197 Years Ago
It was a clear Thursday night the 27 April 1826 in Parramatta, NSW. James Dunlop’s 9” (23cm) aperture homemade speculum reflector was aligned and pointing exactly south. It was located halfway between Marsden St and Church St about 70m south of George St. His ladder was ready for him to climb up to the eyepiece of the 9’ (274cm) long tube. An oil lamp burned dimly on a table and his pen and paper were ready to record his first night’s observations. The sunset at 5:20pm and he waited eagerly for astronomical twilight to end at 6:45pm.
Dunlop started sweeping his telescope back and forth from north to south along the meridian. At 8:35pm a large open cluster appeared in his low power 45’ field. It was not a new object. Lacaille had discovered it in 1751 and it is now called NGC 3532. He recorded the sidereal time from the pendulum clock, the object’s south polar distance (its altitude was 62 degrees) and a description, then he kept searching back and forth.
Another open cluster came into view at 8:46pm. It was a new discovery, now called IC 2714. Just 3 minutes later he discovered another cluster 46’ away, now called Mel 105. John Herschel missed these two clusters when he swept the sky from Cape Town between 1834 and 1838, and they were not included in the NGC catalogue in 1888. At 9:05pm Dunlop found the nights 4th open cluster. It was another Lacaille object, now called NGC 3766.
The 66% sunlit Moon rose at 10pm and Dunlop retired to his room at the Elder’s house, satisfied with his first night sweeping the southern sky for clusters and nebulae. James and Mary Elder were fellow Scots and their house is now part of the Woolpack Hotel.
https://goo.gl/maps/VcnLmgwva6g4obaV8
The attached 1844 map shows the location of the Elder's house and a red D shows the location of Dunlop's telescope.