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[M 92]

Messier 92

Observations and Descriptions

Discovered on December 27, 1777 by Johann Elert Bode.
Independently rediscovered by Charles Messier on March 18, 1781.

Messier: M92.
March 18, 1781. 92. 17h 10m 32s (257d 38' 03") +43d 21' 59"
Nebula, fine, distinct, & very bright, between the knee & the left leg of Hercules, it can be seen very well in a telescope of one foot [FL]. It contains no star; the center is clear & brilliant, surrounded by nebulosity & [it] resembles the nucleus of a large Comet: its brightness, its size, approach much that of the nebula which is in the girdle of Hercules. See No. 13 of this Catalog: its position has been determined, by direct comparison with the star Sigma Herculis, fourth magnitude: the nebula & the star are on the same parallel. (diam. 5')

Bode: Bode 76.
A nebula. More or less round with pale glow.
On this occasion, I also want to announce that on December 27, 1777 I have discovered a new nebula in Hercules, not known to me, southwest below the star s in his foot, which shows up in a mostly round figure with a pale glimmer of light. Its longitude is about 11 deg [Sgr] [251 d] and its latitude 66d north.Together with two small [faint] stars, which don't occur at Flamstead, it appears in the reversing telescope as shown in fig k (in the following volume).

William Herschel
[PT 1818 p., reprinted in Scientific Papers, Vol.2, p. 601]
The 92nd of the Connoissance des Temps.
"1799, 7 feet finder. It may just be distinguished; it is but little larger than a star."
"1783, 2 feet sweeper. With 15 it appears like a clouded star."
"1783, 7 feet telescope.With 227 resolves into very small stars; with 460 I can count many of them."
"1799, 10 feet telescope. With 240 the stars are much condensed at the centre."
"1783, 1787, 1799, 20 feet telescope. A brilliant cluster, 6 or 7 minutes in diameter."
"1805, large 10 feet telescope. The most condensed part is 3'16" in diameter."
The profundity of this cluster, by the observation with the 7 feet telescope, is of the 243rd order.

Smyth: DCXI [611]. M92.
DCXI. 92 M. Herculis.
AR 17h 12m 14s, Dec N 43d 18'.4
Mean Epoch of Observation: 1835.56 [July 1835]
[with drawing]
A globular clusterof minute stars, preceding the right leg of Hercules. This object is large, bright, and resolvable, with a very luminous centre; and, under the best vision, has irregular streamy edges. It is immediately preceded by a 12th-magnitude star, distinct from the outliers, and there are several other stars in the field, of which the brightest is of the 7th magnitude in the nf [north following, NE], with a Delta AR = 28s. Messier, who enrolled it in 1781, remarks that "it is easily seen with a telescope of one foot [FL];" and it really demands very little optical aid to render it visible. Messier's own instrument did not, it seems, resolve it, for he compares the shining centre, with its attendants, to the nucleus of a comet surrounded by nebulous matter; but of course, it rose into a brilliant cluster, of 7' or 8' in diameter, before the reflectors of Sir W. Herschel in 1783. The mean place was obtained by carefully differentiating the cluster with Eta Herculis, from which it bears north-by-east, 1deg 1/2 distant; bearing to the north of Alpha Herculis, and west of Wega.

John Herschel, General Catalogue: GC 4294.
GC 4294 = M92.
RA 17h 12m 56.9s, NPD 46d 43' 31.2" (1860.0) [Right Ascension and North Polar Distance]
Glob. Cl.; vB; vL; eCM; rrr; st S. 8 observations by W. & J. Herschel.
Globular cluster; very bright; very large; extremely compressed toward the middle; well resolved; small [faint] stars.
Remark: 4294. M92 (= also Lalande No. 31544). Not observed by h [JH], but 8 times by H [WH]. Place from Wollaston's catalogue, which is almost identical with Auwers (difference in RA = 0.1s, in PD = 0' 3").

[from Phil. Trans. Vol. 154 (1864), p. 437-444, here p. 441]
[No. [GC] 4294. 92 M. R.A. 17h 12m 56s.9. N.P.D. 46d 43' 31".2] In Hercules. Very bright globular cluster of stars. The bright central portion was brought upon the slit. A faint spectrum similar to that of a star. The light could be traced from between [Fraunhofer line] C and D to about G.

Dreyer (1877)
Vol. VIII of the Annals of the Observatory of Harvard College, which was received at Birr Castle in the summer 1877, contains lithographs from drawings by Mr. Touvelot of the following Nebulae: GC 116 [M 31] (Pl. 33), 1179 [M 42] (Pl. 24, Woodbury type), 4230 [M 13] and 4294 [M92] (Pl. 25), 4355 [M20] (Pl. 32), 4447 [M57] (Pl. 34), 4532 [M27] (Pl. 35).

Dreyer: NGC 6341.
NGC 6341 = GC 4294; M 92 = Lalande 31544.
RA 17h 12m 51s, NPD 46d 42.6' (1860.0) [Right Ascension and North Polar Distance]
Glob. Cl., vB, vL, eCM, rrr, st S; = M92
Globular cluster, very bright, very large, extremely compressed toward the middle, well resolved, small [faint] stars.
Remark: Figures in H.C. [Winlock and Trouvelot, Annals of Harvard College Observatory, vol. vii], plate 25; Schultz [Schultz, Mikrom. Bestimmung einiger teleskopischen Sternhaufen (Bihang til K. Svenska Vetensk. Akad. Handl, xii, 1886)], plate II.

[Descriptions of 762 Nebulae ans Clusters photographed with the Crossley Reflector. Publ. Lick Obs., No. 13, Part I, p. 9-42]
NGC 6341, RA=17:14.1, Dec=+43:15. Bright, unusually condensed globular cluster; cluster about 10' in diameter; the bright central portion 2'. M. 92. 24 s.n.
  • Observing Reports for M92 (IAAC Netastrocatalog)

    Hartmut Frommert
    Christine Kronberg

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    Last Modification: February 20, 2005