Quote:
Originally Posted by avandonk
Most extended objects look very similar in NII and HA. The NII seems to have better detail. The 'forbidden' N[II] transition needs stars high in UV to stimulate emission of N[II].
The Helix Nebula shows a great deal of difference.
I hope to get some HA tonight of SH308 to find out.
bert
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Thanks for that Bert. I'll have to get an N11 filter at some point.
I had a go at SH2-308 last night with the CDK and Trius at F4.5. I was only picking up about 1/10th of it at that image scale. Its a job for my refractors and the Proline I think! Its quite a large object. A shame as it was picking it up quite well. I may do one anyway at some point showing just part of the arc. Maybe that end part where it tapers in.
Greg.