Helix Nebula HOOS Work in Progress

[SB]

Hi Everyone,
This is work in progress for this target - comments welcome as to next steps.


HOOS colour palate. I used the SII to provide the yellow component of the image.

Ha 208 x 300 Seconds
OIII 100 X 300
SII 100 X 300

Quattro 800 ASI183MM

Many thanks

Chris

[Nikolas]

Huge amount of detail in this and it will be an astounding project when done, My own personal preference and this is just my own, maybe tone down the saturation a touch?

[Peter Ward]

As far as i know the Helix has no meaningful SII emissions, hence I'l spend that time capturing RGB stars....but hey...happy to be corrected if there really is something there.

The colour is, well, colourful, but 70's pop art is not exactly accurate.

The helix is primarily red with a teal/cyan core. Better to respect the light?

The depth however is uber impressive. Nice one :thumbsup:

[SB]

Hi Peter ,
Thanks for your helpful comments which I take onboard. I have attached my SII stack for the Helix, so there does appear to be reasonable amounts of SII. Do you have suggestion as to what colour to assign for this wavelength?

Many thanks

Chris

[Peter Ward]

What's the bandpass of your SII filter? I went 10 hours with a 7nm filter and
only got noise.

The SII data you have captured simply might be leakage from
a broader pass filter. :question:

[g__day]

I agree - the word astounding certainly does leap to mind!

[keller60]

Interesting point, all filters pass through off-band light flux.

Chris, your SII data seems to mimic the Ha emissions, which I'm guessing would look like a flood light with the same exposure time.

Assuming the SII signal is not "leakage" and is there, then the relative brightness to the Ha data would be vastly different hence, the combined colour should not depart much from Ha red.

Just my 2 cents worth.

[Peter Ward]

Did a little digging...


According to professional images, the SII signal (which I failed to detect in my feeble attempt) is there.

You have done very well to get any signal....Kudos to you Chris :thumbsup:

But the signal is *extremely* weak compared to the Ha and OIII. Hence as Bill suggested, it should not contribute much to a NB rendition.

But, sure, while you can alter the relative intensities....the question then becomes: what are you showing by doing so?

If doing so reveals a structure at a particular location, then great.

If it makes something that normally looks red, but you can make it look orange.....the, meh....maybe not :question:

[SB]

Hi Bill and Peter
Thanks for your interesting post. I’m using a 3.5nm Antlia filter. On other targets I get good differential between Ha and SII so I was confident that I was getting SII signal. Point taken about colour. Would you normally suggest HOO on this target?

Thanks
Chris

[Peter Ward]

The Antlia 3.5nm clearly works very well. (no so much my earlier 7nm Baader effort)

HOO? ... nup.

I'd go uber-deep with Ha, OIII and add RGB or even LRGB to make the stars look pretty, but that's just me.

But you don't need my bias.

What ever "floats 'yer boat" works too. :)

[SB]

Hi Peter
This raises a good discussion about why in particular the Helix should have natural colours when most other non-broadband objects use SHO, HOS and other colour palates - essentially painting nebulosity with false colour.

Chris.

[Peter Ward]

Faint levels of SII aside, the Helix outer structures are dominated by Ha and the inner by OIII.
Those two regions are spatially well separated and the emissions sit nicely within the visible spectrum (i.e red and blue/green).

So you can enhance, rather than alter, a RGB or LRGB image with that data
to better show the red and blue/green structures.
One of the best examples of this approach is here (https://chart32.de/images/phocagallery/galleries/planetary-nebulae/ngc7293_lrgbhao3_80.jpg)

I'm very much a fan of image enhancement, rather than a "paint by numbers" approach.

But as I said, if you want to re-map the colours of nature there are no laws against it.