Messier 83 (also known as the Southern Pinwheel Galaxy, M83 or NGC 5236) is a barred spiral galaxy approximately 15 million light-years away in the constellation Hydra. It is one of the closest and brightest barred spiral galaxies in the sky, making it visible with binoculars. Six supernovae (SN 1923A, SN 1945B, SN 1950B, SN 1957D, SN 1968L and SN 1983N) have been observed in M83.
The above text is taken from Wikipedia.
Mouseover of the small thumbnails to the left will show the three different images.
LRGB: Just a plain LRGB combination.
Ha enhanced LRGB: Ha was added to the Red channel by the PS blend mode lighten and by masking of the background (to maintain a neutral background) before construction the LRGB
Annonated Ha enhanced LRGB: Shows the Ha enhanced image with a grid overlay and known objects marked. It was created in PixInsight using the scripts ImageSolver (a plate solve) AnnonateImage (adding the object names and grids).
The following software has been used. ACP (image acquisition and guiding), CCDStack (calibration and RGB scaling, PixInsight (cropping, background correction, colour corrections) and Photoshop CS5 (all the rest, incl Noel Carbonis Astronomy Tools).
This image was processed in April 2012