Two clear Sundays in a row ...
Orion is one of the most popular constellations for astrophotography. With showpiece objects like the Orion Nebula and the Horsehead Nebula, you can’t go wrong pointing your telescope there on the few clear winter nights we get. Sunday, March 1st was forecast to be clear, so I slewed my telescope to the central spine of the Orion Molecular Cloud Complex — framing the Horsehead/Flame region and the Orion Nebula (M42/M43), with the Belt stars Alnitak and Alnilam anchoring the field.
The Moon was nearly full that night, so I used my Optolong L‑eXtreme filter to tame the bright sky. The following Sunday, March 8th, was also clear, but this time the Moon didn’t rise until after midnight. That gave me a chance to capture the field in broadband RGB with no filter. The final image is a composite of the RGB data from March 8th and the Hα extracted from the dual‑narrowband data from March 1st.
Image 1: RGB + Ha image of the central spine of the Orion molecular Cloud Complex
 |
| RGB + Ha image of the central spine of the Orion Molecular Cloud Complex captured from my backyard on 3/1/2026 & 3/8/2026. |
What is it?
This field captures the central spine of the Orion Molecular Cloud Complex, one of the richest and most active star‑forming regions in the night sky. The combination of bright emission nebulae, dark dust clouds, reflection nebulae, and massive blue stars makes this area a favorite for both astrophotographers and professional astronomers.
Image 2: Annotated image
 |
| An annotated version of the image. |
Prominent Objects in the Field
Horsehead Nebula (B33) - The Horsehead Nebula, also known as Barnard 33, is a dark nebula silhouetted against the red glow of the emission nebula IC 434. Its dense dust cloud blocks the background light, creating the distinctive horse‑head shape that makes it one of the most recognizable objects in the night sky.
Flame Nebula (NGC 2024) - The Flame Nebula is an emission nebula next to the leftmost star in Orion’s Belt, Alnitak. Dark dust lanes cut through the bright emission region, and smaller branches of dust radiate outward, enhancing its resemblance to a flickering flame.
Orion Nebula (M42) & De Mairan's Nebula (M43) - M42 is arguably the most popular target for amateur astronomers (both visual and astrophotography). This area is a bright H II region and an active stellar nursery. M42 is a massive star forming region and is (astronomically speaking) relatively close to the Earth. M43 is just north of M42. M42 and M43 are separated by a dark dust lane.
Running Man Nebula (Sh 2‑279) – The Running Man is a combination of emission and reflection nebulae located just north of M42 and M43. Bright blue starlight reflects off surrounding dust while faint H II emission fills the background, creating the distinctive “running” silhouette that gives the nebula its name.
Alnitak and Alnilam - Alnitak is the leftmost star and Alnilam is the middle star in Orion's belt. Both stars are bright Type O/B stars.
How big is it?
For reference, the Moon has an apparent size of 31 arcminutes.
Horsehead Nebula (B33) - The Horsehead Nebula has an apparent size of 6 x 4 arcminutes on the sky with an actual diameter of 2.8 light-years (ly).
Flame Nebula (NGC 2024) - The Flame Nebula has an apparent size of 30 x 30 arcminutes on the sky with an actual diameter of 7.1 ly.
Orion Nebula (M42) & De Mairan's Nebula (M43) - M42 has an apparent size of 85 x 65 arcminutes on the sky with an actual diameter of 34.7 ly. M43 has an apparent size of 20 x 15 arcminutes on the sky with an actual diameter of 10.2 ly.
Running Man Nebula (Sh 2-279) - The Running Man Nebula has an apparent size of 40 x 25 arcminutes on the sky with an actual diameter of about 15 ly.
How far is it?
Distance estimates for the Nebulae in this image range from 1,260 to 1,600 ly from Earth.
Alnitak is about 740 ly and Alnilam is about 2,000 ly from Earth.
How to find it?
Refer to the red rectangle in the finder chart below.
Let's start with the easiest objects to find, Alnitak and Alnilam. Alnitak is the leftmost star and Alnilam is the middle star in Orion's Belt. Both Stars are visible with just your eyes, and can be seen from just about anywhere.
Just below Orion's belt are three stars (maybe 2 depending on light pollution and sky conditions) known as His Sword. M42 is the middle "star" in the sword. Visible to the naked eye (light pollution and sky conditions depending) as a fuzzy star. Easily observed in binoculars and telescopes.
The Horsehead is "easy" to find but very difficult to actually see (visually). Think of trying to see a black smudge on a black tablecloth. Although it is difficult to visually observe, it is relatively easy to image. To visually observe the Horsehead Nebula, a 10" or larger telescope, H-beta filter, and dark skies are required. The Horsehead is located about 1 degree south of the bright star Alnitak (the leftmost star in Orion's belt).
Image 3: Finder Chart
 |
| Finder chart for the field. |
Processing:
My goal with this image was to preserve natural star colors from the RGB data while using Hα to enhance the emission structures in IC 434, the Flame Nebula, and the extended nebulosity around M42. The workflow below reflects that balance.
Narrowband Workflow:
Linear Processing:
- Gradient removed with MSG.
- The narrowband image was aligned to the RGB image with Star Alignment.
- The registered image was cropped using Dynamic Crop and the instance of the process was saved to the desktop so it could be used to duplicate the crop on the RGB image.
- BlurXTerminator was used for deconvolution
- The stars were removed with StarXTerminator. (The narrowband stars were not saved)
- Noise was reduced with NoiseXTerminator.
- The image was made non-linear with Generalized Hyperbolic Stretch.
Non-linear processing:
- The image was separated into the R, G, & B channels using Channel Extraction.
- The R image was used as the Ha image and the B & G (Oiii) images were discarded.
RGB Workflow:
Linear Processing:
- Gradient was removed with MSG.
- The image was cropped to duplicate the narrowband images with the saved instance of Dynamic Crop.
- BlurXTerminator was performed in correct only mode.
- Color calibration was performed with SPCC.
- BlurXterminator was used for deconvolution.
- The stars were removed (and saved) with StarXTerminator.
Starless linear processing:
- The image was made non-linear with Generalized Hyperbolic Stretch.
Starless non-linear processing:
- The toolbox CombineHawithRGB script was used to blend the Ha into the RGB image.
- I used the CreateHDRImage script to tone down the core of the Orion Nebula.
- Image blend was used for sharpening by using the high pass filter.
- CT was used to enhance color and color saturation.
Star Processing:
- Stars were stretched with Seti Astro's Star Stretch script.
- CT was used to enhance color and saturation.
Final Blend
- The stars were screened back into the starless image with PixelMath.
No comments:
Post a Comment