High-Resolution Wide-Field image of Orion

The constellation Orion is one of the most interesting regions of the sky.  Viewing all of it, in a wide-field, high resolution image, reveals its many wonders.  

Orion is one of the most obvious and recognizable constellations in the sky.  Even young children point up to the sky and say “look, there’s Orion”!

Orion is named after the hunter in Greek mythology. His shoulders are the red supergiant Betelgeuse (Alpha Orionis) and Bellatrix (gamma Orionis).  His foot and knee are the blue supergiant Rigel (Beta Orionis) and Saiph (Kappa Orionis), respectively.  His belt, perhaps one of the most notable asterisms, comprise Alnitak, Alnilam and Mintaka (which is a nice double star).  Figure 1 shows the mythological hunter fending off Taurus the bull.

Straddling the celestial equator, the winter hunter rises in the fall and sets in the spring, just in time to be relieved by the summer hunter, Hercules.  They essentially trade places every 6 months, with Hercules higher in the sky at its peak altitude.  

Orion is not just stars.  It contains a wealth of nebulae and star clusters.  The nebula types cover the full range, from dark, to reflection to emission.

I have always wanted to capture all of Orion, and in high detail, to reveal all the goodies within its boundaries.  I put it off for years, because I felt that to do it correctly would require many nights of imaging, capturing piece-by-piece, and then the daunting task of assembling it into a mosaic.

But recently, I decided to try to capture all (or most) of Orion in just two nights, without any mosaic.

To frame all of Orion with my existing astronomy camera, I need around 35mm focal length, with the camera oriented as Right Ascension left-right, and Declination top-bottom (portrait).

I owned a Canon 18-55mm lens, that I could set at 35mm FL, but that would have been f/4.5 wide open. Though that is “fast”, I wanted faster to get it in just two nights.

So, I purchased a very inexpensive Yongnuo 35mm, f/2 lens ($95).  See figure 2.

Figure 2: Yongnuo 35mm lens on Amazon.com

Combining that lens with my ZWO ASI 294MM, in BIN 1 mode, would produce a 5644 x 8288 (47 Megapixels) image. (Note, the final image was cropped to 5400 x 7400)

I did some testing when the lens arrived, and the star shapes were very poor wide-open.  So, I decided to collect the H-alpha narrowband wide open at f/2.0, remove the stars using Russel Croman’s AI StarXterminator, and capture all the R-G-B data at f/6.3, using that for the stars and reflection nebulae.

I could have used the stars from the f/2.0 data, thanks to another Russel Croman AI deconvolution program, “BlurXterminator”.  Figure 3 shows the corner stars from the f/2.0 data, before (left) and after (right) BlurXterminator.  I did not use the f/2.0 H-alpha stars in the final image.

Figure 3. Stars from upper right corner of image, from f/2.0 H-alpha data before (left) and after (right) BlurXterminator.

When the night of testing was complete, I spent another night using narrowband H-alpha, for the emission regions, and the next night using Red-Green-Blue filters for everything else.  The details of the capture are at the end of the article.

I calibrated, aligned, stacked and processed all the data in PixInsight.  The final result is shown in Figure 4, and Figure 5 is an annotated version, showing some of the many objects contained within. 

The full resolution image can be found here:   https://www.astrobin.com/vt80uh/BH/

Figure 4. Orion High-resolution, Wide-field, 4.4 hours of data, by Steven Bellavia

Image capture details:

Resolution: 5400×7400 (40 Mega-pixels)

Lens:  Yongnuo 35mm, f/2 lens for Canon EF

Astromechanics Canon ASCOM lens controller (for electronic focus, though auto-focus did not work well enough to use)

Camera: ZWO ASI 294MM

Integration (4.4 hours total):

  – 4.5nm H-alpha 20 x 4-min  at f/2

  – Red, 33 x 2-minutes  at f/6.3

  – Green 32 x 2-minutes  at f/6.3

  – Blue, 37 x 2-minutes  at f/6.3

Mount: Sky-Watcher EQ6-R Pro

Guidescope: Modified SvBony 30mm, 210mm FL, f/7.0

Guide Camera: ZWO ASI 224MC

Location: Southold NY

Dates and conditions:

   Feb, 03, 2024: Mostly cloudy until 9:30 PM, with a nice clearing. 2 to 7 Celsius, dry, some wind

   Feb 04, 2024: Clear all night, 2 to 7 Celsius, dry, very little wind. Sky darkness: 20.5 mag/sq-arcsecond


End of article



Steven Bellavia is an amateur astronomer and telescope maker.  He is an aerospace engineer who worked for Grumman Aerospace with the Thermodynamics Group of the Space Division. He had a key role in developing a nuclear rocket engine, and performed the analysis, design and fabrication of the micro-gravity liquid droplet radiator that flew on Space Shuttle mission STS-029. 

Steve has been at Brookhaven National Laboratory since 1992 and is the principal mechanical engineer for the camera on the Vera Rubin (formerly called the Large Synoptic Survey Telescope, LSST).  Prior to that, he was doing research and engineering for the Relativistic Heavy Ion Collider and the NASA Space Radiation Laboratory.

Steve has been recognized for the discovery of the Clair Obscure effect “Lunar L”, which is described in the December 2018 issue of Astronomy magazine.

Steve is an assistant adjunct professor of astronomy and physics at Suffolk County Community College and the Astronomy Education and Outreach Coordinator at the Custer Institute and Observatory in Southold, New York.