The Orion Nebula, also known as M42, is a a star factory. Located 1400 light-years from Earth, it’s the closest region of intense star formation to us.
Askar 130PHQ: March 2023
This was a really tricky target for a number of reasons. First, the nebula is only during a narrow window of opportunity from my garden, as it passes my house’s chimney but before it reaches the shed roof. That’s a few hours at most per night. Also, the weather was awful and I was clouded out almost all the time. Then worst of all, my camera fan broke! I had to order a new fan and then install it before I could continue. All in all, a bit of a disastrous six weeks.
Despite that, I managed just over 11 hours using my Optolong L-Ultimate. I then collected almost two hours of RGB data (by simply removing the filter). My plan was to use this RGB data just for the stars. However, I found that despite the short integration time, M43 — the smaller nebula to the right of the image — showed up well. This is probably due to the fact that it’s part reflection nebula, so shows up better in broadband wavelengths compared to the larger hydrogen-rich M42 nebula that dominates the picture. So, I followed a simple tutorial and combined my L-Ultimate and RGB data into a single image. I was happy with how well that turned out.
As for the stars, I just couldn’t get them looking as good in RGB as the L-Ultimate data. I even tried shooting shorter subframes for RGB — 30 seconds, instead of my standard 120 — but it didn’t seem to make any noticeable difference overall. So, the stars are actually from the L-Ultimate data. There wasn’t much colour in the RGB version, so no big loss there.
The Orion Nebula is notoriously difficult to process and in the end I spent the best part of two days playing about with different techniques and settings. The bright core in particular often causes people issues as it’s so bright compared to the rest of the nebula. To overcome this, I took the image into Adobe Lightroom fairly early in my processing and tamed the highlights to return detail to the core. The Trapezium stars are even visible, if you look closely. Much simpler than taking different exposures!
While writing this up, I’ve realised it’s almost exactly two years since I took my previous Orion Nebula photo. More details below, but here’s a quick slider comparison. Good progression I reckon!
Imaging details
* January – March 2023 (six weeks)
* Bristol, UK (Bortle 8)
* Telescope: Askar 130PHQ Flatfield Astrograph
* Camera: ZWO ASI 2600MC-PRO
* Mount: Sky-Watcher EQ6-R PRO
* Guide: William Optics 50mm Guidescope with 1.25″ RotoLock; ZWO ASI 120MM Mini
* Control: ASIAIR Plus
* Software: PixInsight, Lightroom
* Filters:
– Optolong L-Ultimate (Ha / OIII): 337 x 120 seconds (11 hours 14 mins)
– No filter: 212 x 30 seconds (1 hour 46 mins)
Total exposure time: 13 hours
By Lee Pullen
Example source data
Askar FRA400: February 2021
The Orion Nebula is one of the best targets for astroimagers in the northern hemisphere. It’s big and bright, and also shines brighly in hydrogen wavelenghts; put that all together and it’s an ideal target for city imagers with a dual-band filter like the L-eXtreme.
Because of these reasons, I chose it for one of the first imaging runs with my new kit. Getting the timing right was a challenge because the Orion Nebula’s path in the sky takes it behind the chimney on my roof! So it was difficult to get long imaging sessions. This was also before I embraced aiming for long integration times. Plus I was new to editing in PixInsight. Despite all these hurdles, the end result is passable. Roll on next Winter, when I’ll start from scratch and aim for a better result.
* February 2021
* Bristol, UK (Bortle 8)
* Telescope: Askar FRA400 f/5.6 Quintuplet APO Astrograph
* Camera: ZWO ASI 2600MC-PRO
* Filter: Optolong L-eXtreme
* Mount: Orion Sirius EQ-G
* Guide: William Optics 32mm; ZWO ASI 120MM Mini
* Control: ASIAIR PRO
* Software: PixInsight and Lightroom
* 89 x 300 seconds
Total integration time: 7 hours 25 minutes
By Lee Pullen
Example source data
Astrophotography is a pricey hobby, please help me out!
Spectacular as always Lee! Let me buy you a beer just for sharing this art!
Thanks for the donation!