It can be hard to separate D. nobbi from A. muricatus - particularly in a photograph. So you were correct in wondering which species it was that you had photographed. The colour of the inside of the mouth would have helped as Nobbi Dragons have pink mouths and Jacky Lizards have yellow mouths. Because this individual resembles many Tree Dragons that have been seen and photographed in the ACT, and because it is well away from known nearest records along the Murrumbidgee Corridor we can be reasonably confident it is a A. muricatus. Thanks for your record from an interesting location.