More Jellyfish!

As per my last post the Jellyfish I think required more than the 9h data I’d collected so far. The opportunity arose last night to grab several hours, the weather forecast in my area showed clouds rolling in during the early hours so I set up an Advanced Sequence in N.I.N.A. on this one target until Nautical Dawn (or Horizon limit) with the intention of keeping an eye on the sky as we got towards 11pm. At 11 it was definitely starting to haze over with some high clouds. Up until that point the seeing had been pretty good and a late Moonrise meant I think I’d got some good images (FWHM figures were around 2.75 – really good for my setup). I decided to stop the session and move to grab some darks, before bringing in for the night.

At the end of the darks cloud was definitely thickening, so good decision. I’d already decided that when I was adding data I was going t start getting more selective in the subs quality, so I saw no point in pushing on trying to grab a few through the high haziness.

Darks collected, rig indoors. Flats the following morning. My usual setup including the l-enhance filter running at ISO800.

Here are the nights totals:-

1. 95 3m Subs at ISO800

2. 15 3m Darks

3. 30 1s Flats (iPad and White T-Shirt method)

Adding to the previous 2 nights session brought my total up to XX of integration. Before stacking I was more ruthless with the lights (as I mentioned more emphasis on quality than just quantity). Using DSS I registered all the frames in 3 groups and taking each group on its own merits:-

1. I removed subs that were much lower score than the max in that group. If the scores were fairly consistent then I would not have done this but I did remove several frames where they where <25% of the maximum.

2. I removed subs where the # stars detected where <25% of the best in that group.

3. I was then going to move on to FWHM figures but actually after testing the subs in each group to the first two criteria there were non that I felt needed to be removed.

12h 19m of Integration total.

Result

Following my normal simple workflow in Photoshop (Convert to 16 bit, Levels, Curves, selective colour boost). A good degree of cropping had to be done as the 3 nights did not exactly overlap, in fact a little learning opportunity here, it pays to match the rotation not just the centre of the image as over 3 nights spanning around 1 month the rotation of the image meant I got more stacking artefacts than I think I would have if I had orientated the same each night.

Jellyfish after 3 nights

Not sure if the 3 nights show in the image quality as much as the benefit of having more options for stretching and manipulation of the final without it looking too stretched and false.