Re: having guiding problems


Dean Salman <cluster@...>
 

I have been wanting to get the PE in the mount but I can't seem to
get it working, I wonder if it is because I am under sampled. I kind
of gave up since I can do 20 second exposures ok.


--- In ap-gto@..., "Ray Gralak" <rgr@...> wrote:

Hi Roland,

If you want to reduce periodic error just for the fun of it,
then by all
means do so. Just do it and see what your results are.
I've experimented with various levels of periodic error in my
1200GTO mount
(not only did I reduce PE but I made it artificially higher for
testing by
loading an appropriate PE curve). Using a 5-second autoguider cycle
just by
turning on PEM reduced FWHM by 0.15 arc-seconds when going from 3.0
arc-sec
PE to 0.5 arc-sec . The stars looked just as round in each case,
but the
FWHM of the stars with PEC on were tighter.

Also, for those autoguiding through a narrowband filter with an
SBIG camera,
good PEC is critical. It will allow you to increase the autoguider
exposure
time to get a guide star through the narrowband filter.

-Ray

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