Narrowband - How do you know if the target is suitable?

[swag72]

How do you know whether your target is going to be good for narrowband imaging? Is there certain types of nebula that respond better to narrowband imaging? Are galaxies any good for narrowband?

There's loads of great NB images on the forum, but if you want to do something a little different, I'd rather not waste time if some things just don't benefit from it.

Would welcome your thoughts on this.

[steppenwolf]

Emission (rather than reflection) nebula respond well to Ha and OIII so pretty much any will respond well. The same applies to SII but to a lesser extent which is why you often see images posted up here that only have Ha and OIII content mapped as Ha (Red) OIII (Green) and OIII again (Blue).

Hydrogen beta (Hb) is also present in much smaller amounts in emission nebulae and can be used as a 'blue' channel.

Planetary Nebulae are particularly rich sources of OIII emissions.

[swag72]

Cheers Steve - Do galaxies benefit from any of this magic? Or are they just better as LRGB?

[riklaunim]

Cheers Steve - Do galaxies benefit from any of this magic? Or are they just better as LRGB?

Sometimes H-alpha can be done for galaxies that have some H-a emission (look at the red blobs in M33 images for example).

[Whippy]

Cheers Steve - Do galaxies benefit from any of this magic? Or are they just better as LRGB?

I did M51 with a Ha layer and it made a very noticeable difference. Basically, if a nebula is red, then it's an emission nebulae so it should respond well in Ha.

Tony..

[Martin-Devon]

Sara - I think your question is very relevant, it would indeed be nice if there was a list or spreadsheet for which targets make good versus poor narrowband targets. In particular at this time of year - does M42 respond well to narrowband filters or is it strictly an LRGB target?

[swag72]

Would be interested in an answer to this question as well Martin - I think that someone has done some narrowband M42 very recently, so I think that's it's definately doable.

[ollypenrice]

To ditto Steve, it's the emission nebulae and planetaries whch sing in NB. However, galaxies won't work in NB alone though their active regions will brighten distinclly when Ha is added to red. Likewise Ha added to red has a dramatic effect on emission nebulae in LRGB imaging. M42 is a funny one because the Ha does not trace the broadband red all that closely. One of my favourite M42 features, the little hook or finger poking out of a hole, tends to disappear in Ha.

I always use the pic below as the ultimate example of the benefits of an Ha addition to the red channel. On the left, without. On the right, with. I think the benefit is fairly obvious!!

Olly

[swag72]

Great example there Olly, thank you.

[MushroomBill]

Hi. I was made aware of a list on another forum - am I allowed to link to it here? (sorry newbie and all that)

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