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[M 31]

Messier 31

Observations and Descriptions

Known to Al-Sufi about AD 905 and depicted AD 964.
Reported on a Dutch starmap of 1500.
Independently found and first observed with a telescope by Simon Marius on December 15, 1612.
Independently rediscovered by Hodierna before 1654.

Messier: M31.
August 3, 1764. 31. 0h 29m 46s (7d 26' 32") +39d 09' 32"
The beautiful nebula of the belt of Andromeda, shaped like a spindle; M. Messier has investigated it with different instruments, & he didn't recognise a star: it resembles two cones or pyramides of light, opposed at their bases, the axes of which are in direction NW-SE; the two points of light or the apices are about 40 arc minutes apart; the common base of the pyramids is about 15'. This nebula was discovered by Simon Marius, & consequently observed by different astronomers. M. le Gentil has given a drawing in the Memoirs of the Academy for 1759, page 453. It is reported on the English Atlas. (diam. 40')

(Flammarion reports that Messier added a note in his personal copy of the catalog by hand: `I have employed different instruments, especially an excellent Gregorian telescope of 30 feet FL, the large mirror 6 inches in diameter, magnification 104x. The center of this nebula appears fairly clear in this instrument without any stars appearing. The light gradually diminishes until it becomes extinguished. The former measurements were made with a Newtonian telescope of 4.5 feet FL, provided with a silk thread micrometer. Diameter 40'. August 3, 1764.')

[Mem. Acad. for 1771, p. 446-447 (first Messier catalog)]
The sky has been very good in the night of August 3 to 4, 1764; & the constellation Andromeda was near the Meridian, I have examined with attention the beautiful nebula in the girdle of Andromeda, which was discovered in 1612 by Simaon Marius, & which has been observed since with great care by different astronomers, & at last by M. le Gentil who has given a very ample & detailed description in the volume of the Momoirs of the Academy for 1759, page 453, with a drawing of its appearance. I will not report here what I have written in my [observing] Journal: I have employed different instruments for examining that nebula, & above all an excellent Gregorian telescope of 30 pouces focal length, the large mirror having 6 pouces in diameter, & magnifying 104 times these objects: the middle of that nebula appeared rather bright with this instrument, without any appearance of stars; the light went diminishing up to extinguishing; it resembles two cones or pyramides of light, opposed at their bases, of which the axis was in the direction form North-West to South-East; the two points of light or the two summits are about 40 minutes of arc apart; I say about, because of the difficulty to recognize these two extreminties. The common base of the two pyramides is 15 minutes [of arc long]: these measures have been made with a Newtonian telescope of 4 feet & a half focal length, equipped with a micrometer of silk wires. With the same instrument I have compared the middle of the summits of the two cones of light with the star Gamma Andromedae of fourth magnitude which is very near to it, & little distant from its parallel. From these observations, I have concluded the right ascension of the middle of this nebula as 7d 26' 32", & its declination as 39d 9' 32" north. Since fifteen years during which I viewed & observed this nebula, I have not noticed any change in its appearances; having always perceived it in the same shape.
[p. 457] 1764.Aug. 3. RA: 7.26.32, Dec: 39. 9.32.B, Diam: 0.40. The beautiful nebula in the girdle of Andromeda.

Al Sufi
[First depicted it in his "Book of Fixed Stars" of 964 A.D.]
A Little Cloud.

[Observation of December 15, 1612, from his Mundus Jovialis]
Of these observation the first is, that since December 15, 1612, I have discovered & observed a star or a fixed star, as I could not find elsewhere in all the sky. It is situated near the third & northern star in the girdle of Andromeda. Without instrument there can be seen something like a nebula; but with the telescope no stars can be seen, as in the nebula in Cancer [Praesepe, M44] & other nebulous stars, but only glimmering rays, which are the brighter the closer they are to the center. In the center is a faint & pale glow which occupies a diameter of about a quarter of a degree. A similar glow occurs, if the flame of a candle is seen through transparent horn. The nebula appears not dissimilar to the comet, which Tycho Brahe has observed in the year 1586.
In September of last year [1613], the highly erudite gentleman M. Lucas Brunnius, mathematician at His Highness the Elector of Saxony was staying with me. Between our mathematical colloquia, with the sky offering great serenity, I also showed him this strange star; he observed it with the greatest admiration. If, however, this stars is a new one, I cannot say with certainty; others may determine & judge this. I'm surprised about the most sharpviewed Tycho, who has determined for a fixed star lying little more north in the girdle of Andromeda, with his instruments, longitude & latitude, but left untouched this nebula, despite it is very close to it.

Hodierna: Ha III.3.
A very admirable [nebula] never seen (to my knowledge) by anyone. It is the unresolvable star over the right tigh of Andromeda. No multitude of close stars can be distinguished in it but [it looks similar] to a comet.

Hevelius: No. 32.
[Nebulosa (nebulous star)] In Andromeda's Girdle

[in Phil. Trans. XXII, p. 383 (1667)]
.. As to the other [variable star] in the Girdle of Andromeda, seen about the beginning of An. 1665; he relates, that, when in the end of 1664. the World beheld the then appearing Comet,, Astronomers observed also that new Phenomenon, which was called by them Nebulosa in Cingulo Andromeda. Concerning which, he notes, that the same had been already seen many years before by Simon Marius, vid. An. 1612. when with a Telescope he search'd for the Satellits of Jupiter, and observed their motions; alledging for proof hereof, the said Authors own words, out of his own Book, De Mundo Joviali, publisht An. 1614. And farther shews, that it hath formerly appear'd (about 150. years ago) and been taken notice off by an expert, though Anonymous, Astronomer; whose words he cites out of the Manuscript, brought out of Holland by the Excellent Jacobus Augustus Thuanus, returning from his Embassy to Paris; wherein also was marked the Figure of that Phaenomenon, represented in print by our Author: who from all this collects, that, whereas this Star hath been seen formerly, and that 150. years since, but yet neither observed by Hipparchus, nor any other of the Antients, that we can find; nor also in the former Age by Tycho Brahe, nor in our Age, by Bayerus; and appear'd also in the Month of November last (wherein he wrote this Tract) much lessened and obscure, after it had, two years ago, shone very bright; that therefore it must needs appear and dis-appear by turns, like those in the Necks of the Whale [Mira] and Swan [P Cygni].

Flamsteed: Flamsteed 58.

Halley (1716): No. 2, Nebula in the Girdle of Andromeda.
[in Phil. Trans. XXIX, 390 (1716)] About the Year 1661 another of this sort was discovered (if I mistake not) by Bullialdus, in Cingulo Andromedae [in the Girdle of Andromeda]. This is neither Tycho nor Bayer, having been omitted, as are many others because of its smallness: But it is inserted into the Catalogue of Hevelius, who has improperly call'd it Nebulosa instead of Nebula; it has no sign of a Star in it, but appears like a pale Cloud, and seems to emit a radiant Beam into the North East, as that in Orion does in the South East. It precedes in Right Ascension the Northern in the Girdle, or Nu Bayero [Nu And, according to Bayer], about a Degree and three Quarters, and has Longitude at this time [Aries] 24 deg 00' with Lat. North 33 deg 1/3.

Derham: No. 1 [from Hevelius]
[Nebulosa] In Andromeda's Girdle.
To conclude these Remarks, it may be of use to take Notice, that in Hevelius's Nebulosae, some seem to be more large, and remarkable than others; but whether they are really so, or no, I confess I have not had Opportunity to see, except that in Andromeda's Girdle, which is as considerable as any I have seen. ..

De Chéseaux: De Ch. No. 15.
That in Andromeda of which I have talked.
[In text:] Mr. Derham, in the Philosophical Transactions, and after him Mr. de Maupertuis, in the Memoires of the Academy, have given a Catalog of nebulae, extracted from the great Catalog of fixed stars of Hevelius, and that of the southern Stars by Mr. Halley. I have observed most of these nebulae, and I haven't found any but the first, which is that in Andromeda, which really deserves this name.

Bode: Bode 3.
Nebula visible to the naked eye, 15' diameter.

Bode (1782):
[From: Vorstellung der Gestirne auf XXXIV Kupfertafeln (Introduction to the Stars on 34 Copper Plates), 1782. Here Plate XXX, p. 38-39]
Fig. 8. The remarkable nebula visible to the naked eye in the belt of Andromeda. It has 40 [arc] minutes in its greatest length, according to Mr. Messier; [it] appears like two cones or pyramids, the bases of which are posed upon each other and are 15 [arc] minutes in diameter. Otherwise, no stars can be recognized within it even with the best telescopes. The small neighboring stars are depicted according to le Gentil, who also has found, south of the previous, a small faint nebula of 2 minutes diameter, which was also seen by Mr. Messier [M32].

William Herschel
[First observed M31 on August 6, 1780]

[1785. PT LXXV=75, p. 213-266; here p. 262]
The ninth [very compound Nebula, or Milky-Way] is that in the girdle of Andromeda, which is undoubtedly the nearest of all the great nebulae; its extent is above a degree and a half in length and, in even one of the narrowest places, not less than 16' in breadth. The brightest part of it approaches to the resolvable nebulosity, and begins to shew a faint red colour; which, from many observations on the colour of and magnitude of nebulae, I believe to be an indication that its distance in this coloured part does not exceed 2000 times the distance of Sirius. There is a very considerable, broad, pretty faint, small nebula [M110] near it; my Sister [Caroline] discovered it August 27, 1783, with a Newtonian 2-feet sweeper. It shews the same faint colour with the great one, and is, no doubt, in the neighborhood of it. It is not the 32d of the Connoissance des Temps [M32]; which is a pretty large round nebula, much condensed in the middle, and south following the great one; but this is about two-thirds of a degree north preceding it, in a line parallel to Beta and Nu Andromedae.

[1814. PT 1814 (vol. 104), p. 248-284; here p. 260]
8. Of objects of ambiguous construction
.. But when an object is of such a construction, or at such a distance from us, that the highest power of penetration, which hitherto has been applied to it, leaves it undetermined whether it belongs to the class of nebulae or of stars, it may be called ambiguous. As there is, however, a considerable difference in the ambiguity of such objects, I have arranged 71 of them into the following four collections. [First collection contains M31]
The first contains seven objects that may be supposed to consist of stars, but where the observations hitherto made, of either their appearance or form, leave it undecided into which class they should be placed.
Connoiss. 31 [M31] is "A large nucleus with very extensive nebulous branches, but the nucleus is very gradually joined to them. The stars which are scattered over it appear to be behind it, and seem to lose part of their lustre in the passage of their light through the nebulosity; there are not more of them scattered over the immediate neighborhood. I examined it in the meridian with a mirror of 24 inches in diameter, and saw it in high perfection; but its nature remains mysterious. Its light, instead of appearing resolvable with this aperture, seemed to be more milky."
The objects in this collection must at present remain ambiguous.

On NGC 206 (H V.36):

[1811: PT Vol. 1811, p. 226-336; here p. 280]
4. Of detached Nebulosities.
The nebulosities of the preceding article [on Nebulosities joined to Nebulae] are not restricted to an extensive diffusion; we meet with htem equally in detached collection; I shall only mention the following 6 [including H V.36 = NGC 206].

John Herschel (1833): h 50.
h 50 = M 31.
Sweep 180 (September 18, 1828)
RA 0h 33m 26.3s, NPD 49d 39' 40" (1830.0) [Right Ascension and North Polar Distance]
The great nebula in Andromeda.

Smyth: XXIV [24]. M31.
XXIV. 31 M. Andromedae.
AR 0h 34m 5s, Dec N 40d 23'.6
Mean Epoch of Observation: 1833.70 [Sep 1833]
[with drawing of M31 and M32]
sf [south following, SE] edge of the general mass, and of a milky irresolvable nebulosity; but though described "in cingulo Andromedae," it is between the robes and the left arm of the Lady, and certainly below its girdle. There are numerous telescopic stars around; and three minute ones are involved in the glow, but which can have no connection with it, and are doubtless between our system and the nebulosity. The axis of direction trends sp and nf [south preceding and north following, SW to NE]; and it may be caught by a good eye, on a very fine night, by running a fancied line from Alamak to Mirak, and from thence carrying a rectangular glance to a distance of about 6 1/2 deg. It can also be struck upon by a ray from Gamma in the mouth of Cetus, over Sherathan in the head of Aries, through Mirak, or Beta Andromedae, to 6 1/2 deg beyond.
This is the oldest known nebula; for though it attracted but little notice till the seventeenth century, it was seen, at least, as far back as 905 A.D. Simon Marius re-discovered it, -- if such a term can be applied to an object seen with the naked eye: in his rare work -- De Mundo Jovialis -- that astronomer acquaints us, that he first examined it with a telescope on the 15th Dec. 1612; he was astonished at the singularity of the phenomenon, but expressly says, that he leaves it to others to judge whether it was a new discovery or not. It was therefore by an oversight, that Halley ascribes the discovery, in 1661, to Bullialdus (Ismaël Boulliaud); who himself mentions its being known as Nebulosa in cingulo Andromedae, and that it had been noticed 150 years before, by an expert though anonymous astronomer. The tenuity of its boundary offering no definition for exact comparison, has made the several attempts to figure it so conflicting as to mislead. Marius describes it as resembling the diluted light of the flame of a candle seen through horn, -- Halley mentions that it emits a radiant beam, -- Cassini calls it à peu-près triangulaire, -- Le Gentil considered it round for some years, then oval, but always of an uniform light in all its parts, -- while Messier represents it as resembling two cones, or pyramids of light, opposed by their bases. From such statements, Boulliaud and Kircher thought this wonderful object appeared and disappeared, like Mira; and Le Gentil had no doubt of its undergoing changes in form. But probably this discordance is a consequence of the means employed. Le Gentil, by his paper of 1749, seems to have used telescopes of various sizes, in order to see it very clearly -- "non seulement pour servir à la reconnoître, mais encore pour voir si dans la suite elle ne seroit point sujette à variation, soit dans la figure, soit dans la position;" yet fifteen years afterwards Messier differs from him, by assigning a greater brilliance to the centre than to the edges, which latter accords better with my views of it, than do our apparent mean places. It is, however, remarkable that Messier examined this giant nebula with a 4 1/2 foot Newtonian, and then turned the instrument upon Gamma Andromedae -- "qui en étoit fort près" -- to compare its light with that of the star, on a beautiful night of August, 1764; but he makes no mention of the duplicity, or contrasted colours, of that lovely star.

The companion [M32] was discovered in November, 1749, by Le Gentil, and was described by him as being about an eighth of the size of the principal one; he adds, "elle m'a paru exactement de la même densité que l'ancienne." The light is certainly more feeble than here assigned. Messier - whose No. 32 it is - observed it closely in 1764, and remarked, that no change had taken place since the time of its being first recorded. In form it is nearly circular. The powerful telescope of Lord Rosse (*) has been applied to this, after finding that no actual re-solution in the large nebulae could be seen, though its edge had stellar symptoms; and it proved to be clearly resolvable into stars - the which directly interferes with Le Gentil's remark.

(*) This telescope is a reflector of three feet in diameter, of performance hitherto unequalled. It was executed by the Earl of Rosse, under a rare union of skill, assiduity, perseverance, and muniference. The years of application required to accomplish this, have not worn his Lordship's zeal and spirit; like a giant refreshed, he has returned to his task, and is now occupied upon a metallic disc of no less than six feet in diameter. Should the figure of this prove as perfect as the present one, we may soon over-lap what many absurdly look upon as the boundaries of the creation.

John Herschel, General Catalogue: GC 116.
GC 116 = h 50 = M 31.
RA 0h 35m 3.9s, NPD 49d 54' 45.7" (1860.0) [Right Ascension and North Polar Distance]
!!! eeB; eL; vmE; (Androm. Gt. Neb.) Bifid (Bond). 13 observations by William and John Herschel.
Magnificient! Excessively extremely bright; extremely large; very much extended; (Andromeda Great Nebula).
Remark: Figure in Bond's Memoirs in vol. viii N.S. of the Transactions of the American Academy of Arts and Sciences, opp. p. 86.

[from Phil. Trans. Vol. 154 (1864), p. 437-444, here p. 441]
[No. [GC] 116. 50 h. 31 M. R.A. 0h 35m 3s.9. NPD 49d 29' 45".7.] The brightest part of the great nebula in Andromeda was brought upon the slit.
The spectrum could be traced from about [Fraunhofer lines] D to F. The light appeared to cease very abruptly in the orange; this may be due to the smaller luminosity of this part of the spectrum. No indication of bright lines.

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 224
NGC 224 = GC 116 = h 50; Sûfi, M 31.
RA 0h 35m 7s, NPD 49d 29.8' (1860.0) [Right Ascension and North Polar Distance]
!!! eeB, eL, vm E (Andromeda); = M31
Magnificient, excessively extremely bright, extremely large, very much extended (Andromeda nebula).
Remark: Figure (together with NGC 205 = M110, NGC 206 and NGC 221 = M32) in Bond [W.C. and G.P. Bond, Transactions of American Academy of Arts and Sciences, N.S. vol. iii], opp. p. 86; Bondoni [Mem. d. Oss. Col. Rom. 1840-1]; H.C. [Winlock and Trouvelot, Annals of Harvard College Observatory, vol. viii], plate XXXIII.

[Photographs of Nebulae and Clusters, Made with the Crossley Reflector, by James Edward Keeler, Director of the Lick Observatory, 1898-1900. Publications of the Lick Observatory, Vol. VIII, 1908]
[Plate 1. The Great Nebula in Andromeda]
[p. 30] NGC 224, RA=0:37:17, Dec=+40:43.4 (1900.0), Great Nebula in Andromeda.
[p. 45] No. 1, NGC 224, 1899 Sep 7, exp. 3h 00m, Enl. 2.0, Top W, Great Nebula in Andromeda.

[Descriptions of 762 Nebulae and Clusters photographed with the Crossley Reflector. Publ. Lick Obs., No. 13, Part I, p. 9-42]
NGC 224, RA= 0:37 , Dec=+40:43. The Great Nebula in Andromeda, [Publ. Lick Obs.] Vol. VIII, Plate 1. This wonderful object, the largest of the spiral nebulae, is too well known to need description. Exposures of 1m to 3m on S23 show an almost stellar nucleus, with traces of spiral structure in the surrounding nebular matter. See Abs. Eff.
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