There are several ways to do continuum subtraction in Pixinsight. But which one best suits the M8?
Continuum subtraction in nebulas
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I'm not sure about these several ways, but I have my own method. I perform SPFC using NB method and Ha wavelength/bandwidth for grey channel. I do this for both red and Ha channel. When I have scaling factors I just scale Ha channel to match red channel flux (in Ha wavelengths). Then I just subtract red channel from Ha channel. This could be the most accurate way to do continuun subtraction and you get right factors from Gaia database.
I use @Charles Hagen's photometric continuum subtraction script, and add the narrowband back with the pixelmath he outlines here.
Sean Makin:
I use @Charles Hagen's photometric continuum subtraction script, and add the narrowband back with the pixelmath he outlines here.
Tommi Liinalampi:
I'm not sure about these several ways, but I have my own method. I perform SPFC using NB method and Ha wavelength/bandwidth for grey channel. I do this for both red and Ha channel. When I have scaling factors I just scale Ha channel to match red channel flux (in Ha wavelengths). Then I just subtract red channel from Ha channel. This could be the most accurate way to do continuun subtraction and you get right factors from Gaia database.
I've used this script before; it worked on some nebulae, but it wasn't satisfactory for M8. The method mentioned in Tommi's comment seems interesting. I'll give it a try. I don't know if you're feeling the same way, but it seems that the more data there is, the more difficult it is for the subtraction to be efficient.
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