IKO - IC59 & IC63 Ghost of Cassiopeia Data - Winners!

[Grant]

We announced the winners live on 'StarGaZine' tonight and I am very pleased to post them here as well - many thanks for all your entries, I really hope the data gave you some enjoyment during lockdown, I certainly enjoyed seeing all the entries.

You can see all the entries here, the data is still available here if you want to have a play. The winners are:

Winner - Xiga

 

Runner Up: Skipper Billy

 

Runner Up: Spongey

Well done all! 🙂

 

 

 

[Spongey]

Congrats Ciarán for winning, well deserved if you ask me! 

Some great entries as usual. Looking forward to the next one already 

[AstroExploring]

Well done all! Some great images there 😃

[Skipper Billy]

Well done @Spongey and @Xiga  A worthy winning image Xiga. I would be very interested in how you tamed that screaming star - its something I always struggle with.

[Anonymous Astronomer]

Well done everyone!

[happy-kat]

It was a great challenge with the lively star, well done all.

[Xiga]

Thanks everyone for the kind words. I feel truly honoured! ☺️ I have to say, it came as a pleasant surprise when i found out last night. 

It's great seeing so many different takes on the same data. When i see what other people are able to do with their versions, it certainly gives me impetus to try out new things myself, so i find it a great motivation for trying to improve one's skills. 

My mount has been away for servicing for over 13 weeks now 🤨 so it's been nice to have some data to play with during that time, especially data as nice as this, so thanks again Grant for providing us with it. And a big thanks to FLO too! 😀

 

[Xiga]

On 28/02/2021 at 23:54, Skipper Billy said:

Well done @Spongey and @Xiga  A worthy winning image Xiga. I would be very interested in how you tamed that screaming star - its something I always struggle with.

Thanks David!

That star (Gamma Cas) was a real challenge wasn't it?! I'll try and show below how i went about adding in the 'lesser-stretched Ha stars' because this stage alone made a huge difference. From then on, it was just a case of making smaller adjustments. Unfortunately this will all be done in PS (i know you use P.I) but pretty much anything that can be done in one program can be done in another (once you work out how) so hopefully it will still be of some use to you. I'll try and keep the waffling to a minimum, so here goes:

1. Save 2 versions of the Ha stack using your favourite astro program. I use APP myself, so i do a DDP stretch and save it as a 16bit tiff. For the 2nd one, i save a linear unstretched version, also in 16bit tiff format. Obviously the stars are way too big in the stretched version, but we can still use it for all the nebulosity. Now bring the stretched version into PS and convert it to RGB (even though it's Mono) as this lets us view the pixel brightness in the usual 0-256 range. Now take a note of the Mean readout on the Histogram panel (for later). 

DDP: 

2. Now run Starnet++ on it, clean up any remaining star artefacts, and then Denoise it. These days, i'm liking Topaz Denoise Ai, but you can use whatever you fancy. 

Starless Denoised:

3. Now put the starless layer on top of the linear version in PS, and set the starless layer to Blend Mode Screen (note, normally i would put the stars on top in Screen mode, but i had to do it the other way around in this image due to Gamma Cas, which needed a mask). Also, when adding in stars to a starless image, don't be tempted to use 'Lighten' mode, it doesn't work very well on extended nebulae as you will usually end up with dark rings around a lot of stars (Lighten does work quite well on galaxy images though). Now select the linear layer, and start to manually stretch it, and stop when the stars are coming through at just the right size. I usually do about 4 stretches (i don't like the stars too small) and i like to use a mixture of both Arcsinh and regular stretches for this, as it keeps the cores down while still retaining their natural profile. Once done, now select the starless layer, and add a feathered layer mask to exclude Gamma Cas from the starless layer. Now Flatten (or do a Stamp Visible).

Lightly stretched stars: 

Gama Cas Mask 1: 

Results after Flattening: 

4. Now the stars should look good, but everything is obv way too bright, so we need to do a downwards Curve adjustment. For this, i place a point at the highest possible in Curves, which is at point 251, and then i use the downward arrow to lower it so that it gets close to the Mean level from the earlier DDP image. I usually stop on the high side, then place one further point mid-way and then lower that slowly until it's closer. This helps to preserve the very faintest of stars. We should now have an image that is very close to the DDP image from earlier, but with greatly reduced stars. 

Downward Curve: 

5. Even though Gamma Cas is already looking a lot better, it still needed more work. It was this part of the processing that i am struggling to remember exactly what i did, but i think i used an even lesser stretched version again, and blended that in. I have the mask that i used, you can see it below, but i think i also blurred the out halo a bit, and also used the shadows & highlights tool as well.

Gamma Cas Mask 2: 

7. Some minor star bloating tweaks to a couple of smaller stars, and that was the Luminosity layer done. After i merged it with the tonemapped colour layer, i then did a further bit of shadows & highlights to bring down the main nebulosity, but also on Gamma Cas again, to help tame it a bit more. 

Final Lum: 

Here's a screengrab of what the layers looked like in PS:

And finally, a gif showing the before (original DDP stretch) and after:

 

Sorry, ended up waffling on more than i intended to lol. I'm sure there are other/better ways to go about this, but this is how i do it at least 🤪 Hope others find it useful too, and if anyone has any ideas for improvements i'd love to hear them! 😀

Edited March 2, 2021 by Xiga

[Skipper Billy]

@Xiga Thank you so much for that detailed and easy to follow explanation. Very kind of you to share your method. Every day is a school day!!!!

Thanks again and congratulations on your win!

 

[PhotoGav]

@Xiga - that is a fantastic tutorial, some really great techniques in there, thank you for sharing. Great picture too, well worthy of the win! Congratulations!

Edited March 2, 2021 by PhotoGav