
Best regards.

Sorry, I meant to say here that the deviation in what was requested of your mount and where your mount went was 1 hr (15 degrees).

We have plenty of TheSkyX users with no issues… maybe they can help out here with settings? In terms of producing a log, you’d need to check with Bisque.


several releases ago I had problems with plate solving of SGPro when using german regional settings on my laptop.
Probably that is fixed in the meantime, but if nothing helps, I would just give it a try and check the plate solving with setting your computer to en-US regional settings.

Best regards


Hi all,
Thank you for all your comment!
today we solved the 15 deg riddle

As Ken pointed out, that nicely corresponds to 1 hour.

We use two systems to sync the clock of the mount, but neither of them sycronized the daylight saving. It was still turned to ON in the handbox, and that did not wotk out good with sgp.
We did not think about the daylight saving at all and just found it by chance today when we had the same problems again.
Now we switched it OFF and the centering and plate solving works well again.

best regards and clear skies