Enhancing Luminance with Narrowband...

[manojkoushik]

Hello all, recently I captured some luminance data for the crescent nebula. In addition I also captured some Ha data to improve snr. But I am unsure how to combine them.

You can find the masters here: https://drive.google.com/drive/folders/0B6waQZAzxHToaHVOZHF3bjRrUUE?usp=sharing

I tried the new combination method as described here: https://pixinsight.com/tutorials/narrowband/

I generated the continuum map after aligning, cropping and linear fitting the two masters. Then I applied TGVD and generated the broadband image but it seems to lose a lot of information when doing this. Not sure what I am doing wrong.

The other approach I tried is to just add the two masters with varying weights for Ha but this seems less than ideal.

Any help in how to combine the two would be much appreciated.

thanks!
Manoj

[manojkoushik]

anybody?

[dzso.bacsi]

Hello Manoj,
Have you seen this tutorial? It might help.
http://www.lightvortexastronomy.com/tutorial-combining-lrgb-with-narrowband.html
Cheers

[manojkoushik]

This is exactly what I was looking for! thank you so much. Turned out great. Will post fully processed one soon.

[stevek]

Harry has done a great video tutorial on this as well at Harry's Astroshed.

I was likewise lost as to how this was done until I watched his video.  Excellent.

Also, enhancing luminance channel with Ha is not in fashion nowadays.  It is better to blend the red channel with the Ha.

[akulapanam]

The new combination method is missing some important steps that Vincent has never really filled the community in on.  A couple of us tried to fill in the gaps on Cloudynights but never got great results.  Maybe he teaches his details in his classes?  It would be nice to have a script.  His previous method is built into the NBRGBcombination script and you also have the undocumented HaRVB-AIP and SHO-AIP scripts as well.

I have always used PixelMath to integrate HA into LUM however Warren's Inside PixInsight book suggests that you use the image integration script to do this on a noise basis instead of a factor basis.  Juan also seems to suggest that here.  http://pixinsight.com/forum/index.php?topic=6042.15  Don't forget you also should blend some ha into blue as well as red.

Long answer is that there are many methods that can work and that it is a poorly documented/confusing area.