Andy, have a look here:
http://galaxymap.org/cat/view/rcw/20
There seems to be some confusion about the nebulosity ID in this area. If you read the notes, it may be that Gum 11 = NGC 2579 but RCW 20 is different but in the same area.
Here is Geoff Scotts Astrobin image of the area, which has plate solving for the local DSOs.
http://www.astrobin.com/72126/
Obviously you have better detail of the nebulosity due to shooting Ha.