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Narrowband Veil Nebula


narrowbandpaul

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Hey

It just occurred to me that I never posted my finished image of the veil nebula surrounding 52 cygni. It was finished in early august. I am pretty sure its one hour per filter...

Sky90 at F4.5 SXV H9 with Astrodon 6nm Ha and S[iI] and 13nm O[iII], on an AP900GTO guided by FS78 and PHD guide.

Hope you enjoy.

I combine the images in the HST and CFHT pallete (Ha=red O[iII]=green S[iI]=blue)

HST first

8042_normal.jpeg

(click to enlarge)

Canada-France Hawaii Telescope second

8043_normal.jpeg

(click to enlarge)

and the Ha only version

8044_normal.jpeg

(click to enlarge)

Thanks for looking...

Some folk prefer the CFHT pallette for this object...what say you?

Best Wishes

Paul

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Hi Paul

Both are very nice and I don't think there is much to choose between them, just an observation, looking at the Ha shot there appears to be more detail than is coming out in the two colour shots, did you cut back on the Ha channel at all?

Best wishes

Gordon

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with the O[iII] and S[iI] being considerably weaker than the Ha, I couldnt push the RGB combined for max detail.

After aligning and combining the subs for each filter, I roughly equalize the histograms, so that their histograms look similar. Then I do a touch of sharpening and star size reduction. Then I can combine them into an RGB and adjust sliders until there is a contribution from each channel. Then I digitally develop the whole lot. Then levels and some curves. As i do the most severe stretching after colour combine, I am limited by the quality of O[iII] and S[iI] data.

I hope this makes sense.

Do you have any other suggestions...I cant push Ha too far or it will dominate the image.

I think I need better data for the oxygen and sulphur

Thanks for your comment, Gordon

Best Wishes

Paul

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After aligning and combining the subs for each filter, I roughly equalize the histograms, so that their histograms look similar.

Great images Paul.

Can you give me a quick explanation on how to do this please?

I am currently gathering my first set of OIII data to add to some Ha, and would be interested in how you do this.

Cheers :clouds2:

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well I go for the technique told to me by Richard Crisp. To ensure contribution from each emission line, the histograms have to have the same approximate shape. I do this using levels, and reducing the white point. Normally the O[iII] and S[iI] require more stretching, so more subs are usually required to get a good SNR.

For my bubble nebula image the oxygen and sulphur were so faint that I had to give them a small boost using levels and curves!

So just make the histograms the same shape using levels...if the Ha is still dominant then use curves to give the weak channels a boost. basically ensure that each emission line is evident in the final image.

Hope this helps

Paul

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