On Wed, Aug 19, 2020 at 02:03 PM, Arun Hegde wrote:
A bit curious how much value there is in a PEC exercise unless you have a really large and high frequency PE; you could detect if you have this by running GA in PHD2. I would think it depends on your skies? Under SE Wisconsin skies, without PEC, I consistently get an average of 0.65" RMS with numbers sometimes as low as 0.45" RMS.?
If your PE is fairly slow changing and smooth, then the value of PEC over guiding is reduced as the guider can correct before the error becomes large.
That said, with good PEC you can reduce the frequency of corrections resulting in less chasing of seeing and less need to find a high quality guide star. At shorter focal lengths you may even get away with no guiding. And then, any error that an autoguider corrects is most likely already has happened, so it already has lowered the resolution a little. In your case, it doesn't sound like it'll be a huge improvement, but even an improvement of 0.2" on FWHM of 2" is not a bad thing, and may even become noticeable, especially at smaller pixel scales/longer focal length.
Regards,
? ? -Paul
Paul Kanevsky