I think I have finally collected enough data to show the extended halo of M83. I have found this particularly interesting because there appears to be a distinct corridor that is cleared by the galaxy on the right hand side from about 12 o'clock to 9 o'clock. At first I thought like a few others have mentioned that it might be flats related. However I have hunted around on the net a little and found several other images from prominent astrophotographers that show a similar thing. Unfortunately the tidal stream would take a look more integration to show up in the full frame (this being a crop to minimise field curvature).
I decided at one point to start collecting Ha data too. The galaxy is filled with Ha light. I have subsequently added Ha and further collected luminance. Total integration is now 23 hours. I think that is enough.
Figure 5. Even well-known galaxies can spring surprises. This deep image of M83 reveals an enormous loop around the NW quadrant of the galaxy. The inset image is the same scale as the main picture. The scale bar is 30 arc min.
Magnificent work, Paul. The halo is shown beautifully. The colour is superb. Detail right to the core.
The right-most of the two little galaxies at 10 o'clock shows very faint outer spiral arms as a distant circle. Trish and I had seen that in our M83, but it is clearer in yours.
A real monster of a galaxy and a worthy picture Paul. Looks good enough to eat!!
The small BG galaxies at 9 o clock- are they related in anyway to M83? If so how haven't they been sucked into that monster's gravity well?
And if they are true background, would it be possible to detect gravitational lensing on them from M83? (just thinking out loud so may be totally barking up the wrong light pole again)
Anyway - another classic- extremely well done.
Graz
JK 
