Messier 93

Discovered on March 20, 1781 by Charles Messier.

Messier: M93.

March 20, 1781. 93. 7h 35m 14s (113d 48' 35") -23d 19' 45"
Cluster of small stars, without nebulosity, between the Greater Dog [Canis Major] and the prow of the ship [Puppis of Argo Navis]. (diam 8')

Caroline Herschel: No. 1.

No. 1
Febr 26th [17]83. Nebula, about 1 1/4 deg north preceding the bright star in the Ship [or more exactly] preceding the 1st Navis [Puppis] towards 23 Canis majoris. My Brother examined it with [magnification] 460 and found not less than 20 stars, with 227 above 40. with a compound eyepiece perhaps 100 and 150 very beautiful, nothing nebulous among them. Messier has it not.
[Hoskin (2005) cites Owen Gingerich for figuring out a mistake in this description, that 1 (Rho) Navis - which is porbably too far south to have been seen by Caroline - should probably read 7 (Zeta) Navis [Puppis]. Then the description acurately matches M93. - hf]

William Herschel:

[Unpublished Observations of Messier's Nebulae and Clusters. Scientific Papers, Vol. 2, p. 660]
1784. Apr. 8 (Sw. 187). pL. [pretty large], with a nucleus, perhaps cometic, but moonlight permits not to give a proper description.
1784. Apr. 17 (Sw. 199). pL. [pretty large].

Smyth: CCCVII [307]. M93.

CCCVII. 93 M. Argo Navis [now Puppis].
AR 7h 37m 44s, Dec S 23d 29'.1
Mean Epoch of Observation: 1836.13 [February 1836]
A small galxy cluster [open star cluster in the band of the Milky Way], in the aplustre of the Argo's poop [Puppis]; a line from Orion's sword-cluster, led through Sirius, strikes upon it 16deg beyond, where it will be intersected by a ray from Castor through Procyon. The neat proup is of a star-fish shape, the sp [south preceding, SW] portion being the brightest, with individuals of 7 to 12 magnitudes: it was first registered by Messier, in 1781, as a mass of small [faint] stars.
The unlucky Chevalier d'Angos, of the Grand-Master's observatory at the summit of the palace of Malta, mistook this cluster for a comet: from which, and some still more suspicious assertions, my excellent friend, Baron de Zach, was induced to term any egregious astronomical blunders - Angosiades.

John Herschel (1847): h 3098.

h 3098 [= M93].
Sweep 768 (January 31, 1837)
RA 7h 37m 22.9s, NPD 113d 28m 30s (1830.0) [Right Ascension and North Polar Distance]
A fine cluster, scarcely scattered, pretty rich, not much more comp[ressed]. M [toward the middle]. Nearly fills field. Stars 8....13 m.

John Herschel, General Catalogue: GC 1571.

GC 1571 = h 3098 = M93.
RA 7h 38m 39.2s, NPD 113d 32' 43.2" (1860.0) [Right Ascension and North Polar Distance]
Cl; L; pRi; lC; st 8...13. 2 observations by W. & J. Herschel.
Cluster; large; pretty rich; little compressed; stars from 8th to 13th magnitude.

Dreyer: NGC 2447.

NGC 2447 = GC 1571 = h 3098; M 93.
RA 7h 38m 39s, NPD 113d 32.7' (1860.0) [Right Ascension and North Polar Distance]
Cl, L, pRi, lC, st 8...13; = M93
Cluster, large, pretty rich, little compressed, stars from 8th to 13th magnitude.