Re: having guiding problems

Alan Voetsch <alanv12952@...>

Hey Roland,

--- chris1011@... wrote:

Another question: should i run a 'PEM' routine before the above? I have not
yet done so.
Not necessary unless you want to do unguided imaging. PEM is for periodic
error compensation. That means during any unguided imaging, you can drastically
reduce the priodic error (which is a very slow moving error that crops up after
tracking for a fairly long time period within the 6.4 minute worm cycle). The
error is small to begin with, between 3 and 5 arc seconds, so there is no use
trying to chase your guiding problems with yet another issue - an issue that
really does not affect guiding one iota.
I have to ask, because NOT getting rid of the periodic error is contrary to everything
I've ever heard. So, why would I not want to drastically reduce the error?

Many thnaks,


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