Had a lot of trouble processing this one, but I think I finally nailed it. Very hard to get down to the core and still show the halo.
http://www.astrobin.com/102715/B/
Telescope: Plane Wave 12.5" CDK
Mount: AP900
Camera: QSI540wsg
Exposure:90min each of R, G, B binned 2 x 2, 90 min L bin 1. All at 10min subframes.
Processing: PixInsight
Geoff