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Old 15-09-2014, 08:06 PM
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AndrewJ is offline
Join Date: Mar 2006
Location: Melbourne
Posts: 1,905
Gday Andrew

For those who don't follow the Open PHD Guiding Google group the max duration warning should show up sometime soon.
As you are a member there, just another thought re warnings.
The mount i got the earlier plot from had a lot of underlying drift as well as very large PE ( even tho it was smooth ).
In some of the runs we grabbed, the "unguided" data for DEC looked horrible, but the error was semi masked when it was guided.
I traced this back to ( very ) bad calibration data, and what appears to be the way PHD converts between sensor and sky coordinates.
I see PHD2 calculates 2 calibration angles to convert the sensor X,Y into RA/DEC.
These should always be 90deg apart ( ie X to RA and X to DEC ), but in some cases we got ( IIRC) up to 90+/-35deg difference between them.
PHD then converted the data using the 2 separate angles and as such both the displayed data and sent pulses were wrong as the RA PEC was contaminating DEC data.
Not saying thats the case here, but it is another possible cause for oddball guiding.
I have no idea why PHD2 uses 2 discrete angles, as there is no way to properly measure the DEC angle due to the PE in the RA drive????

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