Messier 42 - The Great Orion Nebula
Date: Dec 23, 2019
Revised Feb 12, 2025
Cosgrove’s Cosmos Catalog ➤#0016
Awarded Flickr “Explore” Status!
Messier 42 - The Great Orion Nebula (click to enlarge)
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About the Target
Messier 42—The Orion Nebula, or the Great Orion Nebula, is one of the brightest and most beautiful nebulae in the night sky! Also known as NGC 1976, this diffuse nebula is located 1344 light-years away in the constellation of Orion.
This area of dust and gas is a stellar nursery, and new stars are continually being born there. While the Milky Way Galaxy has many star formation regions, M42 is one of the closest to Earth.
At magnitude 4.0, M42 is one of the brightest nebulae in the sky and can be seen by the naked eye.
It can be seen as a fuzzy region around the middle star, the sword that hangs from Orion’s Belt. Binoculars show even more nebulosity and even small telescopes show the nebula with a dark void often described as the “Fish's Mouth” and a bright star cluster at its core, known as the Trapezium.
This is a young open cluster of what appears to be four stars located in a bubble about 1.5 light years in diameter. Some of these stars can be resolved as double stars. This bright group of new stars illuminated the gas and dust in the area and maybe a sub-component of the larger Orion Nebula Cluster, a grouping of about 2,000 stars within a diameter of 20 light years.
Everybody that does astrophotography shoots this very famous object at some point or another. This is my very first shot at it.
The Annotated Image
An annotated image of the Horsehead and Flame Nebulae was created by using Pixinsight’s ImageSolver and AnnotateImage Scripts.
The Location in the Sky
IAU/Sky & Telescope Constellation Map of Orion - with M42 region marked by the yellow arrow.
About the Project
M42 is a very high-dynamic-range scene, and it is straightforward to saturate the brightest parts.
So, my strategy for this project was to use one series of subs to pull in the nebula, another series of subs with short exposures to capture the bright areas, and then blend them.
So I did 20 x 3-minute exposures of the main nebula and 20 x 2-second exposures of the Trapezium and brighter portions.
Processing was originally all done in Photoshop, and the two images were blended using a mask.
I was pretty happy with the original image I produced with this effort. It was evident that there was a lot of detail and structure. In fact, it was the very first image I made that I felt confident enough about to share with the local Astronomy Group.
I got a pretty good response when I shared the image.
However, my initial image seemed to have a lot of green tones to it. In general, there is not much green coloration in deep-sky objects unless they are some kind of planetary nebulas. But at the time, I did not know this. Below is my original image.
My original processing of M42. (Click to Zoom)
After I started using Pixinsight for image processing, I returned to my M42 data and completely reprocessed it, using the Photometric Color Calibration routine to set the color. The final result of that effort is the image that I used as the main one for this posting. I was very happy with this version of the image!
It was not until much later that I learned that M42 has a subtle green color caused by a double ionization process that occurs only with rarified gases. So, maybe my original is right.
Which do you like better?
More Information
Wikipedia: Messier 42
Wikipedia: Trapezium
NASA: M42 and Hubble Images
Capture Details
Light frames
30 x 180 seconds, bin 1x1 @ -15C, unity gain
20 X 2 seconds, bin 1x1, @-15C, unity gain
Total of 1.5 hours
Cal Frames
• 25 bias frames at 1 seconds, bin 1x1 @ -15C, unity gain
• 25 Darks 180 seconds, bin 1x1 @ -15C
• 25 Darks 2 seconds, bin 1x1 @ -15C
• 25 Flats
Capture Hardware
Scope: William Optics 132mm f/7 FLT APO Refractor
Focus Motor: Pegasus Astro Focus Cube 2 - new
Guide Scope: Apterna 60mm Guidescope - new
Mount: Ioptron CEM 60
Tripod: Ioptron Tri-Pier
Camera: ZWO ASI294MC-Pro
Guide Camera: ZWO ASI290MM-Mini
Dew Strips: Dew-Not Heater strips for Main and Guide Scopes - new
Power Dist: Pegasus Astro Pocket Powerbox - new
USB Dist: Startech 8 slot USB 3.0 Hub - new
Polar Alignment Camera: Polemaster
Software
Capture Software: PHD2 Guider, Sequence Generator Pro controller
Image Processing: Deepsky Stacker, Pixinsight, Photoshop - assisted by Coffee, extensive processing indecision and second-guessing, editor regret and much swearing….
