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2. DUNLOP’S WORK IN AUSTRALIA 1821-1827
On May 18, 1821 Brisbane aged 47, Rümker 33 and Dunlop 27 sailed from England on the ship Royal George. They arrived in Sydney five-and-a-half months later on November 7, 1821, having sailed via Rio de Janeiro in Brazil.

Brisbane built his observatory next to Government House at Parramatta. It was completed in April 1822 but observations began on March 11, 1822 according to Dunlop's letter of resignation dated August 18, 1847.
(The Parramatta observatory was here. https://maps.app.goo.gl/RBaQJmaMryKL64289)

One year later on June 16, 1823 Rümker left the observatory after several disputes with Brisbane. Up to this time Rümker had observed between 2000 and 2300 stars. In the absence of Rümker, the untrained Dunlop continued making observations. Brisbane taught him to use the instruments and he completed A Catalogue of 7385 Stars, chiefly in the Southern Hemisphere (also called the Parramatta Catalogue) by March 2, 1826.

Dunlop prepared star maps of the Large Magellanic Cloud (which he called Nebula Major), the Small Magellanic Cloud (which he called Nebula Minor), and the area around Eta Carinae (which he called Eta Argus) using the mural circle. Dunlop also started work on his double star catalogue in 1825. Prior to this he made preliminary catalogues of clusters and nebulae in 1824.

Brisbane returned to England on December 1, 1825 via Cape Horn and Dunlop left the Parramatta Observatory on March 7, 1826, two months before Rümker returned to it on May 10, 1826. Dunlop moved to the Elder's house, it is now the southern part of the Woolpack Hotel on Marsden St, Parramatta.
(Dunlop lived here. https://maps.app.goo.gl/p3oUxK3BTwu3TfUQ7)

Dunlop spent March, 1826 watching a magnitude 6 comet (Comet Pons 1825 IV) from his observatory which was 50m SE of his home. The comet’s tail was 14 degrees long in Oct 1825. After this he produced two catalogues, the first of 629 clusters and nebulae and the second of 253 double stars. Dunlop worked on the double star catalogue when the moon was bright. Full moons in 1826 occurred on April 22, May 22, June 20, July 19, August 18, September 16, October 16 and November 15. Concurrently he worked on the non-stellar catalogue when it was clear and the moon was not up between April 27 and November 30, 1826.

He started his deep sky catalogue on April 27 when he observed four open clusters NGC 3532, IC 2714, Mel 105 and NGC 3766. Herschel missed two of these four objects and many others that Dunlop saw. Dunlop catalogued the Small Magellanic Cloud (SMC) on four nights between August 1 and September 6. The Large Magellanic Cloud (LMC) was studied on seven nights between August 3 and November 6. He found three galaxies on November 24, namely NGCs 1317, 1350 and 1365. On his last night, November 30 1826, he saw the faint globular cluster NGC 2298.

Dunlop used a 9-inch aperture, 9-foot long reflecting telescope that he made himself and a 3.25” aperture achromatic telescope of 46 inches focal length. The 9-inch speculum reflector had a magnitude limit of approximately 13 (similar to a modern 6” reflector) and a very poor resolution of about 5 arc-seconds.