Background

I almost captured the Cygnus Wall in an earlier image of the Pelican Nebula, taken with my previous Askar FRA400 telescope. Part of my wanting to upgrade to my new Askar 130PHQ was to really focus in on parts of large nebulae, seeing details that are hard to get with a small-aperture wide-field telescope. So I was drawn to the Cygnus Wall because I knew it was a dynamic part of the night sky, and would fill my focal length of 1000mm very nicely.

The nights are starting to draw in and there was a spell of decent clear weather, which meant it only took me three weeks to collect 40 hours of data in total. 18 hours was Optolong L-Ultimate data. This looked fairly clean after integrating, which is always a good sign! The positive omens continued when I integrated 19 hours of Askar D2 data. This often looks quite a bit worse than the L-Ultimate, as it’s capturing sulphur-II (SII) instead of Hydrogen-alpha, and the signal is usually weaker. Although it was a bit noisy, I was happy to see a decent level of detail. And finally, I captured three hours of RGB (no filter) data. My plan was to just use this for true colour stars, but the nebulosity looked too good to chuck and I ended up including it in the final image by using PixInsight’s NBRGBCombination utility. You can see example raw subframes and freshly integrated data if you scroll down to “Example source data”.

So, this image is actually a mix of S H O and RGB, all from an OSC camera. Pretty neat! It’s fair to say the result could have been obtained faster (and perhaps better) using a mono camera and filters, but the required kit is more expensive and data acquisition would have been a bit more fiddly. In any case, I think the end result is very respectable, especially considering my light-polluted city-centre location.

This image was used as the cover of the Winter 2023/24 issue of community magazine Up Our Street.