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.
Click here for larger resolution image.
Feel free to comment.