Orion Nebula - what colour?

[PorkyB]

My first deep space image was the Orion Nebula and like many people I keep coming back to it as it is so beautiful and has a real "wow factor".

The thing is, every image I take of it is a different colour.  Red, blue, purple, even a bit of green.  Why is this?

... and what colour should it be?

[ollypenrice]

The strongest emission signal is in the H alpha line so it has to have plenty of red. Green has to be a mistake! There are patches of reflection nebulosity which have to be blue.

A magenta-red would be where I'd put my money.*

Olly

*A good point from Narrowbandpaul on another thread. The H beta line, which traces much the same gasses and the Ha but less brightly, is blue. This would drag the hydrogen emission over into magenta, no?

[martin_h]

And yet when some people view it through a telescope they report a green tint?

[glappkaeft]

And yet when some people view it through a telescope they report a green tint?

That's because the color sensitivity of the human eye peaks sharply in the turquoise-green-yellow (http://en.wikipedia.org/wiki/File:Eyesensitivity.svg). 

[Stevie P]

Its colour should be how you want it and are satisfied with after processing, after all these images are for you to enjoy..

[PorkyB]

A magenta-red would be where I'd put my money.*

So maybe something like this , or maybe this .  This one looks a bit too red .

Its colour should be how you want it and are satisfied with after processing, after all these images are for you to enjoy..

You're right, of course.  We all do this for our own enjoyment.  I'd just be happier if I thought it was more technically correct.

[cantab]

I think that with most nebulae a "natural" appearance won't look as good, in large part because the Ha emission is so dim to our eyes.

The ones that always look a bit odd are "Hubble pallette" images, which map the Ha to green.

[ollypenrice]

A colour calibrated RGB has always given me something like the first image. Not that this really proves anything.

Oly

[lensman57]

My first deep space image was the Orion Nebula and like many people I keep coming back to it as it is so beautiful and has a real "wow factor".

The thing is, every image I take of it is a different colour.  Red, blue, purple, even a bit of green.  Why is this?

... and what colour should it be?

Hi,

This is the best that I have managed so far, it was taken back in early OCT using a cooled CCD. Hope that it helps.