old_eyes

Something special given how it was captured.

Another super image Olly. How many panels? Most planetarium software and star charts are not good on the LDN and LBN catalogues (unless you know of one 🙂). The bonus galaxies in these images are fun too.

I like that better.

Congratulations! That is a very nice California indeed. Good signal, plenty of fine structure and stars well controlled. The focus looks very slightly soft, but I don’t know if you were manually focusing or not. If it was manual my profound congratulations and envy. I could never get manual focus right. Personally, I wouldn’t worry too much about RGB stars. UK clear skies are hard to come by, and I would not waste imaging time. To be honest I wasn’t looking at the stars at all, just the lovely nebula.

I think that is a possible rather than a probable at the moment Gorann. It looks like there is something covering part of any bubble at the top left, but there is also a strong blue signal in a wavy line just above the Christmas Tree cluster that cuts across any bubble. It could be a very distorted part of a bubble, or a separate nebulosity cutting across, but it could also be that there are just a jumble of blue emissions scattered through the area. How you would definitively tell, I don't know. Maybe someone knows how you could work it out?

Indeed it does.

Very dramatic image Gorann. The red a bit too red for my personal taste, but lovely detail in the nebulosity. I am not sure about the large 'bubble'. There is quite a lot of general reflection nebulosity around there. I agree with @AdamJ - you need to separate it from the Ha emission and see what it looks like.

This part of the sky definitely having a moment. Lovely image, and a nice capture of what must be a very difficult target. I have RASA envy!

This is data on the Witch's Head nebula (NGC1909) combined from several runs on Pier 5 @Roboscopes in Spain (Tak Epsilon 180, ASI 2400MC Pro, Paramount MX unguided). A 2 panel mosaic in OSC, Processed in PixInsight. Rigel just out of shot providing a lot of flare, but you can see how it illuminates the nebula. You can also see several small galaxies. Thes made the processing a bit more difficult as they needed to be carefully masked before stretching the main nebula (or clumsily masked depending on how well you think it worked). Several of the galaxies are identified in this annotated version.

But what an image though. It keeps getting better and better!

Olly, See my comment on your thread. The balance of the the calibrated and stacked data seems to be different. In my data, the nebulosity at the bottom of the image has the exactly the same intensity as the weaker parts of the main hydrogen emission nebula. Different sensors and optics? Different integration times and hence signal to noise? Different sky conditions during capture? Who knows!

I have now done the best I can with the data I collected The raw data is definitely different. For example, if I extract the Lum from the original calibrated and stacked image, the intensity from the background nebulosity is exactly the same as the intensity in the weaker parts of the hydrogen emission from the main nebula. I have messed around with it various ways and I always end up with a weak emission area at the bottom of the main nebula triangle and lots of signal from the dust and gas at the bottom of the image. I wonder which stars are pumping the hydrogen emission of the main nebula and whether the gas an dust at the bottom of the image are part of the same structure, or separate and at different distances. Anyway it was fun to try and achieve a similar image, even if I failed in the end.

Data from Pier 5 @Roboscopes in Spain (Tak Epsilon 180, ASI 2400MC Pro, Paramount MX unguided). 30 x 240 sec subs. Processed in Pixinsight. Not as beautiful as Olly and Paul's version, But satisfying nevertheless. This is mine: And this is the vastly superior Kummer & Penrice version. )

Olly, I like the second version. The starfield feels much more real, and toning back the intensity of the nebulosity gives it a more ethereal look. I think you are absolutely right. Instead of searching for the perfect rendition, we should be happy to produce a range of images, each of which highlights different features of the target. Highlighting the structure of the nebulosity, the ropes, threads, folds and twists often means a less 'realistic' image, but the structure is real, and pulling it into the foreground illustrates what is really going on in these astonishing objects.

Lovely image Olly. Smooth and full of detail. It is massively rich starfield, and I can the see the difficult choices about how much to supress the stars and how much colour and flare to allow. I have a similar FOV from the Tak Epsilon 180 at Roboscopes that I am currently working on. You image tells me I probably need to hold the stars back more, and treat the nebula a bit more gently. As usual an inspiration. Thanks for sharing.

UPDATE. So none of the obvious things worked . Went through the drying and recharging the desiccant protocol, alternative power supply, new USB cable, and direct connection to a separate laptop bypassing the hub and my pier mounted computer. Atik could not think of anything else to try so off it goes to them for (hopefully) repair in Portugal. All I have to do now is navigate it through the customs system - the forms look horrendous and I could be liable for import duty both ways from what I can tell. Thank you Brexit!

Not yet. I do not compare with the true masters, but I am making progress and perhaps one day 🙂. Other images are scattered around this site. Both from Roboscopes and my home observatory. One day I will sort them out, but at the moment - too much data!

Oh - I forgot. There was a small amount of LocalHistogramEqualization added between 9 & 10 to improve the contrast of the wisps and threads in the nebula.

The data is good as I am using a remote observatory in the mountains of southern Spain (www.roboscopes.com) rather than my cloudy, murky backyard in North Wales. However, even here only about half the subs were usable due to high thin cloud (that plays merry hell with faint nebulae). All processing was done in Pixinsight. This is one-shot-colour so we are RGB all the way through. If I remember, the processing went something like this: Basic calibration and stacking using WBPP DynamicBackgroundExtraction to get rid of gradients BlurExterminator to control stars - I was using a 300sec exposure so stars got a bit big SpectrophotometricColorCalibration to adjust colour balance using a preview of part of the image I felt was genuine sky as the background reference Starnet2 to remove stars and create a star mask NoiseExterminator on the nebula image to reduce colour noise in the background. I am trialling NoiseExterminator at the moment. EZ-Denoise gives about the same result to my eyes, but NoiseExterminator is faster MaskedStretch to see what I am looking at for further stretches RangeSelection to create a mask that would protect the galaxies in the field. As the outer layers of the galaxies were the same brightness as parts of the nebula, I imported the range mask into a paint program, and painted out any nebula and the halo of the bright star 44-Serpens so I would only protect the galaxies. Then imported mask back into Pixinsight and applied to the nebula image. GeneralizedHyperbolicStretch to reach a final stretch I was happy with HistogramTransformation to get a black point I was happy with ArcsinhStretch on the star mask to stretch and boost colour PixelMath to combine the two images using the max(starless, star_mask) function to choose the brighter of the two pixels at each position. Seems complicated when I write it down, but it all flows quite naturally. The only place where I had to go back and redo a couple of times was 8 & 9. I spent a while figuring out how to do the stretch without blowing out the galaxies. Couple of false starts there.

My first process on 4 hours data on SH2-73 in Hercules on the border with Serpens. Pier 5 @Roboscopes in Spain (Tak Epsilon 180, ASI 2400MC Pro, Paramount MX unguided). I am happy to have pulled out this faint reflection nebula, but it was a bit of a struggle as there are a number of small galaxies in the field of view that tended to blow out or look very weird if not carefully masked during the stretch. Anyway - here we are. The bright star to the top right is 44 (pi) Serpens.

Thanks Olly I think I see a touch of the green you noted in my Rosette image. It always seems to turn up if I push to get the background nebulosity. In this case it was not too obtrusive, so I decided to leave it.

Captured on Pier 5 @Roboscopes in Spain (Tak Epsilon 180, ASI 2400MC Pro, Paramount MX unguided). OSC image - about 2 hours exposure per panel. Processed in Pixinsight. I came up with various versions, of which I liked this the best for the display of the background nebulosity.

OK. I extracted a green colour mask, applied it to the image, and nudged the green down in the unprotected area. If I pushed it too far, it went from brown to distinctly red, losing what I think is the essential nature of this part of the image. So this is a small shift. Better?

Olly, I did no NR until I had got a starless stretched image. Then I applied a mask to the whole of the nebula and used EZ-Denoise on the background. Boosted the stars a bit more than in the previous image and came up with this: I don't see a huge difference in detail in the nebula, but maybe you think this is a better balanced view? It certainly makes the brown dust bottom left a bit more interesting.

Olly, The dust is real I am sure. I can see it in the individual subs if they are stretched to buggery (technical term!). Whether the dust is that colour, and whether it has been overboosted by processing are completely separate questions! Processing sequence was: WBPP, DynamicBackgroundExtraction, BlurExterminator, SpectrophotometricColorCalibration, EZ Denoise, Starnet2 separation of stars and nebula. Followed by separate processing of nebula and stars. So a fairly gentle noise reduction after colour calibration and whilst the data was still linear. I generally get as much of the basics done as possible whilst the data is still linear. Feels more logical. I will re-process omitting NR and see if the brighter areas seem to have more detail. When you are happy with your process, please let me see it. It would serve as a good benchmark for me to compare with my own work. As you know, I am still in the foothills of processing mastery.