Narrowband Imaging in heavy LP?

[Naemeth]

I don't have a CCD yet, but thought that, since you can do NB imaging in Moonlight, can you get good data from the middle of a city in NB - even one like London?

[davew]

It depends on your light pollution. If you have a broadband light source causing you problems then possibly not. The usual stuff we contend with, yes you can.

This idea that the moon has no effect on narrowband isn't correct. It has less effect but not non. I have all but given up OIII imaging in moonlight and I've got a 5nm filter. Ha can be reasonable if you take more subs and work on your curves. If there's light high cloud or a great deal of dampness in the air then even Ha can be a pain. At the very least you may need to avoid the area around the moon.

Dave.

[Naemeth]

It depends on your light pollution. If you have a broadband light source causing you problems then possibly not. The usual stuff we contend with, yes you can.

This idea that the moon has no effect on narrowband isn't correct. It has less effect but not non. I have all but given up OIII imaging in moonlight and I've got a 5nm filter. Ha can be reasonable if you take more subs and work on your curves. If there's light high cloud or a great deal of dampness in the air then even Ha can be a pain. At the very least you may need to avoid the area around the moon.

Dave.

The majority of the city glow is orange, not white, fortunately .

[davew]

The majority of the city glow is orange, not white, fortunately .

Sounds ok then. I would always advise you to just get out there and try it anyway.

Here's what I've found with OIII.... In a dark area, say Dalby forest, on a moonless night I get around around 1% or so sky background. In South Manchester with no moon around 3% plus. With moon up it climbs over 5%. What this means for me is that the signal I want is not much above the general background figure, if at all.

With Ha things are better all round. I can get a strong signal target to show but the thin stuff around it either disappears or is blocky and noisy if the moon is illuminating the gunge.

Dave.

[Jessun]

It is possible, but the result will always be worse than from a dark site. The problem is not that someone is shining a light at you, the problem is that light is reflected in polluted air, more LP can often mean worse visibility regardless of the orange hue - which in itself is no problem at all - even with a OSC.

It's worth doing though, and narrowband really opens up new targets for you. Despite lack of cripsness in my images I find it enjoyable to do.

Here are two recent examples what can be done from the very centre of the second (I believe) largest city in France with a flood lit fasade and moon light! Narrowband filters used on an Atik 460EX.

/Jesper

[ollypenrice]

Great results from Jesper there, and my stepson lives round the block. If Broadway is any brighter I'd be surprised!

Malcolm Parkes used to post Ha and other NB data from London. http://www.malcolmpark.com/portfolio/astro.php?pg=3

Olly

[Jessun]

Haha, I'll give you Broadway Olly! Pink and bold! I I know it will make you cringe, but it can serve as another LP 'demo'. (That is not to say that it is top notch, but it will show what can be done by a mono newbie - me)

/Jesper

[ollypenrice]

No cringes, though apologies for turning Malcolm Park into Malcolm Parkes.

Olly

[davew]

Very nice. Just to give it some balance, this is a sub of a fairly well know object taken in OIII with the moon up.

I should have carried on

Dave.