Messier 27 - The Dumbbell Nebula in Narrowband - 10.25 Hours — Cosgrove's Cosmos (2024)

Written By Patrick A. Cosgrove

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Date: Sept 15, 2021

Cosgrove’s Cosmos Catalog #0084

Published in the May 2022 Issue of Astronomy Magazine!

This image was highlighted in the reader’s Gallery Section with an excellent little summary of the image. This is the third image I published so far in 2022!

Thanks, Astronomy Magazine!

Messier 27 - The Dumbbell Nebula in Narrowband - 10.25 Hours — Cosgrove's Cosmos (2)

Messier 27 - The Dumbbell Nebula in Narrowband - 10.25 Hours — Cosgrove's Cosmos (3)

Published in Amateur Astrophotography Magazine!

April 9th, 2023 - In issue #111, p70-75. This image was published as part of a profile article on me!

Messier 27 - The Dumbbell Nebula in Narrowband - 10.25 Hours — Cosgrove's Cosmos (4)

Messier 27 - The Dumbbell Nebula in Narrowband - 10.25 Hours — Cosgrove's Cosmos (5)

Table of Contents Show (Click on lines to navigate)

A Special Note:

At a later date, I ended up reprocessing this image using new tools and techniques, creating what I believe to be a superior image. This can be seen HERE.

About the Target

Messier 27, also known as NGC 6853, the "Dumbell Nebula", and the "Apple Core Nebula" is a planetary nebula located about 1200 light-years away in the constellation of Vulpecula. It was the first planetary nebula ever discovered by Charles Messier in 1764. Planetary nebulae are formed when stars throw off their outer layers of gas as they reach the end of their lives. Based on studies made on its expansion rate, we can work backward to determine that the formation of this nebulae began about 10,000 years ago. Being bright and easily observable even with a small scope, M27 is famous and well known.

The basic form of the nebula is an oblate sphere with a dimension of about 8 arc minutes. There is a void on each side of the sphere, causing its characteristic shape. Given its size and inherent brightness, this shape can easily be seen, thus driving its popular names of the Dumbell and the Apple Core Nebula. Early observers debated whether this was a single nebula or two nebulae close together, and some wondered if the nebulosity consisted of unresolved stars. In John Hershels observing logs of 1833, he noted the following:

“h 2060 = M 27.

Sweep 166 (Auguat 17, 1828)

RA 19h 52m 8.6s, NPD 67d 43m +/- (1830.0) [Right Ascension and North Polar Distance]

(See fig 26.) A nebula shaped like a dumb-bell, with the elliptic outline completed by a feeble nebulous light. Position of the axis of symmetry through the centres of the two chief masses = (by microm.) 30.0deg .. 60.0 deg nf..sp. The diam of the elliptic light fills a space nearly equal to that between the wires (7' or 8'). Not resolvable, but I see on it 4 destinct stars 1 = 12 m at the s f edge; 2 = 12.13 m, almost diametrically opposite; 3 = 13 m in the n p quarter, and 1 = 14.15 m near the centre. Place that of the centre. “

He may have been the first person to use the descriptor of a Dumbbell - I don't know this for certain, but I can say that his observing logs were a lot more precise than mine ever were!

The Annotated Image

Messier 27 - The Dumbbell Nebula in Narrowband - 10.25 Hours — Cosgrove's Cosmos (6)

The Location in the Sky

Messier 27 - The Dumbbell Nebula in Narrowband - 10.25 Hours — Cosgrove's Cosmos (7)

About the Project

We had three clear nights in early September, those being on the 1st, then the 4th, and the 6th. I tried to find an interesting target for my AP130 platform with its newer ASI2600MM-Pro camera. I considered several possibilities but I finally decided on M27.

Target Selection

Why M27? It is certainly bright and well known - making it a pretty common astrophotographic target. When reviewing images of M27 in Astrobin, I found a long list of very similar images - mostly shot in OSC RGB or Mono Camera LRGB. I also noted that extremely few of these images were awarded "Top Pick" or "Image of the Day". I suppose when everybody and their brother is shooting such a target - after a while - it begins to lose its novelty, and the flood of such images makes it hard to notice a good one.

The other thing I noticed was that there were very few narrowband images of this object. I thought it might be interesting to have a go at that.

I have photographed this object twice before - once in 2019 (you can see that post HERE) and again in 2020 (you can see that HERE). Knowing what those looked like, I was curious to see how narrowband would look by comparison.

So I gathered three nights of data for a total of a little over 10 hours. I preprocessed the images and looked at the resulting Master Ha, O3, and S2 images in Pixinsight.

At first, the images seemed washed out and lacking in detail - at least until I started my processing. As I worked on them, I uncovered astonishing structures buried in the bright nebula, which I had never seen on M27 before. Even more interesting, I found that each image had a very different nature.

Image Processing Discussion

In this next section, I will provide an overview of the image processing done for this project. This is high level. However, I keep a processing log for this image, and that will be listed below for those interested in the nitty-gritty details of my approach here. I am not claiming this is the best or only way to do this - but it is what I did do, and I hope by including it that some are helped by it.

Now - let’s talk a bit about each image.

The Ha image had a huge and delicate - almost lacy - texture to the gaseous shell surrounding a bright core filled with knots and texture.

The O3 image was all smooth and rounded with loops of gases and an outer shell that almost looked like a butterfly's wings.

The S2 image was more constrained and looked more like the traditional view of the nebula - with the dumbbell shape - but it did have some interesting texture within. In fact, I could see what appeared to be a central star. I wonder if it is THE central star - but I don't really know. This star was not seen in either the Ha or the O3 images, as it seemed to be obscured by the gaseous nebula.

Based on the detail I saw, I undertook extensive efforts to maximize the quality of each nonlinear image prior to combining them to form the color image. This included carefully constructing a set of masks so that I could work selectively on the core of the nebula, the outer gaseous shell, and then the entire nebula altogether. I found that LHE (Local Histogram Equalization) and HDR-MT (High Dynamic Range Multiscale Transform) were my best friends in this endeavor. HDR-MT compressed the bright portions of the nebula, revealing detail lost In the bright haze, while LHE allowed these details to be enhanced. I also found MLT helpful when targeting features of a specific scale, as these could be enhanced.

This was a fascinating exercise because each image was so different and as I processed the images I was seeing detail that I personally had never before seen associated with M27.

As I completed the first phase, combining them and creating the color image was next. Since this was narrowband imaging, I had a lot of choices I could play with here. What would look best? Since this is all creating a false-color image, there is no right or wrong here. You want the esthetically appealing mapping or one that best shows key details from a technical perspective.

I typically use the SHO Hubble palette, but there is also the HSO "European" palette, The HOO palette (which seemed pretty popular with the few narrowband images I did find for this image). I also found some custom blend recommendations and tried a few of those.

So I created a few versions to explore what looks could be achieved. First, I took the Master linear images and created a color mapping version.

Messier 27 - The Dumbbell Nebula in Narrowband - 10.25 Hours — Cosgrove's Cosmos (8)

While these looked a lot like other images of M27 that I have seen - very little detail comes through the bright nebula. After finishing processing my nonlinear images and playing with some other mixes, I tried this exercise again and came up with the following series.

Often these mappings have a strong green coloration at first (usually due to the strong Ha signal swamping the other signals), and often you usually remove this bias with SCNR, which changes the value of highly saturated green pixels to something more neutral) and produces the series below:

Messier 27 - The Dumbbell Nebula in Narrowband - 10.25 Hours — Cosgrove's Cosmos (9)

These came out better, but I found two things very quickly:

  • It was not obvious which color mapping was best here

  • In combination - Some of the wonderful detail was obscured and lost!

It was clear that I had my work cut out for me!

Which Color Mapping to Use?

On the first problem - I reached out to friends and family, showed them several examples, and I got back some feedback that was surprisingly consistent - the SHO Hubble Palette was the image strongly preferred, while the "Mix 4" came in as a second. Some liked the HOO image, but most did not. I decided to do something that I have never done before - I would process Three versions of the image for the competition and then decide which was my favorite! When you can’t yet make up your mind, then don’t!

Avoiding Loss of Detail

On the second problem, I came up with an interesting solution.

Since I was losing the outer shell detail in the combination and some of the internal structure - and these mostly came from the Ha and O3 image - I decided to create a synthetic Luminance image by using a weighted combination of those two images. I experimented with various weights, but I used an equal 50-50 split between the two. Once I had this image, I then used LRGBCombination to fold it into the various flavors of color images. I found this helped clean up and preserve some of the detail that was important.

The resulting Images

So, in the end, I processed three flavors of this image, and I will share them here for you to consider.

Which do you like better?

———> Explore the Full Res Version of This Image Via Astrobin! <———

How does this compare with other narrowband images out there?

I am still surprised at the amount of structure I am finding here. I did not see many images in Astrobin with this kind of structure (maybe I just did not look hard enough), but when I did a Wikipedia lookup for M27 I found this image right away:

Messier 27 - The Dumbbell Nebula in Narrowband - 10.25 Hours — Cosgrove's Cosmos (10)

HERE is the link for this particular image

I also did a search for M27 narrowband images and there are some out there that show these details. This LINK will bring up a google search and you can see others samples - but even compared with all of those, I am pretty happy with the detail I uncovered with this effort.

Comparison with Previous Efforts

As I mentioned, I have shot M27 on two occasions previously. So how do these images compare? Let’s take a look:

The difference between the first and the second image is longer integration times, experience, and better processing. The last image, the current one, is in a class by itself. Longer focal length scope, superior camera, narrowband filters, gobs of integration time, and finally - much more sophisticated processing.

Critique of the image

So am I totally satisfied with this image?

No, I am not.

Even though I have over 10 hours on this relatively bright target, I think I could have gotten a better image with double that. Why doubling? To get the next level of quality in terms of the signal-to-noise, the rule of thumb is that you have to double your exposure. So 20 hours? Ahhh - if only I lived somewhere with clear skies, no trees blocking my view, and no smoke plumes to pester me! So this is probably not going to happen for me.

The other issue I have is the stars in this image.

If you look carefully, you will note that there are color rings around the stars. I am not sure where they came from and I have not found a good way to deal with them yet.

I suspect that when I am doing deconvolution, I am reducing the size of the stars slightly differently for each master image. When you first make your color image - this is not very noticeable. However, by the time you are done with your processing, you have stretched the tone scale and boosted the color in significant ways, and this can and does seem to bring them out.

With an LRGB image, the practice seems to be to do deconvolution only on the Lum image, and when you fold that into the color image, it takes on the job of delivering detail. In narrowband, some people use a synthetic Lum image, but I think most folks still apply deconvolution to all layers of a narrowband image.

As we saw in this image, there was very different detail in each master image Deconvolution reduces the size of the star image, but more importantly, it restores lost detail in each of the nebulae and structures in the image. I really want that detail.

Some people use star maps to protect their images from this. I have done that as well, but I find it can be quite tricky to get a star map that covers all of the stars and has the right-sized stars to manage the rings as well.

Others use starnet++ to separate the stars from the nebula and process them separately, and finally recombine them for the final image. I have done this too, but I seem to get artifacts from the process that I am very sensitive to, no matter how I do it. I think the accurate star mask is probably the right approach here, and I will have to work on developing my techniques here.

In the meantime, if you have a good suggestion on how to fix color rings around stars - I am all ears!

Image Processing Log

2. Blink Screening Process

  • All light images were reviewed with the Blink process.

    • Ha Images - 2 images with elongated stars were found and removed

    • O3 Images - 3 were rejected for elongated images

    • S2 Image - plane trails on one image, and two images with slight gradients seen - nothing removed.

  • Flat images - all looked good

  • Flat Darks - all looked good

  • Darks - looks like there was a light leak during capture - so an alternative older set of darks to be used

2. WBPP 2.1 Run

  • all frame loaded

  • setup for calibration only

  • Setup so each night lights are calibrated with each night’s flats

  • Pedastal image of 50 used.

  • Run complete with no issues

3. ImageIntegration

  • Run for each master image

  • Rejection set up for Winsorized Sigma Clipping

  • Sigma Low clip of 3.5 and Sigma High clip of 2.5

  • Low and Large scale structure rejections enabled and set to 2x2

4. Dynamic crop. All images are cropped to the same spec.

5. Deconvolution Prep

  • For all images

    • Object mask created

      • A nonlinear version of the image was created using STF->HT

      • Use HT to clip blacks and push stars and nebula to white

    • Create Local protection images

      • Run StarMasks with layers = 6, all else default

      • Adjust star mask with HT to boost star size - move the middle arrow to the 25% point

    • Create PSF image with PSFImage Script.

6. Apply Deconvolution

  • For all images:

    • Apply Object mask to the image

    • Set psf to the right one for the image

    • add the right local support image

  • Create 3 preview sections on the image

  • Test different global dark settings until optimal found

  • Ha global dark = 0.0009

  • O3 global dark = 0.002

  • S2 global dark = 0.0009

7. Run a Light NR pass to take the “fizz” off each image.

  • MLT used to do this with the following settings:

Messier 27 - The Dumbbell Nebula in Narrowband - 10.25 Hours — Cosgrove's Cosmos (11)

8. Create Nonlinear Versions of the Images

  • For each image

    • Select preview in an area of the clear sky background

    • Run MaskedStretch

    • Adjust with HT or CT to get good background sky levels and good image scale

9. Enhance Ha Nonlinear Image

  • Run GAME script - create a gradient ellipse around m27

  • Apply to image

  • Run HDR-MT with 8 layers, B3(5) to lightness only, use lightness mask

  • Run LHE with size 64, the contrast of 2.0, amount of 0.5, 8-bit histograms

  • Run LHE with size 140, the contrast of 2.0, amount of 0.5, 10-bit histograms

  • RangeSelection - adjust just to get the stars and core of m27

  • Apply to the image to protect the stars and core of M27

  • Run ACDNR lightness only, use mask above, with stddev 2.6

  • Run RangeSelection to get only the outer gas shell

  • Use Dynamicpaintbrushh - wipe out mask everywhere but shell

  • Apply the mask

  • Use CT to boost gaseus shell

10. Enhance O3 Nonlinear Image

  • Run GAME script - create graduated eclipse around m27

  • Apply to image

  • Run HDR-MT with 7 layers, B3(5) to lightness only, use lightness mask

  • Run LHE with size 64, the contrast of 2.0, amount of 1.0, 8-bit histograms

  • Run LHE with size 140, the contrast of 2.0, amount of 0.5, 10-bit histograms

  • RangeSelection - adjust to just get the stars and core of m27

  • Apply to the image to protect stars and core of M27

  • Run ACDNR lightness only, use mask above, with stddev 2.6

  • Run RangeSelection to get only the outer gas shell

  • Use DynamicPaintbrush - wipe out mask everywhere but shell

  • Apply the mask

  • Use CT to boost gaseous shell

11. Enhance S2 Nonlinear Image

  • Run GAME script - graduated eclipse around m27

  • Apply to image

  • Run LHE with size 64, the contrast of 2.0, amount of 0.5, 8-bit histograms

  • Run LHE with size 140, the contrast of 2.0, amount of 0.4, 10-bit histograms

  • RangeSelection - adjust to just get the stars and core of m27

  • Apply to the image to protect stars and core of M27

  • Run ACDNR lightness only, use mask above, with stddev 4.0

  • Still, some fine noise left, run MLT with 4 layers and remove the lowest two, using the same mask

12. Create four versions of Color Images: SHO, HOO, MIX1, Mix4

  • Use ChannelCombination to create SHO, Mapping S2, Ha, and O3 for R, G, B

  • Use ChannelCombination to create HOO, Mapping Ha, O3, and O3 for R, G, B

  • Use SHO-AIP script to create Mix2

    • Run Script

    • Load Ha, O3, and S2 files

    • Set Red channel weights as 70% Ha, 30% S2

    • Set Green channel weights as 70% O3, 30% S2

    • Set Blue channel weights as 100% O3

    • Create image

  • Use SHO-AIP Script to create Mix4

    • Load Ha, O3, and S2 files

    • Set Red channel weights as 80% Ha, 20% S2

    • Set Green channel weights as 100% O3

    • Set Blue channel weights as 85% O3, 15% Ha

    • Create image

13. Initial Process of the Color Images

  • For all color images

  • Use SCNR to get the green out

  • Boost sat and contrast with CT

  • Create synthetic Lum image

    • Run PixelMath to add Ha image + O3 image with rescaling

  • Run LRGBCombination add synthetic Lum image to color images

  • Run LHE with size 64, contrast 2.0, amount 0.15, and an 8-bit histogram

  • Run LHE with size 248, contrast 2.0, amount 0.15, and a 12-bit histogram

14. Fix Star Colors

  • Run RangeSelection to create a mask of just the object area

  • Use DynamicPaintBrush to remove all star images from the mask

  • Apply the mask to protect M27

  • Use ColorSaturation to reduce the color of stars to neutral

15. o Final Noise Reduction

  • Run ACDNR lightness Stddev of 1.5, Chrominance 2.5, use lightness mask

16. Crop Images

  • Run Crop to reduce images to 45% of normal size using the same aspect ratio

17. Star Reduction

  • Run EZ-StarReduction using everything default and the Adam Block Method.

18. Save images as Tiff and Move to Photoshop

  • In Photoshop:

    • Use Camera Raw Filter to adjust Global Clarity, Texture, and Color Mix

    • Use StarShrink filter to reduce large stars radius 46, strength 6, sharpness -1

    • Use StarShrink filter to reduce small stars radius 3, strength 6, sharpness -1

    • Add watermarks

    • Export Clear, Watermarked, and Web-sized Jpegs.

More Information

WikipediaWikipedia: Messier 27

SEDS: Messier 27

NASA: Messier 27 Messier 27

Capture Details

Lights Frames

  • Taken the nights of August 2nd, 3rd, and 4th

  • 39 x 300 seconds, bin 1x1 @ -15C, Gain 100.0, Astronomiks 6mm Ha Filter

  • 38 x 300 seconds, bin 1x1 @ -15C, Gain 100.0, Astronomiks 6mm OIII Filter

  • 46 x 300 seconds, bin 1x1 @ -15C, Gain 100.0, Astronomiks 6nm SII Filter

  • Total of 10.25 hours

Cal Frames

  • 30 Darks at 300 seconds, bin 1x1, -15C, gain 100

  • 30 Dark Flats at Flat exposure times, bin 1x1, -15C, gain 100

  • Flats done separately for each evening to account for camera rotator variances:

    • 12 Ha Flats

    • 12 OIII Flats

    • 12 SII Flats

Capture Hardware

  • Scope: Astrophysics 130mm Starfire F/8.35 APO refractor

  • Guide Scope: Televue 76mm Doublet

  • Camera: ZWO AS2600mm-pro with ZWO 7x36 Filter wheel with ZWO LRGB filter set, Astrodon 5nm Ha & OIII, and Astronomiks 6nm SII Narrowband filter set

  • Guide Camera: ZWO ASI290Mini

  • Focus Motor: Pegasus Astro Focus Cube 2

  • Camera Rotator: Pegasus Astro Falcon

  • Mount: Ioptron CEM60

  • Polar Alignment: Polemaster camera


  • Capture Software: PHD2 Guider, Sequence Generator Pro controller

  • Image Processing: Pixinsight, Photoshop - assisted by Coffee, extensive processing indecision and second-guessing, editor regret and much swearing…..

Click below to visit the Telescope Platform Version used for this image.

Click on link to see Platform version used for this image

Astro-Physics 130mm Platform


AP130 Version 2.0: Moving to a Next Generation Astro Camera…

Astro-Physics 130mm Platform


Adding the next generation ZWO ASI2600MM-Pro camera and ZWO EFW 7x36 II EFW to the platform…

Read More →

Astro-Physics 130mm Platform



Patrick A. Cosgrove

A retired technology geek leveraging his background and skills in Imaging Systems and Computers to pursue the challenging realm of Astrophotography. This has been a fascinating journey where Art and Technology confront the beauty and scale of a universe that boggles the mind…. It’s all about capturing ancient light - thosewhispering photons that have traveled long and far….

Messier 27 - The Dumbbell Nebula in Narrowband - 10.25 Hours — Cosgrove's Cosmos (2024)


What is the significance of Messier 27? ›

Spotted by Charles Messier in 1764, M27 was the first planetary nebula ever discovered. The term “planetary nebula” is a bit of a misnomer based on the nebula's round, planet-like appearance when viewed through smaller telescopes.

Is the Dumbbell Nebula easy to see? ›

The Dumbbell nebula can be easily seen in binoculars in a dark sky, just above the small constellation of Sagitta.

What is at the center of the Dumbbell Nebula? ›

The diffuse green glow, which is brightest near the center, is probably from hot gas atoms being heated by the ultraviolet light from the central white dwarf. A collection of clumps fill the central part of the nebula, and red-colored radial spokes extend well beyond.

Does the Dumbbell Nebula have a central star? ›

The nebula is about 1200 light years away and is 2 light years in diameter. The red glow is from ionized hydrogen and the blue-green from ionized oxygen. The remnant central star, visible in the photo, is a white dwarf. It is composed of hot dense matter, but lacks a fusion engine at its core.

What was Messier looking for? ›

Messier was the first in France to observe the anticipated return of Halley's Comet in 1758–59, and from that time he became an ardent searcher for new comets. Called the comet ferret by King Louis XV, Messier independently discovered 13 of them and observed many more.

What is the closest Messier to Earth? ›

M4, located in the constellation Scorpius, is a huge, spherical collection of stars known as a globular cluster. Just 5,500 light-years away, it is the closest globular cluster to Earth.

Can you see the Dumbbell Nebula with binoculars? ›

Although the Dumbell is not the only planetary nebula that is visible in 10×50 binoculars, it is significantly easier to see than any other, but will need a larger instrument with more magnification to show some structure. The progenitor star is far too faint to be seen, even in large binoculars.

What is the hardest nebula to photograph? ›

The Shark Nebula is made up of interstellar dust, which is so thick it hides most of the light from behind it. Dark nebulae like this one are often difficult to process because they are extremely faint, and are difficult to bring out from the background medium due to how dark they are.

Is the Dumbbell Nebula in the Milky Way? ›

Messier 27 (NGC 6853), also known as the Dumbbell Nebula, is a planetary nebula located in the constellation Vulpecula, in the Orion Arm of the Milky Way Galaxy in the Local Group of galaxies. M27 is 1350 light years away from Earth.

How big is Dumbbell Nebula? ›

What are the colors of the Dumbbell Nebula? ›

Blistering ultraviolet radiation from the super-hot star is causing the gases to glow. The red color is from nitrogen, and blue is from oxygen. To celebrate the 34th anniversary of the Hubble Space Telescope's launch, the telescope captured an image of the Little Dumbbell Nebula, or M76.

How big is Messier 27? ›

Is nebula a Stardust? ›

A nebula is a giant cloud of dust and gas in space. Some nebulae (more than one nebula) come from the gas and dust thrown out by the explosion of a dying star, such as a supernova. Other nebulae are regions where new stars are beginning to form. For this reason, some nebulae are called "star nurseries."

What is the significance of the Messier objects? ›

Since these objects could be observed visually with the relatively small-aperture refracting telescope (approximately 100 mm ≈ 4 inches) used by Messier to study the sky, they are among the brightest and thus most attractive astronomical objects (popularly called deep-sky objects) observable from Earth, and are popular ...

What is the meaning of Messier number? ›

noun. , Astronomy. a number (preceded by M) designating the 109 double stars, clusters, nebulae, and galaxies in the Messier catalog.

What is special about the galaxy Messier 87? ›

The elliptical galaxy M87 is the home of several trillion stars, a supermassive black hole and a family of roughly 15,000 globular star clusters. For comparison, our Milky Way galaxy contains only a few hundred billion stars and about 150 globular clusters.

What is the astronomical significance of Messier 57? ›

Messier 57. Discovered by Charles Messier on January 31, 1779. Observed by Antoine Darquier de Pellepoix in February 1779. The famous ring nebula Messier 57 (M57, NGC 6720) is often regarded as the prototype of a planetary nebula, and a showpiece in the northern hemisphere summer sky.


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