HA OIII Difference

[Ken82]

I've started to process some images i got on the California nebula last month and I'm amazed what appears to be a sheer lack of Oiii. I mean normally you can at least distinguish the nebula by looking at the formation of cloud and not the stars but on this particular nebula I fail to see much at all. 

Of course Hydrogen makes up most of the matter in the universe but it has surprised me more on this nebula than any other so far. 

Perhaps some more integration time would help (1.5hrs) ?? But actually im not convinced. 

Ken 

 

[Skipper Billy]

I share your pain - I am gathering the OIII on this target as we speak and its almost non-existent.

I am up to 7 hours now in 600 sec chunks and its still barely visible.

I will let you know if its worth pursuing when I stack the subs tomorrow.

PS - happy to share the stack if that helps you - my FOV is a bit tighter than yours.

 

[Adam J]

It's more normal to go ha and sii for this object for this reason. 

[Ibbo!]

IIRC the Jellyfish in Gemini is the same.

[ollypenrice]

4 hours ago, Ibbo! said:

IIRC the Jellyfish in Gemini is the same.

Not so sure. I found the OIII very interesting on the Jellyfish: it produces a distinctive outer shell rather like the outer shell of OIII around the Crescent. It was after seeing it in NB images that I decided to see what it would give to my HaLRGB image of the target.  It picks out the outer edges of the Jellyfish feature quite distinctly and, visually, helps lift it forward of the background nebula. It's rarely seen in broadband renditions but I think it was well worth the effort.

Olly

[Skipper Billy]

It is very faint - my stack of ~ 6 hours of Oiii data revealed a faint smudge when stretched !

Pixinsight managed to drag it out kicking and screaming eventually......

 

 

 

[Hallingskies]

18 minutes ago, Skipper Billy said:

It is very faint - my stack of ~ 6 hours of Oiii data revealed a faint smudge when stretched !

Pixinsight managed to drag it out kicking and screaming eventually....
 

That’s a superb effort.  I’ve never seen a hint of OIII on this from my Bortle 6 skies but you’ve shown me that it’s worth having a go at, maybe with faster optics.  I’ll have a try with the Samyang f2 lens I’m setting up....

[Ken82]

Nice effort David 👍 I’m going to have a try this evening once I put my son to bed. 

[Ken82]

First attempt Im disappointed but it does have some blue from the Oiii. Gradients from the full moon have killed me! 

I think firstly ill need to add some more data and secondly not a few degrees from the full moon! 

 

[Ken82]

So Ive tried my best to squeeze as much OIII out of the california as possible from 1.5hrs data. Quite disappointed but clearly Ill need to add much more data to the images next time round.

One thing I have learnt is that even using 3nm filters the full moon is still a royal pain! Lesson learnt,

It would be nice to also add some RGB stars so ill have a look through some old data and see what the final image looks like. 

Ken

[Ken82]

I've added just over 6hrs OIII now so that's it for me this year, onto other targets.

6hrs OIII, 2hrs HA, 2hrs SII

Ken

 

[ollypenrice]

I'd say that it was well worthwhile. Sometimes (indeed usually) a lot of effort produces a small benefit but that's why amateur images go on getting better and better.

Olly

[Knight of Clear Skies]

On 06/12/2020 at 14:10, Skipper Billy said:

It is very faint - my stack of ~ 6 hours of Oiii data revealed a faint smudge when stretched !

Looks like the visible OIII is centred on Xi Persei, which is the ionization source for the nebula. It's a runaway star lighting up part of a molecular cloud as it barrels past rather than a young star embedded in the nebula itself, which may account for the weak OIII signal.

I had a quick go at making an Ha/IR composite using some low-res data from the WISE observatory.