M17 - The Omega nebula Astrophotography - 100-hour Mosaic
Updated: Sep 15
M17 is a fairly bright diffuse emission nebula, and is also commonly named the Swan nebula. M17 is very similar to the famous Orion nebula (M42), but it is seen from its edge, while M42 is seen face-on. Messier 17 is also about three to four times farther than the Orion nebula.
Object Designation: M17
Also known as: Omega Nebula, Swan Nebula, Checkmark Nebula, Lobster Nebula, Horseshoe Nebula
Constellation: Sagittarius
Object Type: Emission Nebula
Distance: 5,500 light-years away
Magnitude: 6.0
Discovery: October 18, 1745 by Philippe Loys de Chéseaux
In Astrophotography, getting the bright part of M17 is an easy feat, but if you would like to get some of the faint outer gases, make sure to spend some more time on gathering enough light. You will also want to keep those fainter gases in mind during your entire processing workflow, so you don’t accidentally make your image too dark and lose the data from the gases all around.
M17 Mosaic Astrophotography - 100 Hours in HO
June 2025 - September 2026
After shooting the Jellyfish Nebula for 100 hours and enjoying wrapping it up, I wanted to continue to work on such large projects and kept shooting M17 until also reaching 100 hours.
I shot this with my SVX130 rig from Starfront Observatories in the middle of Texas. It of course helps to have a remote telescope when starting long projects like this one!
Since I am working on several long images at the same time, this one took me more than a full year to complete!
I chose to do a mosaic (2 panels) because I wanted to include the very faint Oxygen III sprites visible near M17.
These are very difficult to capture, as only an OIII filter will reveal them and long exposure times. I am overall happy with the full mosaic image. Each panel took 50 hours to complete. I also had to discard my RGB stars because of a mistake I made, so the stars are in narrowband which is fine. It is a nice overall composition and I don't regret doing the mosaic!
Click the image to see it in full resolution!
Learn how to process your data like this with our PixInsight processing guides.
GEAR USED:
Camera: QHY600M
Telescope: Stellarvue SVX130
Mount: 10Micron GM1000 HPS
Accessories: Moonlite Nitecrawler focuser / Pegasus Astro Ultimate Powerbox
Processing: Pixinsight with RC-Astro plugins, final touches in Skylum Luminar Neo
ACQUISITION DETAILS:
Total Exposure Time: 100 hours
Exposure Time per frame: 10 minutes
Filters: Chroma 3nm H/O
Gain: 56
The Omega Nebula Astrophotography from Home with the L-Ultimate Filter
September 2022
Shortly after imaging M17 with Vespera, it was time to attempt it again but this time back with our regular astrophotography setup. We used a 75mm telescope and full frame color camera, once again from our backyard, but this time with the Optolong L-Ultimate narrowband filter.
The total exposure time for this image was just 2 and a half hours, as the target went behind the neighbor's trees pretty early. The filter did a great job at blocking unwanted light pollution, including the bright moon that was in the sky while imaging this!
Want to process your images following our own workflow? Get our PixInsight Guide!
Camera: QHY600C
Telescope: Radian 75
Mount: ZWO AM5
Guiding: ZWO ASI 290MM Mini
Accessories: Pegasus Astro Pocket Powerbox
Power: Jackery Lithium Battery
Processing: Pixinsight
ACQUISITION DETAILS:
Total Exposure Time: 2.5 hours
Exposure Time per frame: 10 minutes
Filters: Optolong L-Ultimate
Gain: 26
We made a video where we used the Optolong L-Ultimate filter on several nebulae, be sure to watch it below! In the video, we analyze the data we get and see if the filter produces any unwanted artifacts in the image, for example, star halos or reflections. We also have a written review about the L-Ultimate filter.
The Omega Nebula Astrophotography with the Smart Telescope Vespera
September 2022
In the Summer of 2022, we decided to try shooting the Omega Nebula with an All-in-One smart telescope known as Vespera.
Vespera is the second telescope by Vaonis after Stellina, which we reviewed in depth here. For this shot, we spent just one and a half hours imaging M17 from the backyard. Because of the light pollution, we used a narrowband filter, which easily attaches to Vespera's lens.
We then transferred the raw TIFF file onto our computer and processed it using PixInsight. We are very impressed with the image we were able to get, especially with just an hour and a half of exposure time! The nebula looks great, full of details, and with natural colors.
The Omega Nebula Astrophotography with a Newtonian Telescope and Triad Ultra
May 2020
We will show you our attempt at imaging this object from our light-polluted backyard using our $499 reflector telescope, a cooled astrophotography-dedicated camera and the TRIAD Ultra filter (click the link to read our review).
The TRIAD Ultra is a quad-band narrowband filter that allows you to image any narrowband target, no matter the light pollution. As a proof, our backyard is from a white zone, in a Bortle 9 scale. This is as light polluted as it gets.
We have a full review article and video about this filter on our website and YouTube where we image both NGC 1499 and Messier 42 (the Orion Nebula). Make sure to check them out!
Here is our final (or maybe not) image of the Omega Nebula. We may or may not add more hours to it in the near future.
Messier 17 using the TRIAD Ultra filter with the QHY128C
GEAR USED:
Camera: QHYCCD 128C
Telescope: 8" Newtonian
Guiding: ZWO ASI 290MM Mini
Processing: Pixinsight
ACQUISITION DETAILS:
Total Exposure Time: 5 hours and 40 minutes
Exposure Time per frame: 3 minutes
Filters: TRIAD Ultra Quad-Band
Gain: 3200
You can get our Raw files for dozens of target from many different setups with the Raw Data Pack :)
How to find the Omega Nebula?
Messier 17 is best seen through wide telescopes and binoculars. Only people with very good vision will be able to spot it with the naked eye under a dark site.
The Omega nebula is located in the constellation Sagittarius, near the Eagle Nebula. You can find it easily by spotting the bottom star of the constellation Scutum, or also by using the teapot stars in Sagittarius.
If using binoculars when trying to find it, make sure not to mistake the Omega Nebula with the Eagle Nebula, the Trifid or Lagoon nebulae, because they are all close to each other.
Cool Facts about the Omega Nebula
Discovered in 1745
One of the brightest star-forming nebulae
Home to 800 stars
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Processing Messier 17
Processing the Omega Nebula was no easy feat. I struggled a lot with several problems. First, my flats were outdated, and so I had to battle gradients and vigneting before I even started processing the image properly. Luckily, several iterations of the GradientCorrection tool in PixInsight helped take care of most of the problems.
Then, my RGB stars were completely out of whack. I had taken them first, several months before starting the OIII and HA shooting. The problem is that back then, my camera was rotated in a different way! I had completely forgotten about that, and the stars would not cover the entire field of view. To avoid faking the image with stars that I would have to pull out of my a**, I decided to keep the narrowband stars and learn my lesson. I never rotate the camera anymore now unless absolutely necessary, and only if I know my long projects are all done.
Lastly, there was the choice between doing an image that looks "true color" like my IC443, or one that looks like a Hubble Palette style. I chose to go with the Hubble style this time using the following formula in PixelMath:
R: H
G: (0.5*H)+(0.5*O)
B: O
Below you can see what a true color style would have looked like! I'll likely reprocess it like it someday for fun.
Make sure you take a look at the Galactic Course processing guides to learn how to process any type of targets to the best of your abilities!
What did each channel look like?
You may be wondering how the HA and the OIII looked before being combined into one color image. Below you can see the Masters for each!
The blue OIII sprites become much more visible when the stars are removed.
IC 443 FAQ
In which constellation is M17 located?
You can find the Omega Nebula (AKA the Swan Nebula) in the constellation Sagittarius.
How big is M17?
The Omega Nebula spans about 15 light-years in diameter (its brightest region). From Earth, it has an apparent size of roughly 20 × 15 arc minutes (sometimes listed as ~11 arc minutes for the core).
How old is the Omega Nebula?
The star cluster within M17 is one of the youngest known, with an age of about 1 million years.
How far is M17?
The Omega Nebula is about 5,500 light-years away from Earth
How long should my exposure times be when photographing M17?
This is a bright emission nebula with plenty of details, but also a lot of faint outer regions. I would suggest doing 600-second exposures, or longer if you can. If you're afraid your core will be too bright in the end, you can also do some 180-sec exposures, but HDRMultiscaleTransform helps reduce the brightness in the core pretty well.
Should I use a filter to image the Omega Nebula?
Yes. M17 is a good narrowband/duoband target. Ha and OIII dominate, so a dual-band filter or separate Ha + OIII works very well. SII is present but weaker, so include it if you want a full SHO palette. RGB (or broadband) is still useful for the stars. If you want the Blue Sprites, be sure to shoot for a long time in OIII.
Final Thoughts
I like the 100-hour mosaic I captured of this target, especially since it includes the blue sprites, which is what I wanted to most! I have other 100-hour projects in the works, and I'll be doing mostly that from now on (and yes I know it's useless to do more than 20ish-50 max hours), but I like it, ok?
If you would like to learn how I process all my images, you can get my PixInsight processing workflow for the type of target of your choice HERE. It includes text lessons, tutorial videos, our custom process icons, raw data, and more! The course is updated whenever I decide to tweak my workflow or add more to it, and you always get the updates for free!
Have you captured the Omega Nebula? Attach your image in the comments and let us know what you used!
Clear Skies,
Galactic Hunter
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