Taking advantage of the recent run of clear nights just following the new moon. Same technique as in my previous posts of galaxy pictures. Luminance from a large quality-selected stack (500-1500 frames) of short (10s) highly sampled (0.41 pixel/ arcsec) mono camera images from a large 12 inch F4 telescope was further sharpened using RC Blur Exterminator - and then applied as luminance to an OSC RGB camera image.
A few things that I have learned in applying this technique.
1) It can work well - and even before sharpening - it is possible to get LUM images at FWHM 2 or less under B6 Thames valley skies
2) But it needs a bit of luck. We had about a week or so of moonless nights and high pressure -- but there were only quite short windows of high transparency combined with steady skies.
3) It also requires a lot of imaging because at least half the frames will be discarded during selection
4) (Obviously) far easier with objects that remain close to the zenith
5) It is a technique only really applicable to brighter - or to the brighter parts of - galaxies. Even with a 300 mm mirror darker skies and/or subs longer than 10s (and therefore more blurring) are necessary to get adequate SNR into the luminance of more distant galaxies and faint outer spiral arms etc.
Having said that I think it has worked well for getting this close in image of the whale galaxy - NGC4631 - and its companion. A side on view of an active spiral galaxy the image is very reminiscent of M108. Here 755 x10s of luminance (ASI294MM) was used to inform a 472x40s of OSC (ASI294MC) RGB image. Capture in Sharpcap 4.1 and processing in PixInsight 1.9.
Tim
LRGB of the the whale and pup galaxies
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Please upload large images to photo sharing sites (flickr, etc) rather than trying to upload them as forum attachments.
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Please upload large images to photo sharing sites (flickr, etc) rather than trying to upload them as forum attachments.
Please share the equipment used and if possible camera settings to help others.