RCW32 (Gum15) HST Test Image

[PKay (Peter)]

I just wanted to see how much of each frequency was there.

23subs @ 5min each filter.

Standard HST palette (Si to Red, Ha to Green, O2 to Blue)

Ha is dominant, then Sii, and virtually no O2

Now I can only guess that spending more time on Sii is the way to go.

I read somewhere the ratio should be 6:1:3 (Sii Ha O2)

Any ideas?

Images attached show each channel (Ha, Sii, O2) and the SHO combination.

[Andy01 (Andy)]

Here is an interesting recent rendition for you to reference.


Some targets lacking in O3 respond well to an N2 filter. I tried that with this one.

Have fun!

[PKay (Peter)]

Hi Andy

Thanks for replying.

I did have a good look at John Ebersole's RCW32 image on astrobin and it led me to trying the HST palette on the 'Gumtree' (after M&T made me aware of the 'gumtree' in the first place).

Had a good look at your BBW56 image and it is very good.

Question: What is a N2 filter? I have no idea.

[Andy01 (Andy)]

Originally Posted by PKay

Hi Andy
Question: What is a N2 filter? I have no idea.

Ionized Nitrogen - the Nitrogen emission line is very close to Ha.
Ha is 656.2nm. N2 is 658.4nm - most Ha filters 5nm or more include the N2 signal, so only the narrowest (and most expensive) of Ha filters, 3nm allows one to seperate these two.

My BBW56 image was composed of Ha, N2 & S2, basically light that is red, redder and even redder still! So much careful thought & processing was required to create a tricolour NB image.

You can read more about N2 HERE

Cheers
Andy