Re: ATM Worms and gears

[Andy Hochstetler <andyhoc@mindspring.com>]

Mel Bartels wrote:
<< Automatic guiding can in theory correct for periodic errors of the
drive, but in practice, I have found that if PEC routines are
instituted, the automatic guider has a better go of it.  So, I still
recommend including PEC in addition to the autoguider.
>>

So basically, the preferred method would be using PEC to remove the larger 
errors found in the worm and gear and then use the guiding to help 
eliminate those smaller errors that PEC is unable to handle.

<< response time required is faster than CCDs can
capture/transmit/process, though some sort of training loop at the
pre-exposure for real stage might solve this...
>>

Is this because it takes awhile for the CCD to "pick up" the image and 
recognize it?  Do the newer CCD's help with this?  Or have the improvements 
been mostly in resolution, but not sensitivity or response?  Or is the PC 
not able to process the images fast enough?

Being a little naive about guiding, I guess I kind of need a lesson or two. 
 I had thought that the guider would pick up on a "guide star" and then 
based on detected variations in RA it would issue an adjustment to the 
controller for the RA stepper motor.  Is this about right?

Could this also be used in conjunction with DEC to help correct problems 
with polar alignment?

Thanks.
Andy H.