More likely, though, NGC 1840 is a duplite of NGC 1833.

John Herschel discovered NGC 1840 = h2771 on 3 Nov 1834 and described "F, R, bM, resolvable. Hardly visible through a thick haze. The observations makes the RA 6m 13.5s, but this is impossible from the context [of the sweep]. It may be 8m." In the Cape observations, Herschel gives a position of 5h 7m 13.5s (1830), which is ~3' too far west, and that position is also used in the GC. In any case, the only nearby object is an asterism of 4 stars.

Eric Lindsay, in the 1964 paper "Some NGC objects in the Large Magellanic Cloud", comments "There is some confusion about the RA. Dreyer chose the position 5h 6m 13.5' (1830) instead of 5h 7m 13.5s adopted by Herschel. There is nothing at either position. The object was hardly visible though a thick haze, the observation made the RA 6m which was considered impossible and may even by 8m. At the latter is the small cluster S/L 235."

In August 2016 Harold Corwin went over the sweep carefully and concluded "Checking this arc, we find two candidate objects: NGC 1833 and SL 249 (at

05 07 35, -70 44.9). The NGC object (= h 2765) is the larger and brighter of the two, and its position is off JH's by even digits: 1 minute of time, and 1 degree of declination. This makes it likely to also be NGC 1840."

600/800mm - 30" (10/15/15 - OzSky): NGC 1840 may the asterism of four mag 13.7-14.7 stars within 1.4' at this position. In addition a couple of mag 15-16 stars were resolved at 394x. Situated in a sparsely populated field.

Notes by Steve Gottlieb