Oh, and one more thing regarding N1808:
The well-behaved radial dust "spokes" coming from the central starburst region are very rare (or absent) in the other members of the population of bright galaxies.
I have searched tens of thousands of galaxy images for this sort of feature...... and it is either very rare, or absent.
I believe (from memory) that Dr William Keel (an expert in active galactic nuclei) did a similar search for low entropy radial features in the central parts of galaxies, and that he came to the same conclusion.
cheers,
Robert
P.S. the central starbust region in galaxies usually has high extinction in front of it, but this is emphatically not the case in this galaxy.
"Just for fun and profit", I attach here - for comparison purposes - the Far Ultraviolet + Near Ultraviolet image of NGC 1808, taken with the GALEX satellite.
FUV is displayed as blue and NUV is displayed as yellow.
In general, FUV is an excellent tracer of the distribution of massive hot OB stars ( and thus, it is a tracer of current star formation), but with the qualification that FUV light is highly subject to severe extinction from dust within a galaxy.
