The Omega Nebula – Summer Deep Sky Astrophotography Target
The Omega Nebula is one of the many satisfying deep sky astrophotography targets located in Sagittarius. M17 (Also called the Swan Nebula) is a brilliant H II region nebula between 5000-6000 light years from Earth.
I captured this image using a Canon DSLR and a small refractor telescope from my suburban backyard in Ontario, Canada. A UV/IR filter was in my Canon T3i/600D to help ignore the unwanted city light pollution.
This image was the subject of my review of the SkyTech CLS-CCD light pollution filter. The UV/IR block element of this particular filter keeps stars small and prevents bloating. I later combined data acquired using a stock Canon DSLR for a more accurate background sky and star color.
The complete photography details for this image including the list of equipment used are listed below.
M17 – The Omega Nebula
Also known as the Swan Nebula
This nebula includes an H II region where star formation has recently taken place. The Omega Nebula rises high enough from my latitude to start imaging in early April if you’re up late enough. It’s always exciting to see M17 for the first time in the year, as it marks the beginning of Milky Way season for stargazers.
In late May of 2017, I set up my Explore Scientific ED102 telescope on the far side of my backyard for a low view of the South Eastern horizon. The Omega Nebula rises higher than some of my other favorite targets in Sagittarius such as the Lagoon Nebula.
The night of this astrophotography session was clear yet hazy. I think that the transparency of the air affected the quality of my stars in the image. Regardless, I am delighted to photograph such an incredible nebula from the comfort of my backyard.
UV/IR Camera Filter
My Canon 600D DSLR has been modified for astrophotography, known as a “full spectrum modification”. This process opens the CMOS sensor of the Canon T3i to all wavelengths of light, including the bright reds found in emission nebulae such as the Omega Nebula.
When a modified DSLR is used with a refractor telescope or camera lens, it is essential to use a UV camera filter or an IR filter. The SkyTech CLS-CCD filter was used on my Canon DSLR for the astrophoto above.
This filter also improves the contrast between the astronomical object and the background sky. Filters such as the CLS-CCD are a great option for backyard astrophotographers looking to block out light pollution, without sacrificing any of the “good” light.
Bottom Line: An IR filter blocks wavelengths of infrared light that do not focus at the same point as visible light.
View through a 102mm Refractor
The version of M17 below is a wide field view through my 102mm refractor. This should give you a good indication of the scale you can expect with similar equipment.
This photo shows some of the odd gradients in the background sky due to my imaging conditions. Collecting more light in favorable conditions would help correct this. I’d also like to add some H-alpha data to my photo for an HaRGB composite.
My final image includes 30 individual images of 3 minutes each, using ISO 800. I used BackyardEOS for camera control, as I am still learning how to run the camera using Astro Photography Tool.
The nights are very short this time of year, with daylight beginning to show itself in my image subs by4am. This short imaging window creates a sense of urgency to get up and running as fast as possible.
Image Processing Notes
The stars got a little “chewed” in the processing, something I have been trying to be aware of lately. I have a habit of focusing on the detail of the nebula while turning a blind eye to the surrounding space and stars.
To be honest, 90 minutes is not nearly enough to really start processing a deep sky image. Add the poor imaging conditions, and a hot night, and you’ve got a challenging task of stretching and smoothing your data in Photoshop.
I was starting to get used to the cooled sensor of the ASI071MC-Cool, and now completely see the obvious benefits over a regular CMOS sensor. This camera has been returned to Ontario Telescope and Accessories, so I am again focusing on maximizing my results using the Canon 600D.
Astrophotography Image: The Omega Nebula
Photographed on: May 27, 2017
Telescope: Explore Scientific ED102 CF
Mount: Skywatcher HEQ-5 Pro
Guide Camera: Altair GPCAM2 AR0130 Mono
Guide Scope: Altair Starwave 50mm
Camera: Canon Rebel 600D (modified)
Total Exposure: 1 Hour, 30 Minutes (30 x 180 seconds)
Processing Software: Deep Sky Stacker, Photoshop CC
Support Files: 20 darks, 20 flats, 20 bias
Guided with PHD Guiding
Stacked in Deep Sky Stacker
Processed in Adobe Photoshop CC