Finally, some more clear nights with an almost moonless night. After my last successful outing on the Pinwheel Galaxy at the end of April, I was keen to complete at least one more LRGB image before we lose astronomical darkness for the summer. I attempted Iris Nebula last summer but a lack of ability along with inclement weather meant I failed badly on it. It is still early in the season for this nebula as it remains low in the north eastern skies, however this allowed me to complete 3 clear runs without meridian flipping so it was worth the gamble.
I imaged over three nights, gathering 6 hours of luminance and 3 hours total of RGB data. The exposures were all on gain 0, offset 10, captured on my QHY163m using Sequence Generator Pro v3.
Lum: 75 x 300 secs
LRGB: 30 x 120 secs per filter
Again, I used Astro Pixel Processor to stack and calibrate the subs. I really love this program now I have got used to it. Its ability to remove light pollution gradients, in particular, is superb. I really must get around to completing a review and tutorial on how I use it.
The stacked and calibrated subs are then moved across into PixInsight for processing and combining. I wanted to try and bring out the dust lanes around the nebula, as well as keep the star and nebula colour vibrant without over-doing them. I think I have found a balance here – one I am happy with at this stage anyway. I started to use more complex methods of bringing out the dust using wavelets layers however I found I need more practice with these before I am competent in using them so I stuck to my usual masked stretches, a wide range of star, nebula and bright object masks, and then little adjustments until I reached the final image.
I am a lot happier now with my LRGB process, especially given the skies I have to deal with. The use of a CLS CCD filter in addition is, to my mind, a sensible step to take in order to block out unwanted light polluting light frequencies before they ever hit the sensor. Others disagree, but that’s half the fun of imaging.
Unless I have more clear nights very soon, it’ll be on to narrowband emission nebula until August when we get astro darkness returning in the UK and, with that, Andromeda!