M42 The Great Orion Nebula

M42 The Great Orion Nebula

4-Panel Mosaic

Constellation: Orion
Ra: 05h 35m 17s
Dec: -05d 23m 30s
Distance: 1,400 light years
Image Size: 54' x 54'
North: Up; East left



The Great Orion Nebula (Messier 42, NGC 1970) in the constellation of Orion is the closest region of massive star formation to earth, and is so bright that is is visible to the naked eye. It is south of the three easily recognizable belt stars, and is the middle of the three sword stars that is clearly “fuzzy” in appearance, especially using binoculars. The nebula is 24 light years across and is estimated to contain the mass of 2,000 suns. Orion has a young open cluster at its brightest part containing 4 obvious stars referred to as the Trapezium, of which two are visual double stars, making a total of six. The coloration of Orion is an interplay of magenta coming from ionized hydrogen (red H-alpha and some blue H-beta), and blue/green or teal from doubly ionized oxygen (OIII). This coloration and detail was brought out from many long exposures using H-a and OIII narrowband filters. The nebula is part of a much larger complex known as the Orion Molecular Cloud Complex, which includes familiar astrophotography objects, such as Barnard’s Loop, M43 (shown in the above image as the tear-shaped object just north of the Trapezium), the Horsehead Nebula, M78 and the Flame Nebula. The Hubble Space Telescope found over 100 areas where planetary systems are forming around young stars, so the Orion Nebula is clearly a star and planet nursery.

This is a joint project with my observatory partner, Josep Drudis, on my PlaneWave CDK20 (0.5m) telescope located at the iTelescope.net facility at Siding Spring, NSW, Australia. It incorporates nearly 55 hours of exposures and required repeating the data acquisition in four overlapping frames in order to cover the 60 – 80 arcmin size of the Orion nebula. We ended up with slightly different versions on our respective web sites due to our different artistic interpretations of this complex object.

As a personal note, I have been doing astrophotography for about 17 years. The Orion nebula is always one of the top 3 or so most popular objects to image, along with the Horsehead, North American and Ring Nebulae. It has everything. It has structure. It has vibrant colors. It is large and therefore suitable for smaller telescopes that beginners start out with. That being said, it is absolutely the most difficult image that I have ever processed due to the huge dynamic range from the very bright Trapezium to the faint, less ionized, cloudy regions at the extremities. You then need to blend short and long exposures, similar to an HDR (high dynamic range) process for a DSLR camera. This is not my first attempt, but I am pleased that it exhibits what I feel is a good balance among structure, color and dynamic range. I do not generally editorialize when I post my images, but Orion is a special case. So if you are just starting out and cannot wait to image Orion, well, caveat emptor. My sympathies and hopes are with you.

Exposure: 54.75 hrs Total; 42 hrs H-a and OIII, 12.75 hrs RGB
Telescope: PlaneWave CDK20, 0.5 m f/6.8 0.54 arcsec/pix
Mount: PlaneWave Ascension 200h
Oag: Astrodon MonsterMOAG
Acquisition: ACP-Expert
Calibration: CCDStack2
Observatory Site: iTelescope, Siding Spring, NSW, Australia
Camera: SBIG STX 16803
Filters: Astrodon 5nm H-a, 3nm OIII, Gen 2 RGB
Guider: Starlight Xpress Lodestar
Camera Operation: Maxim 5.24
Processing: Photoshop CC 2019
Image Date: 02/04/2018 - 08/01/2018

1 Comment

  1. Sakib

    David Malin would be proud, you’ve done really well! I love the sense of wispy smoke like a wildfire in the forests of Nevada. It is probably easier to image something faint like Patchick 161.


Submit a Comment

Your email address will not be published. Required fields are marked *

The reCAPTCHA verification period has expired. Please reload the page.