History

This open cluster was discovered by French astronomer Nicolas-Louis de Lacaille in 1751-1752 using a ½-inch telescope at 8x during his expedition to the Cape of Good Hope. He listed it as Lac III-7 and noted: «Three faint stars in nebulosity.» ^[8]

Scottish astronomer James Dunlop observed the cluster five times in 1826-1827 using his 9-inch reflecting telescope at his home in Parramatta (NSW) in Australia. He listed the cluster as Δ 289 and noted: «A pretty large cluster of stars of mixt magnitudes, about 10' diameter. The greater number of the stars are of a pale white colour. There is a red star near the preceding side; another of the same size and colour near the following side; another small red star near the centre; and a yellow star near the south following extremity, all in the cluster.» ^[50]

John Herschel listed the cluster as h 3352 and observed it two times using his 18.3-inch reflector at South Africa. Sweep 432 (14 March 1834): «The preceding of two chief stars of a fine, large, loose, round cluster of stars 8..12th mag; gradually pretty much brighter in the middle, fills field; 150..200 stars.» Two sweeps later he recorded: «A very fine cluster class VII; nearly round, 8' diameter, slightly compressed in the middle, stars of 9..15th magnitude; place that of an orange star 9..10th mag following the centre.» ^[11]