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an attempt at lucky DSO imaging - Saturn nebula
Hi
tried out some lucky imaging with a 250f4 Newtonian and an ASI1600 camera operating on a 2mpix ROI. the seeing was fairly poor with normal 1 minute subs coming out at over 3 arcsec FWHM - the guiding was running at 1.3arcsec RMS, which is usually only marginally suitable for getting colour data. And a 3/4 moon was up.
The Saturn nebula is quite bright and I used 4 second x16bit subs for both lum and RGB. used SharpCap to collect the data - it has almost no time overheads. Selected luminance subs by hand and kept 498/~1000, based on image sharpness. The stack of selected subs came in at better than 2 arcsec FWHM, which was astounding based on the poor seeing - lucky imaging can certainly do the job on bright objects.
processing was interesting - after stacking, the only noise left was minor fixed patterns in the bias. With lots of short subs, the bias noise is more important than either the dark current or the shot noise in the background.
Attached image is a crop and rescaled 1.5x to around 0.5 arcsec pixel scale. Next step is to try it out with a Barlow - there is clearly a bit more resolution available with lucky imaging and it provides something to do if the moon is bright. Thanks for looking, Ray
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