Re: Tracking issues with an AP600e Goto


Tom, almost for sure your autoguider cable is the wrong cable. You need one where the opposite end of the cable is flipped over. What is happening is power is going to the East button instead of where it is meant to go and none of the other buttons will work without power.


On Tue, Nov 17, 2015 at 9:19 AM, tom_b@... [ap-gto] <ap-gto@...> wrote:


So I spent some quality time with the mount last night...
The first thing I did is to try the autotracking.  I couldn't ask for better performance.  In CCDSoft, the error reported was 0.2 pixels max over a 20 minute guided exposure.  So I figured this must have been a software issue.
Next I ran pempro to do a polar alignment.  That took the better part of 4 hours..It seemed that I either overshot one axis or the other.  After struggling with this it seems that the best I could do was a drift over 5 minutes of 40 arcsec in azimuth and 15 arcsec in altitude (yes arcseconds).  This seems to allow me to do a 10 minute unguided shot without a problem.
I then did a pempro  PE analysis on the mount.  The results were spectacular, and error of 1.8 / 1.1 arcseconds.  This was reproducable.
However, I then wanted to start using the mount for an image.  So I slewed to an object and tried to turn on autoguiding.  Well it picked up the star fine but after the first correction the star was gone.
So I did a recalibration and it was now impossible to recalibrate the software.  
What happened was this: The N, S, W movements were perfect.  The star image afterwards showed that it moved perfectly in the initial move and the return.  The E movement was another story!
When CCDSoft takes an image after moving, the stars are long trails.  It seems that in the E direction the mount keeps moving after the correction is sent.
Now, I can reproduce this manually.  In the autoguide screen of CCDSoft there are the N,S,W,E buttons to move the scope. If I press on the E button and take an image, the mount is still moving.  At this point if I do "Take image" again, it is still moving! and again!  Then it stops.
So it seems like the mount is getting the command to move and it is then taking 8 seconds or so to complete it, and we are talking a small amount of movement.
Now get this.  I went and slewed the scope around randomly for about a minute and then tried to calibrate again.  This time it was perfect!  So for the next 40 minute all was well, then I went to bed.
So, where do I go from here?

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