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Observation by Geof Lewis: M57 (LHaRGB) - Sept/Oct 2019

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Geof Lewis


Geof Lewis


2019 Oct 20 - 22:21


2019 Nov 03 - 13:12


The Ring Nebula (M57)

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Field centre

RA: 18h53m
Dec: +33°01'
Position angle: -177°40'

Field size

0°23' × 0°17'

  • C14 XLT
  • Optec Telecompressor (x0.7)
  • QSI583wsg-5
  • Astronomic Ha+LRGB filters
  • AP1200 GTO

L=107x120s; RGB=45x120s each; Ha=15x900s. All Bin2x2; -10C


Norfolk, UK

Target name

Messier 57 (Ring Nebula)


M57 (LHaRGB) - Sept/Oct 2019

About this image

This is my first attempt at capturing the outer halo of the Ring Nebula (M57). The data was captured over several nights during Sept 2019 and Oct 2019. I was unsure how to process and combine the data so pretty much it was trial and error with me making it up as I went.
My initial capture of Ha data in Sept was using too short (5 min) subs, so even though I had over 30 of them, I still struggled to show the halo and blending with the RGB data was not successful. After taking advice I increased the exposures to 15 mins and shot 15 new Ha subs in October. The halo was more clearly defined, but the combined HaR overwhelmed the core of the nebula, so I processed the L and combined RGB separately and used layers to retain the blue core.

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Geof Lewis
Geof Lewis, 2019 Nov 07 - 10:41 UTC

Hi Paul, thanks for your comments.

Yes, this one definitely required lots of patience. I initially captured 3 hours of Ha data using 5 min subs at bin 2x2, so actually more like 15 hours in total. I learnt the hard way that I need to shoot much longer subs with the Ha filter for this target and probably always, so I also had to shoot new darks to match. I tried to include the shorter Ha subs data, but it didn't work as well as when I excluded them, which is probably my inexperience in processing complex data sets.

Regards, Geof

Paul Leyland
Paul Leyland, 2019 Nov 08 - 16:52 UTC

That is a total of 11 hours, 49 minutes.  You're much more patient than I am!  Perhaps not too surprising after all that the outer portions of the nebula show up so well.

Nice views of the IC 1296 and MASX J18530959+3305385 galaxies too.

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