[Placidus (Mike and Trish)]

Originally Posted by Paul Haese

I really like the E version Mike. RGB stars and NB detail.

Originally Posted by marc4darkskies

Very interesting analysis M&T! A nice image too!

Thanks very much Paul and Marcus.

It will be interesting to see how it goes on other nebulas.

If there is no, or negligible, reflection nebulosity, the technique is easy. A great weakness of the technique is that if there is reflection nebulosity, like in this case, you have to use experience and judgement to find representative parts of the image that you guess are pure emission nebula. The maths will then tell you unequivocally (to an amazing number of decimal places) whether you are right or wrong. Even including one single patch of reflection nebulosity hugely changed the multiple regression goodness of fit, from say 99.99% to say 80%, so there is no doubt about it. (A bit like testing for a gas leak with a lighted match).

But automating it would require some slow process like a genetic algorithm, where you randomly select a bunch of say 20 patches of the image, call that set A, then another random set called B, etc, etc, etc, and you pit them against each other in a survival of the fittest, where () fitness is the multiple regression goodness of fit. You choose the best 5 contenders, get them to mix and match their patches, and try again. That would keep me off the streets.

Nah, doing it manually doesn't take so very long.