Messier 68

Discovered on April 9, 1780 by Charles Messier.

Messier: M68.

April 9, 1780. 68. 12h 27m 38s (186d 54' 33") -25d 30' 20"
`Nebula without stars below Corvus & Hydra; it is very faint, very difficult to see with the refractors; near it is star of sixth magnitude.'

William Herschel

[PT 1814 p. 273, SP2 p. 534]
Connoiss. 68 [M 68 = NGC 4590] is "A beautiful cluster of stars, extremely rich, and so compressed that most of the stars are blended together; it is near 3' broad and about 4' long, but chiefly round, and there are very few scattered stars about."
This oval cluster is also approaching to the globular form, and the central compression is carried to a high degree. The insulation is likewise so far advanced that it admits of an acurate description of the contour.

[PT 1818 p. 446, SP2 p. 600]
The 68th of the Connoissance. [M 68 = NGC 4590]
"1786, 1789, 1790, 20 feet telescope. A cluster of very compressed small stars, about 3 minutes broad and 4 minutes long. The stars are so compressed, that most of them are blended together."
Probably the stars of this cluster might be perceived by a 10 feet telescope, so that the profundity may be of the 344th order.

Smyth: CCCCLIV [454]. M68.

CCCCLIV. 68 M. Hydrae.
AR 12h 30m 56s, Dec S 25d 51'.1
Mean Epoch of Observation: 1837.25 [April 1837]
A large round nebula on Hydra's body, under Corvus, discovered in 1780 by Méchain [actually Charles Messier]. In 1786, Sir William Herschel's powerful 20-foot reflector resolved it into a rich cluster of small stars, so compressed that most of the components are blended together. It is about 3' broad, and 4' long; and he estimated that its profundity may be of the 344th order. It is posited nearly mid-way between two small stars, one in the np [NW] and the other in the sf [SE] quadrant, a line between which would bisect the nebula. It is very pale, but so mottled that a patient scrunity leads to the inference, that it has assumed a spherical figure in obedience to attractive forces. Differentiated with Beta Corvi, from which it bears south by east, within 3 deg distance.

John Herschel (1847): h 3404.

h 3404 = M. 68.
Sweep 689 (March 22, 1836).
RA 12h 30m 30.1s, NPD 115d 48m 50s (1830.0) [Right Ascension and North Polar Distance]
Glob. Cl.; irr R; g b M; diam in RA = 12...15 sec. All clearly resolved into stars 12 m; very loose and ragged at the borders.
Globular Cluster; irregularly round; gradually brighter toward the middle; diameter in RA = 12...15 sec [3.0 .. 3.75']. All clearly resolved into stars of 12 m; very loose and ragged at the borders.

John Herschel, General Catalogue: GC 3128.

GC 3128 = h 3404 = M68.
RA 12h 32m 5.1s, NPD 115d 58' 45.2" (1860.0). [Right Ascension and North Polar Distance]
Glob. Cl.; L; eRi; vC; iR; rrr; st 12, red. 4 observations by W. & J. Herschel.
Globular cluster; large; extremely rich; very compressed; irregularly round; well resolved; stars of 12th magnitude, red.

Dreyer: NGC 4590.

NGC 4590 = GC 3128 = h 3404; M 68.
RA 12h 32m 5s, NPD 115d 58.8' (1860.0). [Right Ascension and North Polar Distance]
Glob. Cl., L, eRi, vC, iR, rrr, st 12; = M68
Globular cluster, large, extremely rich, very compressed, irregularly round, well resolved, stars of 12th magnitude.