Messier 42 – Winter 20/21 Project

The first month of the new year can only be described as…drab. The weather in January has been one of constant cloud, wind, rain, snow and ice. Since my last post just before the end of last year, I can count on one hand the amount of clear nights that I have had! So I’ve been using them wisely and capturing some longer exposures of the M42, The Great Orion Nebula.

Ever since I started my journey into Astrophotography back in May, I’ve always wanted to capture this absolutely stunning deep space object. It’s been one of fascination ever since I was a child; I used to spend hours looking at pictures in astronomy books from the early 90’s. The images available at that time were probably either taken with the Hubble Space Telescope, or some of the large terrestrial telescopes in observatories on top of mountains. Definitely not someone in their back garden with a DSLR camera!

I’ve had two clear nights in the past month that I have been able to image M42, and only for an hour or two at most. I first managed to capture it on the 9th January, capturing eight, 100-second exposures. Not ideal! What also didn’t help matters was that the weather turned VERY hazy as M42 rose higher in the south, eventually dipping behind the apex of the house. That Saturday night was the first clear night after the first heavy snowfall of 2021, and so it was still very cold; so cold in fact that my telescope and camera had actually begun to ice up towards the end! Even so, I managed to stack the decent 6 frames together, and merge the new 10-minute stack with my previous image. The previous stack of 30-second exposures was used for the core of the nebula, which is incredibly difficult to get right, while the new 100-second stack was used for the rest of the nebula itself.

12 minutes of 30-Second exposures for the core.
10 minutes of 100-second exposures for the nebulosity.

The two image stacks were first aligned in photoshop and cropped to the same size. I separated them into two separate documents and edited them separately, finally recombining them and blending them together. By using the eraser tool on the brighter top layer, I was able to bring through the detail of the shorter 30-second exposure in the core.

If you pixel-peep into to the core, you can just about see the Trapezium Cluster at its centre, so I’m pleased that these are visible in the final image. They’re a little blown out, but I’m imaging only using a 650mm focal length telescope, not an EDGE HD! The focal length struggles to resolve the finer detail on stars that small. But even so, I’m please I caught them!

Orion Trapezium Cluster

In the first half of the month, M42 was only visible between the houses from around 8PM til 9PM, giving me a very short window to capture anything meaningful. However, nearly a fortnight had passed by the time the next clear night came around. Fortunately, the nebula was now visible on the other side the house, this time for more than a couple of hours. This meant me setting up my mount in my old spot in the middle of the patio again. Polar aligning is now a cinch as well, thanks to a polar reticule light that I had for Christmas. My back doesn’t hurt now from having to keep swapping hands while holding my head torch to illuminate the polar reticule. Everything was aligned using both hands and sat comfortably underneath the mount. 2-minutes. Done.

Sky-Watcher Polar Scope Illuminator

For once, everything seemed to be going to plan, even my guiding was behaving for a change…after a few re-calibrations along the way that is. But eventually it sat very comfortably around the 0.8″ RMS error, which is the best it’s been for a long while. Even dithering went according to plan and was recovering and guiding again within 30 seconds, instead of dragging on for two minutes. I even had to reduce my minimum settle time as it was taking too long to start the next exposure!

PHD2 Guiding

The weather was still cold, being the middle of January, but no ice was forming on my telescope this time around. Also the 56% moon didn’t help matters; I tried to shield my scope as much as I can, but it still reduced the amount of detail that I was able to capture. It’s actually quite shocking how much the moon can affect the overall sky brightness. Not good for when you’re taking 5-minute exposures, as it’s very easy to over expose a shot with all the extra light pollution. Therefore, I had to keep an eye on my image histogram to make sure that everything was being exposed correctly, other than the nebula core which was completely blown out.

All-in-all, I managed to finally capture a decent amount of exposure, with 25 frames taken at 300-seconds long. However, due to passing cloud and the odd strong gust of wind, I only managed to stack 13 frames, thus giving me a total of 65 minutes.

A single exposure taken with N.I.N.A.

Again, I layered the new image on top of the previous combination, erasing the central core and the surrounding area to reveal the detail lost in the overexposed frames. With the much longer exposure for the surrounding nebula, the amount of detail that I was able to bring out was outstanding when compared with the previous version. The nebula in this new version is much brighter, and the final histogram was more balanced when compared with previous versions.

M42 – The Great Orion Nebula – 30s/100s/300s Combination

The stars at the bottom of the frame do have some halos around them, probably from a reflection between the Baader MPCC and the IDAS NGS1 filter that’s attached to it. Honestly though, I think it adds to the final result, making it look more ‘natural’ and not overly Photoshopped. I tried to not over processes the black levels too, as the whole area around the nebula is full of dark dust lanes. More exposure might help bring out the darkest of the dust, but I might have to leave that for another day later on in the year if these clouds keep insisting on sticking around. I am over the moon with the final result though, and I’ll hang up this project and call it completed…for now.


Well, I’ve started the year as I mean to go on! I mentioned in my previous post that I wanted to do ‘projects’ rather than one-off nightly images. It wasn’t the total amount of exposure that I wanted to achieve, but it’s a start. The final result is an image that I am most proud of when compared with everything that I have accomplished in the past year, and I aim to continue in that same manner. This year I want to take what I accomplished in 2020, and run with it. Let’s see where it leads!

Till next time, wherever you are, I wish you clear skies!

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