Messier 57 - A Reprocess of The Ring Nebula - 14.7 hours in LHaRGB!
Date: May 16, 2023
Cosgrove’s Cosmos Catalog ➤#0119
This version of M57 was a complete reprocess of image data collected in July of 2022. (click for full res version via Astrobin.cm)
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A Reprocessing Project
I have now recovered from my operation and am raring to get out and capture fresh photons, but I have been stymied by smoke plumes from fires in Alberta, Canada, riding down the jet stream to obscure my skies!
Since I cannot collect new photons, I decided to reprocess some old ones!
I was very proud of my M57 image that captures the Ha outer gas shells. This image has been published in Amateur Astrophotographer Magazine. But I wanted to see if I could improve on it.
I created a new entry for this version of the image since the original was published, I did not want to just replace it, I wanted to augment my portfolio by just adding a new imaging project entry.
The original project can be seen HERE. And the original image is show below for comparison:
The original image - for comparison.
About the Target
The following section is just a verbatim copy of the first post.
Messier 57, also known as the Ring Nebula or NGC 6720, is a planetary nebula located 2,500 light-years away in the constellation Lyra. Many sources credit the discovery of M57 to Antoine Darquier de Pellepoix , who found it while searching for the comet of 1779. In fact, he independently discovered it a few days after it was seen and logged Charles Messier, who added it to his now famous catalog.
Antoine Darquier de Pellepoix - November 1718– January 1802 (Image taken from Wikpedia)
This object is well known to amateur astronomers and is located just south of the bright star Vega, which forms one star of the Summer Triangle. M57 has a visual magnitude of 8.8 and is located about 40% between the bright stars Beta and Gamma Lyrae, making it very easy to find.
Planetary nebulas are formed when stars are in the last stages of becoming White Dwarfs and eject huge amounts of ionized gases that form an expanding shell that slowly grows with time. M57 has had its rate of expansion estimated to be about one arcsecond per century!
The Ring Nebula is very small, messing 1 x 1.4 arcminute, which means that the nebular disk cannot be easily resolved in a pair of binoculars - you will need a 3” telescope to see the disk and a 4” telescope to resolve the hole in the center. The central star is now very faint - at a magnitude of 15.8, so you will not likely see it visually unless a much larger scope is used.
The central region of the nebula is blue-green in color due to ionized oxygen. It glows red on the outer portion from the light of ionized hydrogen.
IC 1296
IC 1296 is the delightful little spiral galaxy seen just above M57 in the image above. I was very pleased with the detail I could capture on this little gem. While M57 is about 2,500 light-years from Earth, IC 1296 is a bit further afield - a whopping 240 Million light-years away! This galaxy is very small, subtending an angle of only 1.1 arcminutes. This would make the galaxy measure about 80,000 light-years across at its given distance.
This galaxy is classified as a barred spiral - type SBbc - and its two primary arms are joined to a bar that is 7 arcseconds in length.
It’s highly unusual to have a planetary nebula and a galaxy in the same field of view, making this paring stand out. Planetary nebulae are most often seen within the plane of the Milky Way as we look towards its core. So to see galaxies, we need to look away from the core - out to the deeps of space beyond the Milky Way.
The Annotated Image
This annotated image was created in Pixinsight, using the ImageSolver and Annotate Image Scripts.
The Location in the Sky
This finger chart was created in Pixinsight using the FinderChart process.
About the Project
This project took the same data and - in general - followed the same processing flow that was documented in the first work. So what changed?
Three things mainly:
BlurXTerminator was used to handle the deconvolution operations.
I used a starless workflow using the StarXTerminator
I made some different process adjustments along the way.
Image Processing
Normally, I would provide a detailed processing walkthrough.
But my basic flow was the same, and even very similar masks were used along the way. So I would direct you to look at the original post’s processing details, as most still are valid for this image.
Instead of traditional deconvolution methods, I used BXT to process the RGB color image, the Lum Image, and the Ha image.
Once I went nonlinear, I also went starless.
I processed the RGB first, then the Lum, and then the Ha.
I then folded the Lum image into the RGB image. Then I applied a mask covering the area of the Ha image to the RGB image that then folded the Ha image in using PixelMath.
At that point, I added the stars using a screening equation with PixelMath.
The image was cropped tighter than the first image.
Of course, along the way, I created many masks and tweaked the component images with CT and other tools. This time around, I made some different processing choices here as well.
Final Results
I should start by saying I was pretty happy with my initial results! I worked hard to pull out the details I could and was proud of the result.
I think the new version is better in serval ways:
The image scale is larger, and I think that works better here.
I think I brought more detail in the Ha outer gas shell
The overall detail is improved
The stars are better controlled for size.
The results are not as dramatic as they were for my last reprocessing project - which was M27. But I think the improvement worked well with this image.
More Information
Wikipedia: Messier 57
Nasa.gov - The Hubble Messier Catalog: Messier 57
messier.objects.com: Messier 57
The.Skylive.Com IC 1296
Cambridge-Photographic-Atlas-of-Galaxies: IC 1296
Capture Details
Lights Frames
Data was collected over five nights: July 28,-July 31, and Aug 2.
73 x 90 seconds, bin 1x1 @ -15C, Gain Zero, ZWO Gen II Lum filter
98 x 90 seconds, bin 1x1 @ -15C, Gain Zero, ZWO Gen II Red filter
101 x 90 seconds, bin 1x1 @ -15C, Gain Zero, ZWO Gen II Green filter
102x 90 seconds, bin 1x1 @ -15C, Gain Zero, ZWO Gen II Blue filter
63x 300 seconds, bun 1x1, @ -15C, Gain Zero, Astronomiks 6mm Ha filter
Total of 14.7 hours
Cal Frames
25 Darks at 90 seconds, bin 1x1, -15C, gain Zero
25 Darks at 300 seconds, bin 1x1, -15C, gain Zero
12 Flats at bin 1x1, -15C, gain Zero - for LHaRGB filters.
25 Dark Flats at Flat exposure times, bin 1x1, -15C, gain unity
Software
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…..
Capture Hardware:
Scope: Astro-Physics 130mm F/8.35 Starfire APO
built in 2003
Guide Scope: Televue TV76 F/6.3 480mm APO Dublet
Main Fous: Pegasus Astro Focus Cube 2
Guide Fous: Pegasus Astro Focus Cube 2
Mount: IOptron CEM60 - new
Tripod: IOptron Tri-Pier with column extension
Main Camera: ZWO ASI2600MM-Pro
Filter Wheel: ZWO EFW 7x36
Filters: ZWO 36mm Gen II LRGB filters
Astronomiks 36mm 6nm Ha, OIII, & SII filters
Rotator: Pegasus Astro Falcon Camera Rotator
Guide Camera: ZWO ASI290MM-Mini
Power Dist: Pegasus Astro Pocket Powerbox
USB Dist: Startech 7 slot USB 3.0 Hub
Software:
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…..
Adding the next generation ZWO ASI2600MM-Pro camera and ZWO EFW 7x36 II EFW to the platform…