James Dunlop's handwritten notes are now available online at
https://nla.gov.au/nla.obj-112713379...obj-2611948293
This 447 page file describes the objects he found from Parramatta in 1826
J. Dunlop. Miscellaneous loose sheets (c. 360 ff), 1819 - 1826 (File 6)
On page 146 he says he moved to Mrs Elder's house on 7 March 1826
In his catalogue of clusters and nebulae he says he observed from 6" south and 1.78 seconds of time east of the Brisbane Observatory. That is from the red dot on this map
https://goo.gl/maps/ZW11vGskCETRnqKx5
A 1904 map shows that this land was owned by Mary Elder, James Dunlop and others. It was granted to them in 1841.
http://digital.sl.nsw.gov.au/deliver..._pid=IE3703467