Sur la Belle Nébuleuse de la ceinture d'Andromède. On the beautiful Nebula in the girdle of Andromeda.

It is at Simon Marius to whom the discovery is given with telescopes, of the beautiful Nebula in 1612, but in a writing of Bouillaud, he has said that it has been remarked more than 600 years before him. (1)

Several astronomers have observed since that time this Nebula of Andromeda, and especially that of the Sward of Orion, discovered by Huygens in 1656, (the most remarkable Nebulae in the sky, which have been observed as the first). For the one and the other, variations have been suspected at the disappearance and the reappearance by a diminution and an augmentation of their light; M. Le Gentil has seen the Nebula of Andromeda, round, then oval; and with a telescope of three feet focal length, he has seen it, on the 7th of January 1758, in the form of two cones or pyramids of light, opposed at their bases, their two tips being elongated between them about 50 minutes of arc, and the common bases of the two pyramids of light od 20 minutes [of arc]. M. Cassini says its figure is a bit close to triangular; (Élemens d'astronomie, page 78).

I say that telescopes more or less long, with magnifications more or less strong, which one employs for observations and for examinations of Nebulae, producing by this different effects, and they look more or less dense and more or less obscure; it is surely the difference in these telescopes of more or less [focal] length which have been employed which have given the variations in the observed shape, described and drew of the two beautiful nebulae. M. Le Gentil as already remarked a preference of a telescope of three feet and one longer which he has employed, and recommends to employ telescopes of the same length to make lesser the effect of having more light, which is suitable for the observation of Nebulae for knowing their extension.

The various drawings which I have seen published of the Orion Nebula, by Huygens, Picard, de Mairan and Le Gentil, have determined me in 1773 to observe and draw it with the aid of an excellent achromatic refractor of 3 1/2 feet [focal] length; it is engraved, Mém. de l'Acad. for the year 1771, pl. VIII.

The astronomers have equally observed changes in that in the girdle of Andromeda, I have devoted myself in 1795, to observe with care with different telescopes for recognizing in the sequence of times if effectively it is susceptible for any variations in its shape. Therefore, I have observed and designed this beautiful Nebula on September 13, 14, 15, 16, 17, 21 and 25, and October 7, 1795, in a very good and clear sky, the Nebula very high over the horizon of its rising.

I have employed three refractors to examine this Nebula, all three achromatic, the first of 3 1/2 feet focal length, at 3 glasses and 40 lignes aperture, with magnification 70, 40, and 36. The second refractor of the same as the first, I don't have made magnified other than 18 times; the third of two glasses and two feet focal length at 25 lignes aperture, its magnification 9 1/2 times. This telescope normally served me for the research of comets, because its little effecct which gives plenty of light and a wide field [of view].

The first of these refractors, with magnification 70, represented the Nebula quite confused; having reduced the magnification to 40, I saw it in almost full extension and its light; the small Nebula which appears below the great and very close, discovered by Le Gentil on October 29, 1749, shows very good, the center very clear, and the other nebulosity becomes insensibly with the azure of the sky; it appears round; its diameter at two minutes of arc. I designed the appearance of the two Nebulae after the magnification of 40 times.

The second refractor employed, I have not made magnify other than 18 times on this object, it made me see the great Nebula in its full extend, the two pyramids of light which are going to get lost in the blue of the sky at a great distance from their common base, like one can see in the drawing which I have designed, the base of these two pyramids where the force of light resides; I didn't notice any appearance of small [faint] stars, if it is not that this light appears to me uneven, like a planing machine (if I'd dare to express it so), extremity of the pyramids fading, widening, and appear to terminate by extremely fine and narrow rays of light. For viewing these effects, one has to care to employ a sensible telescope with equal magnification, when the sky is perfectly good and clear, when the Nebula is at high altitude, near the meridian, with the eyes protected from all the interfering light, and an observer very exercised in observations.

The third refractor of two feet which magnifies 9 1/2 times allowed me to view at less effort the same detail as with the preceding.

On August 10, 1773, examining with care, in a perfectly good and clear sky, the great Nebula, and the small discovered by M. Le Gentil, with an excellent achromatic refractor of 3 1/2 feet focal length, 40 lignes aperture, 3 glasses and a magnification of 68 times, I discovered a small Nebula which had not been yet remarked, well difficult to see, different from the one which M. Le Gentil had discovered; it appears below the great, all three visible in the same field of view of the telescope, and about on the same line of the centers of the three. It is surprising that it had not been seen by M. Le Gentil, nor by me when working on my catalog of Nebula; it has less light than that of M. Le Gentil, and it is to presume that if it has not been seen, this will be the great light of the great Nebula which will have prevented this; for seeing the great nebula must be kept out of the field of view of the telescope; I took its configuration together with the other two; it is reported in my journals, delayed for another time for determining its position, which was done in 1795.

The first of the three refractors cited carried an excellent micrometer of threads and a magnification of 36; the micrometer was employed for the determination of the three nebulae and the surrounding stars, for the extension of the base of the great Nebula I found about 39 minutes of arc (M. Le Gentil found it to be 20 minutes); I found each of the pyramids of 1 degree, both together 2 degrees, i.e. from the extremity of the one to the extremity of the other. It has days when it has more extension; on one it went up to the stars 21 and 22 of the drawing. (M. Le Gentil gave for both 50 minutes [of arc]). It is the star Nu Andromedae, of fourth magnitude, which has been employed for determining the [positions of] the Nebulae and the surrounding stars.

All my determinations were repeated several times, and several drawings were drafted which I approached one by one, they have provided me as well to obtain with enough precision the form and extend of the great Nebula with the two small ones, as well as the stars which I have determined in right ascension and declination for January 1, 1795; they are 23 in number, including Nu Andromedae. The drawing is represented in reverted figure, as seen with the refractor, and it will be easy to recognize the three Nebulae, and the stars with each having its number.

I report in a table which follows, the positions of the stars, their estimated magnitudes with numbers, for being able to recognize each from the drawing which I have created, as well as the two small Nebulae which accompany the great which traverses the drawing from southeast to northwest.

I have neglected to report in the drawing the stars [that are] absolutely telescopic, very difficult to perceive, and almost impossible to determine; those which I have determined are more than sufficient for recognizing over the time, if these Nebulae change in shape or position as several astronomers have suspected.

One feels well that all the measures which I give the three Nebulae are not what approached, seen uncertainty and the difficulty to estimate just the extension of a cluster of light which fades by degradation insensible with the azure of the sky.

Note. The third comet of 1790 was situated, on May 2 in the morning, on the parallel of the great Nebula of Andromeda, with which the comet [position] was compared, and with the star Nu, of fourth magnitude of that constellation; reducing this observation I recognized that I had committed an error in the position of the Nebula {M31], reported in my Memoir of the Nebulae, printed in the Volume of the Acad., 1771. Here is the position rectified from the new observations for August 3, 1764. Read in my Memoir 7d 25' 56" instead of 7d 26' 32"; for the declination 39d 58' 11" instead of 39d 9' 32". For the small discovered by M. Le Gentil [M32], read 7d 24' 55" and 39d 33' 44". MM. [Messieurs] Cassini and Méchain, who have compared the comet with me with the Nebula, found the same error; I have already reported it in the memoir of that comet, Vol. of the acad., 1790, p. 322.

The first column, the numbers which are with the starts in the drawing; the second, their magnitudes; the third, their right ascension and the three Nebulae; the fourth, the differences of right ascension to the center of the [Andromeda] Nebula with the stars; the fifth, the declinations; the sixth, the differences between the Nebula and the stars, and the seventh, if the stars are north or south of the center of the [Andromeda] Nebula. [Diff. E: East of the center, W: At West; N: North, S: South]

 No  Mag  RA 1795   Differ.  Nor. Dec  Diff   North or south of the
          d. m. s.  m. s.    d. m. s.  m. s.  center of the Great Nebula

 22   10   6 54 28  59 19 E  39 18 36  49 51  N
 21   10   6 56 58  56 49 E  39 18 36  49 51  N
 20   11   6 58 13  55 34 E  39 30 30  37 57  N
 19   10   6 58 43  55  4 E  39 33 35  34 52  N
P.N. P.N.  7 18 39  35  8 E  40 32 46  24 19  S, small Nebula. Messier.
 18    7   7 24 43  29  4 E  39  6 24  62  3  N
 17    9   7 27  9  26 37 E  40 35 42  27 15  S
 16    7   7 43 51   9 56 E  39 34  7  34 20  N
 15   10   7 50  2   3 45 E  39 49 36  18 51  N
 14    9   7 52  9   1 38 E  40 33 59  25 32  S
P.N. P.N.  7 53 35   0 12 E  39 44 18  24  9  N, small Nebula. Legentil.
G.N. G.N.  7 53 47   0  0    40  8 27   0  0  Great Nebula, the center.
 13   10   8  1 24   7 37 W  39 53 13  15 14  N
 12   11   8  7 17  13 30 W  39 46 43  21 44  N
 11    9   8 12 54  19  7 W  40 26 34  18  7  S
 10    9   8 17 39  23 52 W  39 33 51  34 36  N
  9    8   8 22  9  28 22 W  39 33 38  34 49  N
  8    9   8 23 54  19  7 W  40 11 10   2 43  S
  7    9   8 37 15  43 28 W  40  3 52   4 35  N
  6    7   8 42 39  48 32 W  39 41 28  26 59  N
  5   10   8 43 39  49 52 W  40 11 18   2 51  S
  4    9   9  1 47  68  0 W  40 10 15   1 48  S
  3    9   9  7 17  73 30 W  40  9 41   1 14  S
  2    8   9 27  9  93 22 W  40  9 47   7 40  N
  1    7   9 30 39  96 52 W  39 57 41  10 46  N
 Nu    4   9 38 24 104 37 W  39 57 41  10 46  N

[The captions in this drawing read, from above: Mém. de l'Inst. Class Math. et Phys. 1.er Semestre, Pag. 213. (Mem. of the Inst. Class Math. and Phys. 1st Semester, pag. 213).
Graticule for 0, 15', 30', 45' 1d deviation from M31's center in RA and Dec.
ANDROMEDA NEBULA.
Directions are marked: N, N-W, S-W, S, S-E, N-E. Marked are the Meridian and the parallel to the Equator.
The stars are marked with the numbers given in the table above. The nebulae are marked as follows: M 31, G.N. (Grand Nébuleuse, Great Nebula), Simon Marius 1612 and 600 years before, beautiful at sight (with the unaided eye). M 32, P.N. (Petite Nébuleuse, Small Nebula), Le Gentil 1749, plus belle (more beautiful). M 110, P.N. (Petite Nébuleuse, Small Nebula), Messier 1773, plus foible (fainter).
Magnitudes of the Stars [symbols given, mag 4 to 11]; Ladder of Minutes of Arc [scale given].
Engraved by E. Collin, after a drawing by M. Messier. The Circle is the background of the Sky, which cuts the field (of view) of the refractor.]

Reference:

• Charles Messier, 1807. Observations et dessin de la grande et belle nébuleuse de la ceinture d'Andromède, la première qui fut découverte, et de deux petites nébuleuses, l'une au-dessus de la grande et le seconde au-dessous, vues dans une lunette qui renverse, comme le dessin. (Observations and drawing of the great and beautiful nebula in the girdle of Andromeda, the first which was discovered, and the two small nebulae, the one above the great and the second below it, viewed with a reversing telescope, with the drawing.) Rec. Inst., Vol. 8 (Mém. de l'Institut, Premier Semestre de 1807), 1807, pp. 206-213 + Plate [Bibcode: 1807RecIn...8..206M].

• Charles Messier's publications

Initial version: February 28, 2005
Last Modification: November 20, 2019