William Herschel discovered NGC 5857 = H II-751 = h1905, along with NGC 5859, on 27 Apr 1788 (sweep 834) and recorded "Two, the 1st [NGC 5857] cF, cS. The 2nd pF, pL, both lE." The next night he observed the pair again (sweep 835) and noted "both E from np to sf, but nearer the parallel." John Herschel logged and sketched (fig. 77) "a double nebula; pos of the individuals, centre from centre, 20° np; 2' dist."

A series of observations were made at Birr Castle of the pair. On 28 Apr 1848, Lord Rosse noted "[I] think the distance between the 2 neb greater than h's drawing." On 11 Apr 1850 George Stoney remarked "the two nebulae not in a line and a faint connection suspected." On 17 Apr 1855, R.J. Mitchell recorded "these two nebulae are not in a line, but run parallel to one another in the direction of the major axis, dist between them considerable, but faint neby suspected connecting them. On 9 May 1861, Samuel Hunter commented "bright brightest parts of both are elongated and not parallel to each other nor in the same straight line, but as shown [sketch included in the LdR 1861 publication]."

400/500mm - 17.5" (4/4/92): fairly faint, fairly small, elongated 2:1 NW-SE, bright core. Forms a striking close duo with NGC 5859 2.1' ESE with identical position angles.

Notes by Steve Gottlieb