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KevS

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29 minutes ago, DaveS said:

At the moment I'm wondering how much of that is genuine [NII] and how much is residual H-alpha that's creeping in through the overlap between the lines. Maybe a careful subtraction of one from the other might give me some idea.

That's what I was wondering.

Would it be easier to make a Ha NII NII image?  

The H O O versions of this clearly show that the Ha and OIII are indeed different. 

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This is the Broom I did two years ago in NHO

843994105_6hourDDP.thumb.jpg.bbc116e4802e9568de2d4b025d4fc7dd.jpg

As you can see there is some pure HII (The green filaments), but I'm struggling to find pure [NII]. I think there may be some red patches in the tendrils just above and to the right of the main Broom.

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Can't you tell from the raw [NII] subs how much signal there is?

I seem to recall that the Cygnus Loop doesn't have nitrogen in it.  It does have hydrogen, oxygen and sulphur.  Other DSOs seem to have very little sulphur but do have nitrogen.

Edited by Gina

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My main aim in image processing is to produce nice sharp, colourful pictures in false-colour.  Not only does false-colour give pretty looking images but also brings out more detail/features.  Guess this is why NASA use false-colour with their Hubble images.  This only applies to nebulae and suchlike, of course.  Though I like to add Ha to LRGB for galaxies.  But I expect you know all this 😄

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1 minute ago, Gina said:

I seem to recall that the Cygnus Loop doesn't have nitrogen in it.  It does have hydrogen, oxygen and sulphur.  Other DSOs seem to have very little sulphur but do have nitrogen.

OK, here's an HNN from the two year old data.

707137230_HNNDDP.thumb.jpg.fc4de24211ce6cf82deb23118fb49c17.jpg

Apologies for the rather rough edges, I just did an RGB synthesis and DDP. There's quite a lot of pure HII showing up as the red areas, as well as some areas suggestive of a lot of ]NII]

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I'm a bit confused.  I can't see any red, just shades of magenta and a little hint of green in the background.  Lots of detail though.

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Drat. Yes it looks magenta to mee too now. I suspect something wonky in the RGB settings, the magenta should be red as it's pure HII, any pure [NII] will be blue-green.

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I'm afraid I can't see any sign of cyan (blue-green) in that image.  The background hint of green is simply minus magenta.  HNN should show red and cyan colours.  Combining red and cyan gives magenta.  Sorry but I have to conclude that there is no nitrogen in that image.  The Ha is bleeding through the [NII] filter.

Edited by Gina

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OK, last one, I promise.

1284483239_HNNHistoonly.thumb.jpg.cc72562b1029bb5d1299d7a7657037de.jpg]

TBH I have to concede defeat, and my thinking that there might be significant [NII] was an illusion. Apologies.

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Gina, how are you finding the ZWO 8 place wheel with Astrodon filters? If I get one of these I can avoid having to swap my Sulphur and Nitrogen filters.

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Well, I'm sorry to have destroyed your thoughts about the gases in the Witch's Broom.  I never want to tell anyone they're wrong!

The ZWO EFW is fine - takes Astrodon filters with no problem - I'm using it now.  Has Astrodon 3nm and Baader LRGB filters installed.

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No problem Gina, will save me from pursuing blind alleys. I think I will order that ZWO wheel and swap cameras as well. Stellarium is giving me encouraging FoV results with the 130 f/7 and ASI1600.

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I can certainly recommend the ASI 1600 camera as well as the ZWO EFW 8 place wheel.

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Yes, I have an ASI1600 kicking around, currently it has a Leitz 180mm f/3.4 apo on it from when I was going to SGL2019. It'll also be a good match for the Leo Triplet when it comes around.

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Don't know when I shall be imaging again!  CO shows bits of green after 11pm tonight but I would have ti traverse the swamp to get to the observatory.  After that there is no clear night sky in the forecast for the next fortnight!  Oh well. not to worry - I have plenty of things I can design and build.  Like a dual imaging rig as well as projects already on the list.

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3 minutes ago, Gina said:

I would have to traverse the swamp to get to the observatory.

What happened to the path plan ? :grin:

CO says clear here early morning not sure it's worth waiting up for looking at last nights subs they haven't survived the moonlight very well despite the 3nm filter.

Dave

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The path plan died!  The gravel I have has turned into a solid heap needing a pickaxe or better to shift.  I'll re-examine the problem next year when the weather is better (I live in hope).

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22 hours ago, KevS said:

Good evening everyone, confession time. I would like to nominate myself for "dork of the week". This afternoon for a little entertainment I transferred the imaging kit to a widefield 72 mm apo, resplendent with the new prima luce labs dovetail and rings. Keyed up for widefield M81 job. For the last 3 hours I have been wrestling with guiding, checking for cable snags, checking clutches, lots of swearing (obviously under my breath). I have finally twigged that when the guide camera went on its new Altair guide scope earlier today I rotated it to alter the cable run. I have now calibrated PHD to the new guide scope orientation and everything is going swimmingly.:BangHead:.

On a happier note I have just found a bottle of Tobermory 20 year old malt in the back of one of the kitchen cabinets from a trip to Mull 3 years ago. 

Cheers

K

Confusion he say "Always calibrate PHD2, for a few minutes wait, you will not regret!"

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22 hours ago, KevS said:

Good evening everyone, confession time. I would like to nominate myself for "dork of the week". This afternoon for a little entertainment I transferred the imaging kit to a widefield 72 mm apo, resplendent with the new prima luce labs dovetail and rings. Keyed up for widefield M81 job. For the last 3 hours I have been wrestling with guiding, checking for cable snags, checking clutches, lots of swearing (obviously under my breath). I have finally twigged that when the guide camera went on its new Altair guide scope earlier today I rotated it to alter the cable run. I have now calibrated PHD to the new guide scope orientation and everything is going swimmingly.:BangHead:.

On a happier note I have just found a bottle of Tobermory 20 year old malt in the back of one of the kitchen cabinets from a trip to Mull 3 years ago. 

Cheers

K

Confusion he say "Always calibrate PHD2, for a few minutes wait, you will not regret!"

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2 hours ago, DaveS said:

OK, last one, I promise.

1284483239_HNNHistoonly.thumb.jpg.cc72562b1029bb5d1299d7a7657037de.jpg]

TBH I have to concede defeat, and my thinking that there might be significant [NII] was an illusion. Apologies.

I've just done a bit of Googling and there isn't a vast amount of info out there.  It seems that M27 may have strongly differentiated Ha and NII.

TBH,  I've recently gone to 3nm for Ha and OIII.  I've put off the SII because I don't think that I have ever seen anything that showed any pure SII signal.  It always looks like the Ha with a different stretch.  I'd love to find a third narrowband filter that contributed something unique, but I'm not sure that it exists.

 

Edited by don4l

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I fear you could be right but I reckon to have tri-colour DSO images, mostly using Ha, OIII and SII.  Also, I reckon to have found some NII in Orion but can't find the image ATM.  This shows a tri-colour image of the Eagle Nebula with Ha, OIII and SII.

129184842_Screenshotfrom2019-06-1812-20-27.png.5363102952eb304cb1b9ffa4f9312df4.png

EDIT :-  Found the Orion image.

On 22/09/2019 at 23:02, Gina said:

Orion 28mm lens HON palette.png

Edited by Gina
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I found this *very* early experiment with [NII] on M42

645625278_1HourNIIstack.thumb.png.34913a511e9b859607022839d007ed07.png

Not sure how pure it is. 1 hour in (I think) 4 min subs. Focus is iffy (Before i got a Bahtinov mask probably). I have loads of other early stuff, but haven't looked at M42 properly since, concentrating more on the Rosette. which I find more interesting.

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22 hours ago, KevS said:

Good evening everyone, confession time. I would like to nominate myself for "dork of the week". This afternoon for a little entertainment I transferred the imaging kit to a widefield 72 mm apo, resplendent with the new prima luce labs dovetail and rings. Keyed up for widefield M81 job. For the last 3 hours I have been wrestling with guiding, checking for cable snags, checking clutches, lots of swearing (obviously under my breath). I have finally twigged that when the guide camera went on its new Altair guide scope earlier today I rotated it to alter the cable run. I have now calibrated PHD to the new guide scope orientation and everything is going swimmingly.:BangHead:.

On a happier note I have just found a bottle of Tobermory 20 year old malt in the back of one of the kitchen cabinets from a trip to Mull 3 years ago. 

Cheers

K

Confusion he say "Always calibrate PHD2, for a few minutes wait, you will not regret!"

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Once we get a clear night without a full moon I may try some experiments.  I want to build a dual imaging rig anyway so I can have a 5nm Ha filter in one and a 3nm in the other and take images at the same time.  Then I can put the images into PixInsight, Star Align and then use PixelMath to subtract one image from the other.  (5nm - 3nm) The result should give NII.  To be sure I had Ha and NII I would take OIII as well and try to form a tri-colour image

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Referring to my image above of Barnard's Loop, Angelfish and the area around the Horse's Head, it seems to me there's a difference in hue across theses areas that might show the existence of NII from the image subtraction.  This image is made from Ha, NII and OIII mapped to RGB as I recall

Edited by Gina

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