Re: #APCC - V1.9 Tracking Error #APCC

Roland Christen

That looks perfect. No need for a new PEM curve. The PEM compensation is doing exactly as it should, it is removing the slight 2 arc sec wiggle in the RA tracking rate.

Bottom line, the mount runs very accurately and the only reason for the remaining drift is due to slight polar misalignment, telescope flex, atmospheric refraction, etc. In order to remove this drift, you either use modeling with APCC or guiding. So the next thing is to make a new model and try this same test with PEM ON again. Theoretically the model will compensate for the drift in the two axes whether PEM is on or off, but it only eliminates the drift and not the 2 arc sec periodic error that you see in your first run with PEM off.

I hope this makes sense to you. There should be no interaction between the model and PEM. They are as separate as the Moon is from Mars. There is no reason why having PEM on would cause the drift to come back, unless somehow when you turned PEM on, you might have inadvertently also turned off the model. Ray might be able to illuminate this further.

So for a final test, try making a model and doing this same PHD test again. With the model active and PEM turned on, you should get a flat line for both RA and Dec for at least 10 minutes, if not more.


-----Original Message-----
From: Rouz <rbidshahri@...>
Sent: Sat, Aug 28, 2021 2:24 am
Subject: Re: [ap-gto] #APCC - V1.9 Tracking Error

Now with the previous PEC curve and PEM ON.

Ra error improved slightly to 3.56 arc-sec peak to peak

I suppose I should run PEMPRO again and try for a better PEC curve?


Roland Christen

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