With the second anniversary of first light occurring just recently, on 2 Oct this year and after a total of 45 nights of imaging, producing 21 images in total, I had enough data to make a comprehensive assessment of the longer term seeing quality at Eagleview.
It was a bit of a task
but once I started, hey, I just kept going. It was an essentially manual method and it took quite a few hours to complete
To hopefully arrive at a statistically meaningful value, I went over every Luminance and H-alpha data set, checking the FWHM of many stars on many individual raw sub frames, from each of the 45 nights and selected the best 10 sub frames from each night (within an hour or so of the meridian in most cases) thus generally representing 30 to 60min of integration time over each night. Then, using MaximDL software, I measured the average FWHM of six non flat topped stars in each of the 10 sub frames and found the average of each set of 10 sub frames from each night. I used an x-axis resolution of 0.1 arc sec and I rounded down below 0.05 and up for 0.05 and above and the result is plotted below.
Due to limitations associated with the pixel sampling, there is likely a limit to the accuracy of this method for measuring FWHM below about 1.6" so it is unlikely to be a perfect assessment, however things that can be drawn from the result are:
1) Measured FWHM seeing-distribution across the two years, is between 1.4" and 2.3" with the most common FWHM value being 1.7" which is on par with
Siding Spring Observatory (typical raw sub frame attached)
2) 87% of nights see a FWHM of 2" or better, for at least part of each evening but often for hours at a time.
3) A FWHM of 1.7" or lower, is measured on over 50% of nights and 1.5" or less on 13% of nights.
4)
A big caveat - the scope used to make these measurements suffers from a small amount of astigmatism, so actual FWHM measurements, if done using the same method but with an aberration free optical train, would be somewhat better.
This was a fun exercise and it was good to actually graphically quantify the seeing at least to some meaningful degree
Cheers
Mike