John Herschel discovered NGC 2666 = h525 on 19 Mar 1828 (sweep 139) and simply noted "The chief * of a coarse cluster." He made no mention of size, but there are no other objects matching his description nearby. Karl Reinmuth remarked "nothing like a cluster" in his NGC photographic survey based on Heidelberg plates.

In Jun 2016 Harold Corwin checked JH's sweep record again and found "JH accidentally copied the reduced NPD of the preceding object in the sweep (a double star) into the column for the reduced NPD of this cluster. The difference in the NPD index between the two objects is 2d 21' 18", leading to a corrected position for JH's "chief *" of 08 38 14.8, 44 40 27 (NPD, 1830) or 08 49 49, +44 42.3 (J2000), very close to the position of the SAO star. The identity of JH's object with the sparce group is no longer in any doubt."

400/500mm - 18" (2/14/10): The HD 751354 group consists of nearly two dozen stars scattered around a mag 8 star. Three collinear stars (length 3') oriented SW to NE are 2' E of HD 75135. Another group of ~10 stars is scattered over a 5' region to the NW of the bright star. This group was visually uninspiring and appears to be an asterism.

18" (2/23/06): the only possible candidate near John Herschel's original position is a mag 11.7 star and a group of five mag 13.5-14.5 stars close south. Four of the stars are strung along a 5' gently curving arc. To the northeast is a much brighter 10' string of a half dozen stars that extends towards the northeast. Neither of these asterisms, though, are probably eye-catching enough to be mentioned as a "course cluster". Note: Based on more recent historical investigation, this identification is incorrect.

Notes by Steve Gottlieb