M57 - The Ring Nebula

[steppenwolf]

M57 – The Ring Nebula (NGC 6720)

 

Introduction

I don’t know what it is about this object but finding it visually with a manual telescope has always proved to be a bit of a challenge for me! I don’t know if it is simply that it is so relatively small or what but I am always grateful for a GoTo mount when I am seeking it out. Visually it looks like a tiny smoke ring hanging in deep space but train a camera on it and it really comes alive.

This gorgeous object was discovered in 1779 by the French astronomer Antoine Darquier de Pellepoix in the constellation of Lyra. However, there is some dispute over this as Charles Messier wrote in his observations earlier in the same year that he had noticed a ‘small patch of light’ near the path of Bode's comet and it believed that this was the nebula

Typical of many planetary nebulae, M57 responds well to both broadband and narrowband imaging but my goal here was to bring out some of its outer halo and for that, the weapons of choice are in the narrowband domain. The nebula lies at a distance of approximately 2,250 light years from Earth and has an apparent visual magnitude of +8.8 h. The white dwarf at its core has a magnitude of +15.8 but this is not always visible in narrowband images.

Image Stats

Mount: Mesu 200
Telescope: Sky-Watcher Esprit 150
Flattener: Sky-Watcher Esprit specific
Camera: QSI 683 WSG-8
Filters: Astrodon 3nm Ha, 3nm OIII
Subframes: 30 x 1800 sec Ha, 16 x 1800 sec OIII
Total Integration: 23 hours
Control: CCD Commander
Capture: MaxIm DL
Calibration, Stacking and Deconvolution: PixInsight
Post-Processing: PhotoShop PS3

Location

Constellation	Lyra
RA	18° 54' 21.0"
DEC	+33° 03' 18.0"
Distance	~2250ly

 

 

[Kinch]

Well done. I don't know what it is about this nebula - I have tried it a couple of times and have not been successful......it is still on my to-do list. If I can match what you have done here - I will be happy.

[kirkster501]

Very difficult to process and bring out that elusive outer shell. Well done, I like your treatment of this. 

[michael8554]

If I lined up Sheliak and Sulafat in my finder, there was M57 in the middle !

First DSO I ever managed to find and image.

Michael

[steppenwolf]

9 hours ago, Kinch said:

Well done. I don't know what it is about this nebula - I have tried it a couple of times and have not been successful......it is still on my to-do list. If I can match what you have done here - I will be happy.

Thank you - it is well worth persevering with this object to collect some deep data to start with and then it is a matter of careful processing to bring out the halo even if it is slightly to the detriment of the core of the nebula.

8 hours ago, kirkster501 said:

Very difficult to process and bring out that elusive outer shell. Well done, I like your treatment of this. 

Thank you. Yes it is tricky and I used the various layers and masks in PS to achieve it. What did help though was the presence of the halo in the raw images as shown in the unprocessed annotated greyscale image which is just the Ha stack with STF applied automatically by PixInsight.

8 hours ago, michael8554 said:

If I lined up Sheliak and Sulafat in my finder, there was M57 in the middle !

I'm pleased that it doesn't give you the same grief it has given me in the past!

[Tommohawk]

Looks great, nice job!

The border on the outer shell looks a tad hard - maybe it really is that well defined? 

[Chris]

Wow! it's nice to see the outer shell, you don't see that on images too often. I managed to image this the other night also with a cheap achro plus ZWO120mm. Not quite the same result as yourself lol but pleased to have just captured it. 

[steppenwolf]

2 hours ago, Tommohawk said:

The border on the outer shell looks a tad hard - maybe it really is that well defined? 

Yes, it is that well defined - but it probably looks particularly sharp as it has a very thin outer ring of red which accentuates it.

1 hour ago, Lockie said:

Wow! it's nice to see the outer shell, you don't see that on images too often.

'Twas what I was aiming for specifically - there is another shell (and probably others too!) that is just starting to show as 'blemishes' in the image.

[david_taurus83]

Excellent! Even with a 150 Esprit it's small! Which outer shell is everybody referring to? I can see 2 🙂

[kirkster501]

With this object it's very hard not to posterise the colourful ring whilst simultaneously trying to drag out the outer shell.

[ollypenrice]

Very nice, Steve. The outer shells look excellent. 

Olly

[steppenwolf]

55 minutes ago, david_taurus83 said:

Excellent! Even with a 150 Esprit it's small! Which outer shell is everybody referring to? I can see 2

Yes, it really is small and this is a partial crop - -the annotated image shows the actual Esprit 150/QSI FOV

10 minutes ago, ollypenrice said:

Very nice, Steve. The outer shells look excellent. 

Thanks, Olly.

[simmo39]

Very nice, once we get the night back propper i will give this target ago again. Not done it for a few years.

[kirkster501]

It is very small with TEC140 as well.  I fancy a go at this with the Meade 14" ACF but a night good enough to support 0.33 Arcsec/pixel is rarer than dragon poo where I live.

[Ags]

This nebula has phenomenal surface brightness.

[steppenwolf]

On 16/05/2020 at 16:41, simmo39 said:

Very nice, once we get the night back propper i will give this target ago again. Not done it for a few years.

Well worth seeking out!

On 16/05/2020 at 19:25, kirkster501 said:

I fancy a go at this with the Meade 14" ACF but a night good enough to support 0.33 Arcsec/pixel is rarer than dragon poo where I live.

That could be an absolute cracker then!

On 16/05/2020 at 19:37, Ags said:

This nebula has phenomenal surface brightness.

Yes, it is very bright making it even more embarrassing that I have struggled in the past to locate it - mind you, that was with a 500mm focal length telescope so the object was really tiny!

[MartinB]

Great job Steve, you've done a really nice job retaining the contrast within the ring whilst pulling out the shell.  It's just reminded me that I imaged this in several years ago to get the shell and gave up!  I must go back and have another look at that data.

[steppenwolf]

57 minutes ago, MartinB said:

Great job Steve, you've done a really nice job retaining the contrast within the ring whilst pulling out the shell.  It's just reminded me that I imaged this in several years ago to get the shell and gave up! 

Thanks, Martin - yes it does take some doing to get that balance right. I really enjoyed processing this one though as the data held good promise from the start.

[Shibby]

Fantastic result. Great work on the processing! Would love to have a try for the outer shell myself, but not if it requires 23 hours - that'd take me months!

[steppenwolf]

5 hours ago, Shibby said:

Fantastic result. Great work on the processing! Would love to have a try for the outer shell myself, but not if it requires 23 hours - that'd take me months!

Thanks! One of the advantages of narrowband imaging is that all of the OIII and half of the Ha was captured during a bright Moon so it was a little easier to get done than you might at first imagine.