[sjastro]

Thanks for your comments Mike.

The large halos in my image are mainly caused by the application of a star mask that was too large for the star. Stretching the image results in everything but the region underneath the mask being stretched.

Of greater concern was the alternating brightness variation as one moves away from the disk of the galaxy.
This was caused by an incompatibility between the skyglow subtraction routine and the non linear stretching.
I believe I have fixed this problem by modifying the routine.

At this stage I have sent Olivier a revised version without the skyglow subtraction routine. The halos and brightness variations are gone but the galaxy halo is not as conspicuous as in the original image.
I suspect ESO will measure the pixel values from the edge of the disk to the edges of the frame. A drop off in the pixel values down to the background noise is probably a strong indication the outer halo is real.

If this is the case the next step would be to submit an image where the skyglow has been subtracted.

The interesting point in the discussions with Olivier is the "cultural differences" between amateur astroimagers and their professional counterparts.
We amateurs convey information through the visual presentation of our images, the professional on the other hand extracts quantitative information from the image.
The more we amateurs process an image, the less useful information is available. This was certainly the case when I performed a noise reduction on the image!

Hopefully this exercise will conclude where an image of an obvious extended halo is found to be real and is backed by scientific information.

Regards

Steven