Adding Ha data to OSC data.

[Topographic]

Hi

I have data on M81 from last night and tonight I am going to use an Ha filter with my ZWO ASI183MC Pro. Do I load both using the Compose module, if so how?

Or combine two developed images.


Thanks

[admin]

Hi,

Much depends on what your goals are and the characteristics (e.g. exposure times) of the datasets.
You can add Ha as color, luminance, both. Do you want to retain visual-spectrum colors? etc.

(see also here https://forum.startools.org/viewtopic.p ... 573&p=6731)

Any further information would be really appreciated!

[Topographic]

Hi,

Much depends on what your goals are and the characteristics (e.g. exposure times) of the datasets.
You can add Ha as color, luminance, both. Do you want to retain visual-spectrum colors? etc.

(see also here https://forum.startools.org/viewtopic.p ... 573&p=6731)

Any further information would be really appreciated!

I have 55 x 4 minute subs taken with my SW 72ed, ASI183MC Pro, with Astronomik L2 ir/uv filter. (calibration frames done) Image attached.
I want to add Ha (Baader 7nm filter) to the existing image, keeping the colour. I am assuming I may need more or longer subs for Ha (Bortle 3)

I am happy to use the existing image or redo, being in 'lockdown' here in SW France leaves me with lots of time.

thanks

David

[admin]

Thank you.
Given you object is a galaxy (which is usually poor in Ha detail) and not a nebula (which is usually rich in Ha detail), you will want to add the Ha to your red channel to make the HII areas in the spiral arms stand out.

There are a couple of ways of doing that.

The most flexible, fool-proof way is to create a new red channel (for the purpose of coloring only, but not luminance!). You can use the Compose module to extract the red channel from your full-color datasets. Just load your color stack into the red channel only and it will extract just the red channel and create a "black and white" dataset out of just that channel (if Channel Interpolation is On). You can then save that dataset and extract the next one.

Once you got these two mono datasets (one with red channel, one with Ha), you can use the Layer module to create a blend, or you can use the Compose module (set Luminance, Color to L + Synthetic L, Mono) to create a blend (also in mono). Then save this blend. This will be your new red color channel.

Now use the Compose module again, set Luminance, Color to L, RGB, and load your full-color dataset as Luminance, Green and Blue, while loading your newly created red channel as Red.

You should now be ready to process the luminance of your full color stack as normal, while the Color module will bring in coloring that consists of R+Ha, G and B.

The other way is to process you color stack as normal and save it away.
Then to process your Ha stack as normal and overlay the two processed stacks in the Layer module using, for example, a Lighten blend mode.

[jimmy101]

If it helps I have found that you don't need much blending to get that Ha pop in the red channel, maybe only 25%.

[Topographic]

Thank you.
Given you object is a galaxy (which is usually poor in Ha detail) and not a nebula (which is usually rich in Ha detail), you will want to add the Ha to your red channel to make the HII areas in the spiral arms stand out.

There are a couple of ways of doing that.

The most flexible, fool-proof way is to create a new red channel (for the purpose of coloring only, but not luminance!). You can use the Compose module to extract the red channel from your full-color datasets. Just load your color stack into the red channel only and it will extract just the red channel and create a "black and white" dataset out of just that channel (if Channel Interpolation is On). You can then save that dataset and extract the next one.

Once you got these two mono datasets (one with red channel, one with Ha), you can use the Layer module to create a blend, or you can use the Compose module (set Luminance, Color to L + Synthetic L, Mono) to create a blend (also in mono). Then save this blend. This will be your new red color channel.

Now use the Compose module again, set Luminance, Color to L, RGB, and load your full-color dataset as Luminance, Green and Blue, while loading your newly created red channel as Red.

You should now be ready to process the luminance of your full color stack as normal, while the Color module will bring in coloring that consists of R+Ha, G and B.

The other way is to process you color stack as normal and save it away.
Then to process your Ha stack as normal and overlay the two processed stacks in the Layer module using, for example, a Lighten blend mode.

Hi

I think I get it, when I have the data (next couple of days looking OK) I will try both approaches.

Thanks

David

[Topographic]

If it helps I have found that you don't need much blending to get that Ha pop in the red channel, maybe only 25%.

Do you think I need longer subs?