My Imaging with Narrowband Filters
Given my ever-worse light pollution, currently at Bortle 8, it has become increasingly difficult for me to image the deepsky without some sort of LP or NB filter. Here I did a very long experiment in HOO with my L-eXtreme NB filter (25 hrs) and my L-eNhance NB filter (30 hrs). The L-eXtreme had a darker background and better HII regions, while the L-eNhance did better on the rest of the galaxy, including the fainter tidal tails. For the L-eNhance data I avoided the worst of the smoky nights, but even most "clear" nights generally had at least some level of smoke in the air, increasing background and reducing transparency. I hope this is not the new normal.

For this image, processing was done in Startools. In Photoshop I processed  the stars separately, so then I could use the APF-R multi-scale unsharp masking (as used by NASA imaging) to deblur the image. I applied final noise reduction (NoiseXterminater), color and levels adjustments in Photoshop.

Please see image B for an animation comparing my image to that of the Hubble Space Telescope.

Target Description
M51 is about 25 million light years away and slightly smaller than the Milky Way in size.  It is an active, interacting, grand-design spiral galaxy. it is also a Seyfert galaxy, which means it has a high surface brightness and spectra show strong, high-ionization emission lines. It is believed that the strong spiral arms and the activity are due to the interaction with the dwarf galaxy NGC 5195, which is currently behind M51. Models suggest NGC 5195 has had multiple passes around M51 over hundreds of millions of years.  

The wonderful spiral arms and face-on view enabled William Parsons to be the first to see spiral arms in a nebula in 1845 through a 1.8 m telescope, though it wasn’t until Hubble used Cepheid variable stars to measure distances that it was realized that these nebulae were actually galaxies outside our own Milky Way galaxy.