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ic63 Gamma-Cass Neb HST


ChrisLX200

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This one was hard work, I got to the stage where I was sick of looking at this data! I still don't like the colours much - kind of muddy - but the problem is that it's heavily dominated by the H-alpha channel which means Green. Mapping the Ha to Red doesn't really work either. The SII and (particularly) the OIII channels were very weak which meant a hard non-linear stretch, which in turn resulted in increased background noise. So this is it for now until I can figure out something better...

My usual kit: NP127is, Moravian G4-16000, 10-Micron GM2000HPS, Chroma 3nM filters. 14 x 1800s Ha, 8 x 1800s OIII and 8 x 1800s SII.

ic63%20LRVB%20small_zps05gfasam.jpg

ChrisH

 

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Hi Chris,

This is an interesting target, I don't think I have seen it before so had a quick google of it. There are lots of interesting structures, I think I might add it to my to-do list.

Do you plan on adding anymore data to this? I'd also be interested to see the individual channels for this target (if you don't mind) to see what data each of the filters picks up.

There is a technique you can use (if you have the software) that could be beneficial for weak OIII/SII signal called tone mapping. The 'but' is that it is quite time consuming, involves removing all the stars from the data, extreme stretching of the faint channels and adding the stars back again later in the process. might be worth having a read - https://astroanarchy.blogspot.com/2014/04/tone-mapping-v20-my-lecture-at-neaic.html

You could also maybe try some layered noise reduction, trying to keep the detail of the structure but reducing the noise of the surrounding area?

Thanks for sharing.

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2 hours ago, ChrisLX200 said:

This one was hard work, I got to the stage where I was sick of looking at this data! I still don't like the colours much - kind of muddy - but the problem is that it's heavily dominated by the H-alpha channel which means Green. Mapping the Ha to Red doesn't really work either. The SII and (particularly) the OIII channels were very weak which meant a hard non-linear stretch, which in turn resulted in increased background noise. So this is it for now until I can figure out something better...

Hi Chris

You are spot on regarding the signal in SII and OIII.  I found that I had to collect RGB data as well.  As far as processing all this I blended the Ha with red (for the red channel) and OIII with blue (blue channel) then used the stretched/processed Ha data as the luminance layer.  This worked quite well - it is a tough target but keep at it - I can see you have good Ha data in there.

 

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3 hours ago, Robp said:

Hi Chris,

This is an interesting target, I don't think I have seen it before so had a quick google of it. There are lots of interesting structures, I think I might add it to my to-do list.

Do you plan on adding anymore data to this? I'd also be interested to see the individual channels for this target (if you don't mind) to see what data each of the filters picks up.

There is a technique you can use (if you have the software) that could be beneficial for weak OIII/SII signal called tone mapping. The 'but' is that it is quite time consuming, involves removing all the stars from the data, extreme stretching of the faint channels and adding the stars back again later in the process. might be worth having a read - https://astroanarchy.blogspot.com/2014/04/tone-mapping-v20-my-lecture-at-neaic.html

You could also maybe try some layered noise reduction, trying to keep the detail of the structure but reducing the noise of the surrounding area?

Thanks for sharing.

Thanks for commenting Rob :)  I'll be adding no more data this season, it's a bit like flogging a dead horse! The channels are in the image below (Ha, Sii and OIII) - already non-linear stretched.

ic63%20stacks_zpsfgzwaese.jpg

All the detail is in the Ha channel (no unique structure in the other two) which made it safe to use the Ha as a luminance, that reduced the noise considerably but I have left some noise there in exhange for retaining more detail.

ChrisH

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2 hours ago, orion58 said:

Hi Chris

You are spot on regarding the signal in SII and OIII.  I found that I had to collect RGB data as well.  As far as processing all this I blended the Ha with red (for the red channel) and OIII with blue (blue channel) then used the stretched/processed Ha data as the luminance layer.  This worked quite well - it is a tough target but keep at it - I can see you have good Ha data in there.

 

Yes maybe you're right - RGB would add something useful to this. It would have to be a very good [dark] night though - no Moon around to spoil things! Thanks for commenting :)

ChrisH

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I apprecaite the hard work here Chris and understand that more work may well be need to tame the background.  I do like the way the 'Breaking Wave' appears to be about to engulf Gamm Cass and is illuminated and glowing on this facing 'wave' of nebula - quite beautiful.

Barry

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Chris--wonderful FOV.  I note that you captured almost twice as much Ha as the others.  I wonder if switching tah around might not help lift the OIII and SII a bit--also, maybe binning the OIII and SII might provide more signal.  Just thinking.

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3 hours ago, Rodd said:

Chris--wonderful FOV.  I note that you captured almost twice as much Ha as the others.  I wonder if switching tah around might not help lift the OIII and SII a bit--also, maybe binning the OIII and SII might provide more signal.  Just thinking.

Yes you're right Rodd, it is a bit short on both SII and OIII - the OIII particularly is just so painfully weak it's barely worth the time spent capturing it (from my skies at least!). I had to stretch so hard I think noise would be an inevitable consequence no matter how much data I collect. I think I'll try an RGB combination if I can get a clear night with no moon..

Thanks, ChrisH

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Thanks for posting those channels Chris, wow the OIII is faint!

I've looked at an RGB image of the same target and I don't think there is much more OIII to capture, its just getting dwarfed by the HA.

Good luck in adding the RGB, it will be interesting to see how it turns out.

 

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I know exactly where youre coming from when you say youre sick of looking at something! But for a hard, hard target youve done alright. Perhaps you can put the data in the locker for next year and double/treble up on it? It should help with the noise.

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I think it's a lovely image. No question.

Tom and I went for an HaLRGB approach but did give O111 a pop. It wasn't very appetizing so we dropped the idea, given the prodigious amount of time needed to find the lower part of the wave anyway. I think this excellent target will continue to attract new approaches and still has some way to go before a definitive version appears.

Olly

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