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Narrowband

cfinn

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Everything posted by cfinn

  1. Very nice! I had another go using just a bottom right crop and colour calibrating the starless image with just that portion of the nebula. I get a different result, quite similar to yours, which demonstrates that this will be sensitive to the choice of reference point for the white balance. It's a stronger purple in my original image above since I used the entire heart nebula as the reference point, which exaggerates the fact that OIII is so strong in the fish head compared to everywhere else and there is just a trace of SII which leads to the purple colour. As can be seen from the chromaticity diagram below, only a trace of red is needed to generate something verging on purple.
  2. Yes, you’re right, some SII is needed in there as well to make the purple colour, otherwise it would just come through as blue. I did nothing to my image to make that happen, just the colour calibration using the entire nebula as a white reference. I’ll need to have another look at the SII and OIII masters now to check!
  3. I also like your image by the way. It looks great!
  4. The purples are real and represent where there is an over-abundance of OIII emission. I have the same as you in exactly the same place bottom right in the fish head nebula. If you’ve done the same as me using ColourCalibration in PixInsight and using the whole nebula as a white balance, this will be a natural consequence of that. These colours are nice as they are both visually appealing AND they tell you something interesting about the physics and the composition of the gases we are looking at.
  5. Indeed! Here’s mine that I posted a few weeks back as well, which shows it can be done with a refractor and a reasonable integration time with some careful processing. No RASA required! Though I’m sure it helps…
  6. Thanks Olly. What is interesting is that the colours came out that way straight out of PixInsight SPCC, so there was gratifyingly little effort required to get there. Just a colour preserving stretch and a gentle colour saturation enhancement!
  7. IC 410, colloquially known as the Tadpole Nebula, in reference to the two clumps of gas and dust near the centre of this region with little tails resembling tadpoles swimming through the water. This is another target that is so often captured in narrowband, so I wanted to do something different and bring out more faithful hues. The presence of OIII and SII emission is abundant here, which combines with the Hydrogen emission to create a beautiful palette of reds, pinks and purples. Several small reflection nebulae and some dusty regions are also present in this field. Acquisition details can be found on Astrobin.
  8. Second clear night in a row after a month of incessant cloud and rain! Monitoring my rig from inside in the warm while it snaps away with a Wyze cam 🙂
  9. Thank you for providing this wonderful data! As part of my workflow I used the very latest version of BlurXterminator with AI4, which does an absolutely unbelievable job of cleaning up the corner stars. Completely processed in PixInsight. Steps were as follows, following a few iterative attempts backwards and forwards: ChannelCombination - straight SHO palette, 1:1:1 ratio across the three channels. BlurXterminator with sharpen stars at a setting of 0.5 (reduce FWHM by 50%) and sharpen non-stellar at a setting of 0.9. ColorCalibration with a starless copy of the entire image (made using StarXterminator) as a white reference and a small dark area bottom left as a background reference. BackgroundNeutralization using the same background reference as above. Initial stretch using HistogramTransformation with settings transferred from the default ScreenTransferFunction. Stars are removed (unscreened) at this point with StarXterminator. Invert the star image, apply SCNR with default settings and invert back to remove the magenta halos. These stars are kept for screening back later and the following steps are applied to the starless image. Create a binary mask using the GAME script to exclude the Crescent Nebula and apply to the image. It's already very bright at this point and this avoids saturating it in the next step. A series of small stretches to the brighter parts of the image using GenaralisedHyperbolicStretch and carefully selected symmetry points to create a smoothly downward sloping histogram in log space. This creates smoother transitions in brightnesses across the mid-tones. Remove the mask applied in step 8. A final stretch with GenaralisedHyperbolicStretch to brighten fainter nebulosity and bring it to the fore. Re-apply the mask from step 8 for the next two steps to protect fine detail in the Crescent. An application of HDRMultiscaleTransform with 8 layers and a lightness mask to recover lost contrast and detail in the brighter nebulosity (particularly the top left). MultiScaleLinearTransform to slightly enhance details at various scales of interest with greater contrast. Remove the mask from step 8 again. Screen the stars from step 7 back onto the image. GeneralisedHyperbolicStretch in saturation mode using a mid-tones transfer function and a symmetry point slightly to the right. This boosts saturation in the nebulosity but not the background / faintest nebulosity. Finally, NoiseXterminator with a de-noise setting of 0.7 to remove noise mostly introduced from processing steps, as the data was mostly noise free to begin with! Hope you enjoy it. I find the range of colours and structures across the image completely mesmerising! The massive integration time really shows here. Charles
  10. This is great! Nice that you have a wider field than me to capture more of the dust. Having a RASA must really help with pulling it out too. I only captured a small portion of DG6, so it's really interesting to see it in its entirety here. Like you, I had to stretch the data much more than I would like to get the dust to have a strong enough presence in the image. This really blows out the nebula, so I also had employ HDRMT, but I think it is an extremely powerful and elegant technique that becomes mandatory for this kind of presentation. CS Charles
  11. I think this is fantastic. The detail in the dust lanes is just lovely. Well worth continuing. For me, the star halos are a little too prominent, but that is purely a matter of personal taste. On the other hand, it does give them a nice luminous quality. Did you use BlurXtermintor and adjust the star halos setting, or something else? Charles
  12. No no, it's all good! The critique is very welcome 🙂
  13. Here we are @Magnum. I adjusted the black point just a small amount to darken the background further but keeping it just below the point where it starts black clipping. I think it is a good improvement. Thank you for the suggestion!
  14. Best of luck! Let me know how it goes. I could begin to see the dust after only 1 hour of luminance, but it took quite a lot more to bring it out fully and it could easily do with 2 or 3 times more integration time. I had to use a lot more noise reduction than I would ideally like and I suspect there’s more detail that could be teased out with some extra time investment. It’s always a question of how much you are willing to invest in just one target and three nights is usually my max.
  15. Thank you for the feedback! Black point adjustment is always a subjective thing I struggle with and I think I agree in this case I could darken the background a little more.
  16. The Pacman Nebula in HaLRGB. I decided to go as deep as I could afford to with the limited moonless clear sky time in Luminance to really bring out the dust. I've not seen many examples that really showcase this as the Pacman is so often captured in SHO. It took a few processing attempts to get to the result I wanted, and I learned a lot of new techniques in PixInsight along the way. I think I am finally happy with the result. Full acquisition details and a description of my processing choices can be found on Astrobin. CS
  17. Many congratulations! I am on the list and would be interested to hear how much you end up paying with the current exchange rate and import duty. I would love to have my name drawn, but at the same time I dread the thought, as I won‘t be able to say no and it will cost me an arm and a leg!!
  18. I think this new offering from JTW looks fantastic. Friction drive with high resolution encoders as standard and a 35kg payload at £6k probably (when you include VAT and shipping). Expensive, certainly, but when you consider it’s basically a competitor to the 10 Micron GM1000 (priced > £10k) with 10kg more payload and a friction drive rather than worm gear, it looks like a bargain. Very positive reports on the Trident from what I can see so far as well, so bodes well for this one.
  19. Interesting. From the specs and the description, maybe a response to this. EDIT: I see the OP has already made this link - I missed it on first reading!
  20. Many thanks! @ollypenrice I personally think it looks better in RGB, with all the dust and reflection nebulosity close by. The plan was to combine the Ha data with R and L in an HaLRGB composite. Alas, clear moonless nights can be a rarity, so narrowband it was, but I still may get to it.
  21. This was a slog. The Cave Nebula is a surprisingly faint target and I acquired the OIII data under particularly unfavourable conditions, with a nearly full moon and passing high cloud. Nevertheless, I was able to make the 30 hours worth of data I acquired work hard in processing and am really quite satisfied with the result. I would like to get some RGB data next time I get a clear moonless night or two to make a natural colour equivalent. Full capture details can be found on Astrobin. Enjoy! CS Charles
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