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My Precious - M57 RGBHaOIII

PhotoGav

By PhotoGav
in Imaging - Deep Sky

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PhotoGav

PhotoGav

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The short summer nights make data collection a very long and drawn out affair, with just an hour or so collected each night in 'sub-standard' nautical darkness (good thing is, Astronomical darkness is back from tonight!). So, the thirty one hours of data for my image of M57 - the Ring Nebula - was collected over twenty nights in June and July. That in itself is amazing, twenty nights good enough to image in two months - I'll take that!

As for the object, M57 is a planetary nebula about 2,300 light years away in the constellation of Lyra. It is the result of the collapse of a Sun-like star ejecting material out into space, leaving a white dwarf as the core remnant. The nebula is currenly about one light year across, with the material expanding at a rate of about 40 km/s. It will eventually dissapate and merge with the interstellar medium in about 10,000 years, so I got this one in just in time. M57 is particularly interesting as it offers a glimpse of the ultimate fate of our own Sun, though the event is likely to be less spectacular as the Sun is several times smaller than the star that formed the Ring Nebula. There is a bonus object in the frame too, the spiral galaxy, IC 1296, at approx 260 million light years from Earth is clearly visible at roughly 11 o'clock about a ring nebula's distance away from M57.

Technial details:

Celestron EdgeHD 8", QSI 683-WSG8, Baader 1.25" filters, HEQ5 Pro.
RGB = 12 x 600s each
OIII = 18 x 1800s
Ha = 32 x 1800s
TOTAL = 31 hours

M57-LRGBHaOIII-11-Final.thumb.png.f0d5ca8738e69908c3f77dc95b1b96b2.png

Overall I am happy with this image and am particularly happy to have caught the outer layer - that was a pleasant surprise as the Ha data started coming in, I hadn't expected to see that at all. What is even better is that there is a hint of the outer outer layer - it's pretty subtle, but it is definitely there! The image has the usual SCT softness from the EdgeHD, nothing I can really do about that, the opportunity cost of the 2032mm focal length. Guiding is always challenging at this scale of 0.55"/pixel and I was generally in the region of 0.6" - 0.8" RMS in PHD2. Not bad from the old HEQ5 Pro mount, but it is well below the recommended half the pixel scale guiding error - hence the softness I guess. Anyway, I do enjoy revealing these small apparent size objects with the 8" and will just have to settle for the quality until I can upgrade my mount to bring the error down. Unusually I didn't shoot any Luminance data for this project, instead I used the new 'multi-channel' processing option in APP and created a Super Luminance layer from all the RGB, OIII and Ha data. It seems to have worked pretty well. Another first in this project was that I used the 'start time' feature of SGP, setting everything up with a start time of 23:30 and finish time of 02:30 or whatever, pressing 'Run Sequence' and retiring to bed at a reasonable hour, with the system poised ready to start itself up and grab the photons. I did enjoy waking up to a folder full of data in the morning - SGP is simply great!

I hope you like the image and I look forward to reading your comments.

Clear skies to you all!

 

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Craney

Craney

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Oh yes! , what a great image.  There is something gaseous going on outside of the usual 'ring'..... and also there is a spiral galaxy in there that I have never been aware of..

Great thread title as well.  ?  ( it does become an obsession doesn't it ??)

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Tim

Tim

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Really nicely presented Gav, it isn't always easy to combine the 5 filters into something appealing, but you have nailed it here.

I'm going to tease you now by suggesting you go even longer and try and capture the outer-outer rings, you have just a hint of their brighter parts at the moment. They only show in Ha, and require very long exposures and lots of them, not the easiest :)

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PhotoGav

PhotoGav

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Thank you all for the positive feedback.

I agree, it’s a great target to observe through a scope, a regular favourite in the Marlborough College Observatory outreach sessions that I’m involved in. It looks like a smoke ring to me. I’ve never seen the galaxy through a scope though!

As for combining the five filters - the RGB combine tool in APP made that a pretty simple task. Ha was mapped to red 50:50 with the Red data and OIII was mapped to Blue and Green, again at 50:50 in both channels.

Sara, I was very pleasantly surprised by the star colour - I normally struggle with any decent colour there, but for some reason it has held the colour this time. I adopted a slightly different approach in processing, saving about five or six versions at a wide range of stretches that I composited together to maintain exposure across the Ring Nebula itself. I think that perhaps inadvertently this has saved the star cores too. I always love accidental success!

Tim, you’re being silly now with the challenge of finding the outer-outer layer. How long would the exposures need to be? I used half hour subs in this version. I think what I really need are darker skies...

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PhotoGav

PhotoGav

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Thank you Richard, Chris & Barry.

Barry - I nearly called the Wilson PI Helpline as I wanted to try a bit of PI deconvolution, but unfortunately my trial has run out... I’m working on plucking up the courage to fork out the cash!

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Rodd

Rodd

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You have succeeded in banging your head through the wall!!  Your dedication paid off...great image.  Since you mentioned softness, I am wondering if you notch down the brightness a tad in the ring--just a touch, will the color boost (it will appear more colorful) help it appear a bit less soft?  I think the same would be true for the middle (but careful you don't over do that area).  I think this may accentuate the envelope too.  Just a theory!  

Rodd

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PhotoGav

PhotoGav

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Thank you Olly. Congrats on your image of The Hidden Galaxy making the IAPOTY shortlist (is it a winner??!). Are you going to the awards dinner? I have an image on the shortlist too and will be going - would be great to meet up if there.

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ollypenrice

ollypenrice

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On 27/07/2018 at 09:21, PhotoGav said:

Thank you Olly. Congrats on your image of The Hidden Galaxy making the IAPOTY shortlist (is it a winner??!). Are you going to the awards dinner? I have an image on the shortlist too and will be going - would be great to meet up if there.

I doubt I'll be able to go, Gav, but it's a joint project with Tom so he'll be there. Well done on making the shortlist.

Olly

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PhotoGav

PhotoGav

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10 hours ago, ollypenrice said:

I doubt I'll be able to go, Gav, but it's a joint project with Tom so he'll be there. Well done on making the shortlist.

Olly

Thanks Olly, it’s quite a thrill! Shame you won’t be there, but I will definitely seek out Tom.

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