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Old 04-08-2012, 09:06 AM
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silv (Annette)
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Join Date: Apr 2012
Location: Germany 54°N
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found the "blog" related to the periodic error graph you linked.

I feel I might understand the whole thing sometime - but I don't, yet. Can't even ask questions, that's how blurry it all is, for me.

How come, a guiding setup can reduce the mechanical errors? They do still occur: the gears are still too tight or some screws not holding something properly even.
(I'm not going to do auto guiding. Feels like cheating. Wanna do it the puristic way, first. But answering this question above would help me understand a bit more of the underlying problem, I hope.)

Read this thread about tuning a NEQ6. To get a bit of feel for ... something.

Quote:
Then do a single 10 minute image with the RA track operating - leave the dec drive fixed - the dec drift will allow you to see what the RA axis does - you should see a sort of sinewave formed by the PE cycle.
"leave the dec drive fixed" - how would I do that? Connect the hand controller to the upper motor instead of the lower motor? (I assume they are both "motors" - both boxes have additional ports.)

What is it this 10 min exposure can tell me? A star trail that looks like a sinus curve?

2 of my nightly routines are:
* resetting PEC data in the controller (every setup is different in the alignment quality and if it is recording PE I don't want to use data from a previous setup.) I have no idea what the PEC really does. Apparently, the errors come from the motor wheels not being properly balanced and meshing into each other. How would PEC predict the next mechanical movement error and then how would it work against it? Slow the motor down or speed it up when approaching such a speed bump or a pot hole? (You wrote you don't use PEC. I'm just thinking loud.)

* sometimes using the "sync to target" option when the "select and slew" option has not put the object reasonably well within the FOV of the 40mm eyepiece. I will stop using this function, now, because I read somewhere that some controller software interpret this command as a "1 star alignment" and overwrite the sessions' 3 star alignment.
(Gotostar software is not well documented and outside support, anyway.)

Last edited by silv; 04-08-2012 at 09:52 AM.
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