Quote:
Originally Posted by Merlin66
Bert,
Very interesting....
I'm sure you could similiar results with other filter combinations which absorb at the emission wavelengths you want and give good transmission in the other regions.....??????
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It is a matter of matching the whole optical train and filters for meaningful subtraction.
It just cannot be done with filters that are not close optically to NB filters.
If this was possible it would have been done by now
Star intensities are thousands of times higher than very dim emission nebulae. That is why there are still quite bright remnants of some 'subtracted' stars. The spectral emission of stars are also very different that leads to these remnants.
Once the colour data is plugged into the holes or dimmer remnants of the 'subtracted' stars the result would be far better than dealing with colour haloes of stars of overstretched narrow band data due to a paucity of inherent faint nebular signal to noise. Very weak SII causes those purple haloes in Hubble Palettes.
Bert