What makes you think it is nobbi? They are difficult to tell from muricatus and unless I can see, or you record a pink inside mouth colour rather than bright yellow or a pink/red flush to the base of the taiI, I would be reluctant to call it nobbi..Even though it does have an unusual back pattern there is nothing in this image to be sure. Other comments welcome here!
Hi, I was simply guessing from the pattern on its back compared to a couple of photos I saw. I didn't see the inside of its mouth. So I'm happy to call it muricatus if that's the more likely identity.
I agree with JW this is a A. muricatus - the female nobbi dragons can look quite like an A. muricatus but the pattern of your individual is pretty typical of muricatus. Because the photograph is a bit out of focus? hard to see the enlarged spinous scales that would help us out further. What I can add is that I live in Western Creek and for about 20 years i have walked regularly at Mt Stromlo including that far western side and never saw a nobbi dragon in that part of the ACT. The only records i know of near here are along the slopes of the Murrumbidgee River. Having said that it is great that you made a stab at the id and drew it to our attention. WillO