10x30mm Canon IS (3/28/19 - Tasmania): easy naked-eye cluster in a gorgeous wide-angle binocular field! Situated within a superb string of bright stars. Very bright, high surface brightness cluster with a few resolved stars, moderately large and well defined. A few additional stars popped on and off.

Nicolas-Louis de Lacaille discovered NGC 3766 = Lac III-7 = D 289 = h3352 in 1751-1752 with a 1/2-inch telescope at 8x during his expedition to the Cape of Good Hope. He noted "three faint stars in nebulosity". James Dunlop observed the cluster on 27 Apr 1826 (first night logging objects) 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." Dunlop's position was about 10' too far SE.

John Herschel first observed the cluster on 14 Mar 1834 and noted "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."

300/350mm - 13.1" (2/18/04 - Costa Rica): this is a superb naked-eye open cluster in Centaurus with several hundred stars resolved in a 15' field. It contains a very dense mass of stars in the central 5' that are seemingly arranged in a spiral configuration as well as a beautiful string of stars running SW-NE on the south side of the cluster. A mag 7.2 M-type reddish star (SAO 251470) lies at the NW end, a mag 7.5 star is on the east side (HD 306799) and a mag 7.1 star (HD 100943) is on the SE side. On the N end is B798, a mag 9.1/9.4 pair at 5" separation. This impressive cluster was a surprising showpiece as it wasn't on my radar as an excellent cluster. Located 50' NW of a mag 5.1 star and 1.4° due north of mag 3.1 Lambda Centauri.

Notes by Steve Gottlieb