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H-alpha cloud / structure near Omega Centauri - Does a photo of this exists?

ZWO ASI294MM H-alpha Globular Cluster
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Mauricio Christiano de Souza avatar
Mauricio Christiano de Souza avatar
I started a project on Omega Centauri last year and took some Ha frames just to see if there some faint signal in the background from whatever could be there using Nicolas' Rokinon 135mm f/2, ASI294MM and Antlia 3nm Ha filter. It turns out that looks like there is something there, but I have never seen it in any photos. Maybe someone captured it before?

Original Image:


Starless continuum subtracted and gradient corrected image:


Denoised crop (with dust spot):
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Alex Nicholas avatar
Alex Nicholas avatar
I have seen faint edges of it in widefield exposures of Omega Centauri before, but not where someone threw 30~50hrs at it to make it prominent. 

a worthy project if ever I saw one!
Daniele Borsari avatar
Daniele Borsari avatar
Interesting for sure and it indeed looks like it's real signal.

Can I ask you how you denoised that master? You took away all the noise, how do you do it?
Mauricio Christiano de Souza avatar
Mauricio Christiano de Souza avatar
Daniele Borsari:
Interesting for sure and it indeed looks like it's real signal.

Can I ask you how you denoised that master? You took away all the noise, how do you do it?

This is the raw continuum subtracted Ha:


First I used NXT for high frequency noise:


Then I used MMT for low frequency noise with a stretched and convoluted inverted mask:


Lastly I went for another go with NXT:


Beware that you will loose some details with this workflow. I did it this way because the signal is way too low and I don't think it is worth trying to preserve any details.
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