Messier 104

Discovered by Pierre Méchain on May 11, 1781.
Independently rediscovered by William Herschel on May 9, 1784.

Messier: M104.

[May 11, 1781. 104.] 12h 28m 39s (187d 9' 42") -10d 24' 49"
(Messier's handwritten note in his copy of the Connoissance des Temps for 1784)
Very faint nebula, seen by M. Méchain on May 11, 1781.
[A position follows which agrees with Herschel's H I.43, according to Camille Flammarion, see below]

Méchain

(in his letter to Bernoulli, May 6, 1783)
On May 11, 1781, I discovered a nebula above the Raven [Corvus] which did not appear to me to contain any single star. It is of a faint light and difficult to find if the micrometer wires are illuminated. I have compared it [its position] on this day and the following with Spica in the Virgin and from this derived its right ascension 187d 9' 42" and its southern declination 10d 24' 49" [the same position as in Messier's handwritten note]. It does not appear in the Connoissance des Temps.

William Herschel: H I.43.

I.43. May 9, 1784. E. vBM. 5 or 6' l.
Extended [elongated]. Very bright toward the middle. 5 or 6' long.

[From: Notes to Sir W. Herschel's First Catalogue of Nebulae and Clusters, by J.L.E. Dreyer, in: Scientific Papers, Vol. 2, p. 295]
Second obs., Sw. 819, Mar. 11, 1788. mE, from about 20d sp. to nf., BN., 4 or 5' long, 49 Virg. p. 27m 45s s. 0d 51'. In 1784 "the B. place in the middle is pL., but breaks off abruptly."
Second observation, Sweep 819, Mar. 11, 1788. Much elongated, from about 20d south preceding [SW] to north following [NE], brighter toward the nucleus, 4 or 5' long, 49 Virg. preceding [W] 27m 45s, south 0d 51'. In 1784 "the bright place in the middle is pretty large, but breaks off abruptly."

John Herschel (1833): h 1376.

h 1376 = I.43.
Sweep 129 (March 9, 1828)
RA 12h 31m 10.9s, NPD 100d 40' 19" (1830.0) [Right Ascension and North Polar Distance]
vB; vmE, in pos 2deg np to sf, vsmbM to a nucleus; 5' l, 30" br, a B * sp. There is a faint diffused oval light all about it, and I am almost positive that there is a dark interval or stratum separating the nucleus and general mass of the nebula from the light above (s of) it. Surely no illusion. (See fig 50).
Very bright; very much elongated, in position angle 2deg north precedint [NW] to south following [SE]; very suddenly much brighter toward the middle to a nucleus; 5' long, 30" broad, a bright star south preceding. There is a faint diffused oval light all about it, and I am almost positive that there is a dark interval or stratum separating the nucleus and general mass of the nebula from the light above (south of) it. Surely no illusion. (See fig 50).

[Appendix]

[Figure on Plate XIV, Figure 50, No. 1376, I. 43, RA 12h 31m 11s, NPD 100d 40']
Fig. 37. V. 24 [NGC 4565], and Fig. 50. I. 43 [M104]. - The strong suspicion of a parallel appendage to the latter of these, is almost converted into certainty by its undoubted existence in [H] V. 24 [NGC 4565], in which it was seen by two other observers as well as by myself. But what are we to make of such an appendage? Must we consider it as an extreme exaggeration of the case of M. 64 (fig. 27), in which the vacancy is extended up to almost the very extremities of the elliptic outline, - in which case the nebula would come to be regarded as a flat annulus seen at a great obliquity, and having very unequal breadth and densities in its two opposite semicircles? Or must we admit the appendage to be a separate and distinct nebula, dependent, by some unknown physical relation, on its brighter neighbor?
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: CCCCLV. [455]. H I.43

CCCCLV. 43 H. I. Virginis.
AR 12h 31m 40s, Dec S 10d 43'.7
Mean Epoch of the Observation: 1837.25 [March 1837]
[with a drawing]
"A lucid white elliptical nebula, between the Virgin's right elbow and the Raven, in an elegant field of small stars; discovered by WH [William Herschel] in May, 1784, and No. 1376 in his son's Catalogue. It lies nearly parallel to the equatorial line of the instrument, and on intense attantion may be seen to blaze in the middle. The half dozen principal stars form a great Y, with the nebula as the centre. But it seems a mere wisp of subdued light, insomuch that my telescope does not afford me even the doubts inspired with the 20-foot reflector; for Herschel remarks that there is a faint, diffused oval light all about it, and that he is almost positive that there is a dark interval or stratum, separating the nucleus and the general mass of the nebula from the light above it. "Surely, no illusion."
"The general form of elongated nebulae is elliptic," says WH, "and their condensation toward the centre is almost invariably such as would arise from the superposition of luminous elliptic strata, increasing in density toward the centre." This must be another of those vast flat rings seen very obliquely, already spoken of, and is an elegant example of that celestial perspective; it bears due west from Spica, and is 11d distant from that star, forming nearly a right angle with Beta Hydrae, which lies 12d to the southward."

John Herschel, General Catalogue: GC 3132.

GC 3132 = h 1376 = H I.43.
RA 12h 32m 44.2s, NPD 100d 50' 14.2" (1860.0) [Right Ascension and North Polar Distance]
!; vB; vL; eE 92deg, vsmbMN. 3 observations by W. & J. Herschel.
Remarkable; very bright; very large; extremely extended toward position angle 92 deg; very suddenly much brighter toward the middle where there is a nucleus.
Remark: Figure in PT 1833 [J.H. 1833], plate vi, fig. 50.

Lassell

[Memoirs of the Royal Astronomical Society, Vol. XXXVI (36)]
[Drawing on Plate V, Fig. 22]

Dreyer (1877)

GC 3132, h. 1376 [M 104]. Drawings in Lassell, Plate V, Fig. 22.

Dreyer: NGC 4594.

NGC 4594 = GC 3132 = h 1376 = H I.43.
RA 12h 32m 43s, NPD 100d 51.2' (1860.0) [Right Ascension and North Polar Distance]
!, vB, vL, eE 92deg, vsmbMN; = M104
Remarkable, very bright, very large, extremely extended toward position angle 92 deg, very suddenly much brighter toward the middle where there is a nucleus.
Remark: Figures in PT 1833 [J.H. 1833], plate XIV, fig. 50; Lass. 2 [Lassell, Memoirs R.A.S. vol. xxxvi], plate V, fig. 22.

Curtis

[Descriptions of 762 Nebulae and Clusters photographed with the Crossley Reflector. Publ. Lick Obs., No. 13, Part I, p. 9-42]
NGC 4594, RA=12:34.8, Dec=-11: 4. 7'x1.5' in p.a. 92deg; very bright. A remarkable, slightly curved, clear-cut dark lane runs along the entire length to the south of the nucleus; probably the finest known example of this phenomenon. There are very slight traces of spiral whorls. See Abs. Eff. 11 s.n.

Flammarion: Identification of M104

[L'Astronomie, vol. 35, pp. 331-334 (August 1921), here p. 334. Announce of Méchain's discovery of M104, appended to his description of M103]
"The classic 1783 [actually 1784] edition of "Connaissance des Temps" concludes with this Messier 103; however, a note in my copy - which appears to be in Messier's own hand - contains these two lines, which deserve our attention:
May 11, 1781: Very faint nebula.

  RA:   187d  9' 42"; 198 25 32, 
  Dec: S 10d 24' 49";  10  0 56.  In Virgo.
  

This is worth examining. The pleasure we have derived from this celestial journey is not yet exhausted.
Let us note immediately that the position of the first of these two indications gives us for 1781:
and for 1860:

  RA = 12h 28m 39s; Dec -10d 24' 49"
  RA = 12h 32m 44s;     -10d 50' 53" 
  

Now, at this position lies the nebula H. I. 43, discovered by William Herschel. It is No. 4594 in Dreyer's New General Catalogue. We can add it to Messier's catalogue, assigning it No. 104. We will study it. Conclusion: Messier's catalog now has 104 entries instead of 103."

[L'Astronomie, vol. 35, pp. 355-359 (September 1921). Description of M104.]
I mentioned that I had noticed in my manuscript of the Messier Catalog, a small note in Messier's handwriting indicating that Méchain discovered, on May 11, 1781, a "very faint nebula" whose position was recorded at

  RA = 187d 9' 42' and Dec -10d 24'49".
  

This position, 12h 28m 39s and -10d 24'49" for 1781, yields, with precession +38.10 and S 19".83, for the year 1920:

  RA = 12h 35m 49' and Dec -11d 10' 45". 
  

This is the nebula listed as No. 4594 in the New General Catalogue by Dreyer = General Catalogue 3132, John Herschel 1376, and William Herschel I.43. I have therefore added it to the Messier Catalogue and listed it under the title Messier 104.
[..]

Helen B. Sawyer [Hogg]: Re-Identification of M104

[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. Flammarion, from pencilled notes in Messier's records, has already suggested the inclusion of NGC 4594 as M104, though this letter published by Méchain was apparently unknown to him."