Messier 107

Discovered by Pierre Méchain in April 1782.
Independently rediscovered by William Herschel on May 12, 1793.

Méchain: M107.

(in his letter to Bernoulli, May 6, 1783)
In April 1782 I discovered a small nebula in the left flank of Ophiuchus between the stars Zeta and Phi, the position of which I have not yet observed any closer.

William Herschel: H VI.40.

VI.40. May 12, 1793.
A very beautiful e com. cl. of st. extremely rich, 5 or 6' in diam. gradually more compressed toward the centre.
A very beautiful extremly compressed cluster of stars, extremely rich, 5 or 6' in diameter, gradually more compressed toward the centre.

Smyth: DLXXIX [579]. H VI.40 [M107].

DXCV. 40 H. VI. Ophiuchi.
AR 16h 23m 35s, Dec S 12d 41'.1
Mean Epoch of Observation: 1837.38 [May 1837]
A large but pale granulated cluster of small stars, on the Serpent-bearer's right leg. There are five telescopic stars around it, so placed as to form a crucifix, when the cluster is high in the field; but the region immediately beyond is a comparative desert. After long gazing, this object becomes more compressed in the centre, and perplexes the mind by so wonderful an aggregation. It was discovered by WH in May, 1793, and was registered 5' or 6' in diameter. The mean place was obtained by differentiation with Zeta Ophiuchi, from which it is distant 3deg to the south-south-west, in the line between Beta Scorpii and Beta Ophiuchi.

John Herschel (1847): h 3637.

h 3637 = H VI.40 [M107].
Sweep 702 (Jun 5, 1836).
RA 16h 23m 2.5s, NPD 102d 40m 17s (1830.0) [Right Ascension and North Polar Distance]
Glob. Cl.; v rich; g p m b M; diam in R.A. = 20.0s; that of the most comp part 4.5s; stars well saparated.
Globular Cluster; very rich; gradually pretty much brighter toward the middle; diameter in R.A. = 20.0s [5']; that of the most compact part 4.5s [1.1']; stars well saparated.

John Herschel, General Catalogue: GC 4211.

GC 4211 = h 3637 = H VI.40. Mechain.
RA 16h 24m 43.0s, NPD 102d 44' 17.3" (1860.0) [Right Ascension and North Polar Distance]
Glob. Cl.; L; vRi; vmC; R; rrr. 2 observations by W. & J. Herschel.
Globular cluster; large; very rich; very much compressed; round; well resolved.

Dreyer: NGC 6171.

NGC 6171 = GC 4211 = h 3637 = H VI.40. Méchain.
RA 16h 24m 42s, NPD 102d 44.8' (1860.0) [Right Ascension and North Polar Distance]
Glob. Cl., L, vRi, vmC, R, rrr; = M107
Globular cluster, large, very rich, very much compressed, round, well resolved.

Curtis

[Descriptions of 762 Nebulae ans Clusters photographed with the Crossley Reflector. Publ. Lick Obs., No. 13, Part I, p. 9-42]
NGC 6171, RA=16:27.0, Dec=-12:50. Bright globular cluster; the brighter part is 3' in diameter; with fainter extensions about 8'. 2 s.n.

Helen B. Sawyer [Hogg]: Identification of M107

[in Astronomical Journal, Vol. 53, p. 117 (1948)] ".. a long-overlooked letter by Pierre Méchain was found in Bode's Jahrbuch for 1786. .. He also lists four nebulae which he has discovered, and these should logically be given Messier numbers as follows: NGC 4594 as M104; NGC 3379 as M105; NGC 4258 as M106; and NGC 6171 as M107. .."