PixInsight Forum (historical)

PixInsight => General => Off-topic => Topic started by: dhalliday on 2010 April 29 21:18:42

Title: Three channel NB imaging
Post by: dhalliday on 2010 April 29 21:18:42

I am trying out a set of NB filters,ie Ha,OIII and SII..on M97

So far I have just VERY faint stars with the SII filter.....
OIII and Ha look decent (15 minutes,f/9 binnned 2X2..)
SBIG ST2K..
In any event...how do I try to "bodge this data together"...?
Just call it RGB and assign colors...?
What about the lack of image in SII...??
Any comments or examples that others could show me..?

(Still have not figured out a HaRGB combo either....) >:D

Dave

Title: Re: Three channel NB imaging
Post by: Silvercup on 2010 April 30 06:31:28

Hi Dave:

First thing, you must decide the palette that you are going to use to combine images. You have several options but the most common are:

Hubble Palette: SII to red, H-Alpha to green , OIII to blue.
Palette CFHT (Canada France Hawaii Telescope): H-alpha to red, OIII to green , SII to blue.

You can assign H-alpha to red, SII to green and OIII to blue and you get a similar result to RGB.

If you have a lack of signal on some channels you can use a custom palette by mixing the channels.

See http://pixinsight.com/examples/deconvolution/Gemini-NGC5189/en.html (http://pixinsight.com/examples/deconvolution/Gemini-NGC5189/en.html)

Good luck. Silvercup.

Title: Re: Three channel NB imaging
Post by: dhalliday on 2010 April 30 18:32:36

Thanks...most helpful... 8)

I will post a result when the weather and moon cooperate..!

Dave

Title: Re: Three channel NB imaging
Post by: dhalliday on 2010 April 30 19:59:14

Meanwhile here is a "faked up" LRGB...using the Ha as R (and R as Lum)
http://www.flickr.com/photos/daveh56/4567193160/

 >:D

Title: Re: Three channel NB imaging
Post by: dhalliday on 2010 May 01 12:41:49

OK...that photo was so bad I deleted it...too much pain.. >:D

Here is an example by N Fleming about creating "synthetic" third channels,when one of the three is missing;
http://www.flemingastrophotography.com/ngc6888.html

And here is a BIT more Ha data...
http://www.flickr.com/photos/daveh56/4567463518/sizes/l/

Its the SII that is missing...(in M97..)

Dave
PS here is a crude HaRGB...
http://www.flickr.com/photos/daveh56/4569898064/sizes/l/