Annnd we have a winner. Congratulations Gerns. You're art piece will be displayed as the facebook cover.
Though I notice that on Facebook the image has been blurred severely and letterboxed. I've made another version of my submission if you'd prefer to use it, which should meet the height dimensions on the Facebook cover. I'm not sure why that's been blurred, since it didn't seem to need resizing. I hope this version will fix that and look cleaner!
For me to get the full image in there, I had to add some height. I don't have time right now to put this one on, as I am getting ready to leave for the day. When I get back this evening evening, it'll be my first priority
EDIT - never mind, I did it. Fits perfectly!