Thanks everyone!
Quote:
Originally Posted by Slawomir
Hi Lee,
Below are the results for the subs from my current project, measured in PixInsight.
Equipment: 4" doublet, 3nm narrowband filters, 15 minute subs and AZ-EQ6 (on average 0.5-0.8 arc seconds total tracking error), imaging at 1.33 arc seconds per pixel.
Site: Paddington in Brisbane
Ha: FWHM 2.5-3.3
S2: FWHM 2.1-3.2
O3: FWHM 2.4-2.7 (all in arc seconds)
Hope it helps 
EDIT: these results are for best/worst subs for each filter collected over 6 different nights. |
Definitely helps, thanks S! If it's not too much trouble (seriously, don't bother if it is), would you happen to know the median in each of those?
Quote:
Originally Posted by Shiraz
lee, further to Slawomir's post, if this is with your 100mm scope, scope diffraction from the relatively small aperture will broaden the stars a little - eg, if you measure 2.8 arc sec, the underlying seeing is about 2.5 FWHM and the scope will have bumped it up to 2.8.
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ha! Good point, Ray. I'd lost sight of that. Probably not a great idea to sample beyond the point of the diffraction limit, is it?
Now the question is, Dawes or Rayleigh? If we go with Dawes that's 1.16 for a 100mm 'frac.
Rayleigh I think is a better measurement since you can actually tell the points apart, rather than just identifying that there's two points.
Given a wavelength of 550nm (green), the Rayleigh limit on this scope is about 1.38". It goes up to ~1.65" in H-alpha, and drops to ~1.25" in OIII.
Either way, I'm oversampling here.... can't wait until I get that 8" newt ;-)