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Old 18-05-2016, 09:05 PM
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Shiraz (Ray)
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Shiraz is offline
Join Date: Apr 2010
Location: ardrossan south australia
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Originally Posted by codemonkey View Post
Ah, ok, thanks for the clarification, Ray. You mentioned "final stack" so I assumed they had been integrated.

There's a very clear trend in the charts that you provided, and the results are intuitive. That's what I'd hoped I was seeing in the initial charts.

From here, I think the next step is to evaluate the net gains of having more, sharper subs vs fewer less sharp subs.

Are the rejection algorithms good enough to provide a tangible benefit in the integrations? If you integrate 2x5s less sharp subs with 10x1s sharper subs, is the latter integration still sharper?

It might be interesting to do a drizzle integration as well, with a scale of 1, as this would avoid the sharpening effects of (some of?) the interpolation algorithms used in registration.
Will look at stacking over the next couple of days. - should be interesting.

Originally Posted by rally View Post
What was the frequency and range of the seeing changes that night ?

Next time try this with a DIMM (or a camera with dual apertures and appropriate software - a link exists somewhere on the net !) to measure the instantaneous FWHM and plot that.

I think you'll find there will be a correlation between the length of sub, period and range of seeing changes and the FWHM captured up to a point where Id expect it would plateau due to averaging.
Don't know the seeing statistics Rally, but I would not expect seeing to have any effect at all with periods of a minute or more (0.5 second guiding should clean up anything with a period longer than a second or so) - and yet there was no plateau up to five minute subs on both nights.

Have been toying with the idea of making a DIMM, but am not sure I want to put in that much effort and expense for now (a 10 inch+ SCT, a non-standard prism and half a grand's worth of software). Maybe when curiosity gets overwhelming).

Regards ray
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