A bit of a mouthful, as a shorter name lets call it the green comet, the green comes from the carbon based chemicals in the head (diatomic Carbon). At you may had read elsewhere this is a Long Period comet, meaning we definitely won't be around if it does another visit, 50,000 years is mentioned but this is not certain!
I had a couple of session imaging this, one about 2 weeks ago where I was shooting quite low to the horizon and I wasn't at all happy with the result. This second attempt I actually did not hold out much hope for, there was a 70% Moon and it was very windy (gusting 40 mph). It may be that I have a fairly lightweight setup on the HEQ5 Pro mount and the fact that I was in a fairly sheltered spot but actually the images came out 'ok'. As you will see the tails of the comet could be more distinct and the Moon definitely did not help with that aspect.
I imaged for about 2 hours using my usual camera set up and the UV/IR Cut filter, each image taken for 60 seconds. This imaging session happened on the 31st January 2023 where the comet was only a day or two away from its closest approach to Earth. I guided on the background stars during the imaging, rather than guiding on the comet and followed the tutorial on Comet Processing in Siril, which is very good by the way. The Registered star images were Histogram stretched which was applied to the Sequence of around 60 images. This was then outputs as the following MP4 file to produce a couple of seconds of the comet moving - this is actually showing movement of the comet over a period of about 1 hour.
In terms of a still stacked image I ran two registration processes, one on the stars and one on the comet in Siril, stacking them both as per the aforementioned tutorial. Initial Histogram stretch of the Stacked Stars and the Stack Comet images was performed. The same histogram stretch was applied to both images by adding the two images to a single sequence then using the Histogram Stretch's 'Apply to Sequence' feature.
The two images (Comet and Stars) were then converted to 16bit Tiff then loaded both into Photoshop. The two images were processed separately.
Stars image was mostly to bring up the vibrance and saturation of the stars, the intention was that the resulting image was quite colourful to complement what I was expecting to be quite a green comet.
The Comet image was processed to bring out more of the detail of the trails while at the same time keeping the noise under control, Texture, Clarity and Noise Reduction in Camera Raw proved to be my friend.
The two images were then combined using a Screen Layer.
As hopefully you can see there is a definite green tinge to the coma, you should also be able to make out the Ion tail coming down at the 8 O'clock position. The main tail is very faint in this image but is coming down at the 4 O'clock.
This is one of the those left field projects, not something you get to do very often, so there are some definite lessons learned:-
Moonless night would definitely be an advantage, it could be I need to be more careful with the post processing in order to get the elongated gaseous tail, which is definitely very faint here.
Be careful with the framing, perhaps watching a few images without tracking to determine the position, this would definitely make the video easier to work with as you could keep it in frame longer. In this particular example it would have been better to start off the imaging towards the right hand edge of the frame rather than the centre.
An interesting project. Less Moon and more careful framing next time... 50,000 years maybe!
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