Messier 106

Discovered by Pierre Méchain in July 1781.
Independently rediscovered by William Herschel on March 9, 1788.

Méchain: M106.

(in his letter to Bernoulli, May 6, 1783)
In July 1781 I found another nebula close to the Great Bear [Ursa Major] near the star No. 3 of the Hunting Dogs [Canes Venatici] and 1 deg more south, I estimate its right ascension 181d 40' and its northern declination about 49d. I will be going to determine the more acurate position of this one shortly.

William Herschel: H V.43.

V.43. March 9, 1788.
v brilliant. BN. with Fm. bran. np sf. 15' l. and to the sf. running into vF. nebulosity extending a great way. the N. is not R.
Very brilliant. Bright Nucleus. With faint milky branches north preceding and south following. 15' long and to the south following running into very faint nebulosity extending a great way. The nucleus is not round.

John Herschel (1833): h 1175.

h h 1175 = H V.43.
Sweep 330 (March 8, 1831)
RA 12h 10m 30.8s, NPD 41d 45' 18": (1830). [Right Ascension and North Polar Distance]
vB; vL; vsvmbM to an oval nucl; 8 or 9' long, 4 or 5' broad. (See fig. 55.)
Very bright; very large; very suddenly very much brighter toward the middle to an oval nucleus; 8 or 9' long, 4 or 5' broad. (See fig. 55.)

Sweep 255 (April 26, 1830)
RA 12h 10m 32.7s, NPD 41d 46' 19": (1830).
vB; vL; vsbM to an oval nucleus which is not in the middle of its length; 6'l, 3'br.
Very bright; very large; very suddenly brighter toward the middle to an oval nucleus which is not in the middle of its length; 6' long, 3' broad.

Sweep 329 (March 7, 1831)
RA 12h 10m 32.7s, NPD 41d 44' 6":: (1830).
vB; vL; sbM to a *; 6'l, 4'br.
Very bright; very large; suddenly brighter toward the middle to a star; 6' long, 4' broad.

Sweep 256 (April 27, 1830)
RA 12h 10m 32.7s, NPD 41d 46' 56":: (1830).
vB; L; vmE.
Very bright; large; very much extended [elongated].

[Appendix]

[Figure on Plate XIV, Figure 55, No. 1175, V. 43, RA 12h 10m 33s, NPD 41d 46']
Plate XIV. Figs. 50 .... 67. [includes I.43 (M104), V.8 (NGC 3628), V.1 (NGC 253), M65, h 875 (M66?), V.43 (M106), I.156 (NGC 1023), I.210 (NGC 4346), IV.42 (NGC 676), I,109 (NGC 1201), II.600 (NGC 7640), II.280 (NGC 2695), IV.30 (NGC 4861), I.55 (NGC 7479), IV.2 (NGC 2261), IV.66 (NGC 2701), III.602 (NGC 4571), and I.143 (NGC 4900)] - Long nebulae. The general form of elongated nebulae is elliptic, and their condensation towards the centre is almost invariably such as would arise from the superposition of luminous elliptic strata, increasing in density towards the centre. [..]

Smyth: CCCCXLI [441]. H V.43 [M106].

CCCCXLI. 43 H. V. Ursae Majoris [now Canum Venaticorum].
AR 12h 11m 04s, Dec N 48d 11'.1
Mean Epoch of Observation: 1837.26 [Apr 1837]
A large white nebula, closely following the haunches of the Greater Bear, discovered by WH [William Herschel] in 1788, and No. 1175 of his son's Catalogue. It is a noble-sized oval, trending rather from the vertical in a direction np [north preceding, NW] and sf [south following, SE], with a brightish nucleus in its southern portion; the lateral edges are better defined than the ends. It is preceded by two stars of the 10th magnitude, and followed by two others; and there are also some minute points of light in the field, seen occasionally by glimpses.
This object was carefully differentiated with Alkaid; and its place will be indicated by a running diagonal line across the square of Ursa Major, from Alpha through Gamma, and carrying it 7 1/2 deg into the south-east, that is, a little less than the distancebetween those stars.

Lord Rosse

John Herschel, General Catalogue: GC 2841.

GC 2841 = h 1175 = H V.43.
RA 12h 12m 1.7s, NPD 41d 55' 40.6" (1860.0) [Right Ascension and North Polar Distance]
vB; vL; vmE 0deg; sbMBN 8 observations by W. & J. Herschel.
Very bright; very large; very much extended in position angle 0 degrees; suddenly much brighter toward the middle where there is a nucleus.
Remark: Figure in P.T. 33 [John Herschel 1833], plate vi, fig. 55.

Huggins

[Further Observations on the Spectra of some Nebulae, with a Mode of determining the Brightness of these Bodies. Phil. Trans. Roy. Soc., Vol. 156 (1866), p. 381-397; here p. 389]
[No. [GC] 2841. 1175 h. 43 H. V. R.A. 12h 12m 1s.7. N.P.D. 41d 55' 40".6. Very bright; very large; suddenly brighter in the middle; bright nucleus.]
"A very large bright extended nebula; much mottled" - Lord Rosse
Spectrum continuous. A suspicion of unusual brightness about the middle part of the spectrum.

Dreyer: NGC 4258.

NGC 4258 = GC 2841 = h 1175 = H V.43.
RA 12h 12m 2s, NPD 41d 55.1' (1860.0) [Right Ascension and North Polar Distance]
vB, vL, vmE 0deg, sbMBN; = M106
Very bright, very large, very much extended in position angle 0 degrees, suddenly much brighter toward the middle where there is a nucleus.
Remark: Figure in P.T. 33 [John Herschel 1833], plate XIV, fig. 55.

Curtis

[Descriptions of 762 Nebulae ans Clusters photographed with the Crossley Reflector. Publ. Lick Obs., No. 13, Part I, p. 9-42]
NGC 4258, RA=12:14.0, Dec=+47:52. [Publ. Lick Obs.] Vol. VIII, Plate 33. With the very faint extensions this spiral is nearly 20'x6' in p.a. 165deg; very bright, elongated nuclear portion, on the west of which a short dark lane; there are numerous almost stellar condensations in the two principal spiral branches. See Abs. Eff. 11 s.n.

Helen B. Sawyer [Hogg]: Identification of M106

[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. .."