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Broken sgp platesolving


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I have an asi 294 mc pro, az gti and an asi 120mc. This platesolving has not been going to plan lately. I use platesolve 2 in sgp and it finds matches, but every attempt it makes to centre it it just gets worse. I have tried many solautions but none work. star aligment did not help.

Any help is appreciated

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The az gti is an AZIMUTH & ALTITUDE mount. Plate solving finds the position in RA & DEC. Somewhere the conversion from RA, DEC to AZ, ALT has to be done requiring the correct TIME, LATITUDE and LONGITUDE.  You should check these last three factors.

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So centering moves the scope in the wrong direction, away from the target instead of towards the target?

By roughly the correct distance, but the wrong way ? 

In Dec and Ra, or only one axis ? 

Perhaps you have accidently reversed the slew direction on that axis 

Or is it overshooting the target ?


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8 hours ago, TheMan said:

Sorry for being unclear. I have it on a wedge and in EQ mode. 

Note that if it is not polar aligned correctly, it will miss the target.  Thee RA axis should be pointing accurately to the celestial pole/polaris. So if your living 55 degrees north, the axis should be at 55 degrees elevation pointing north.

Assuming you it uses an ASCOM driver to communicate with the mount, you could also tests if the syncing is working using a planetarium program.  In planetarium program you can point to a star and request the mount to sync to that star position. After the sync the mount pointer should be at the star position.


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7 minutes ago, TheMan said:

it slews to the target, find the location, but after the correction the error in ra & dec increases.

Mix up of J2000 or Mean position could explain small errors.  An other possibility is wrong polar alignment of the RA axis.

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An other possibility is severe cone error ,https://www.youtube.com/watch?v=WatdQlPp22Y

but that doesn't explain the error increases after the sync.  I would check the communication equinox settings, switch of any modeling/correction in the mount if any and check the sync functionality using a planetarium program.

Or simply hysteresis in the mount?

What is the size of the error?

Edited by han59
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