De Chéseaux's Original List of 21 "Nebulae"

Philippe Loys de Chéseaux compiled an early catalog of deepsky objects. This list of nebulae was written in 1746, and sent to Réaumur, who read it before the French Academy on August 6, 1746, but not otherwise published. Le Gentil (1759) simply mentions these facts without further detail. Thus the list got only published in 1892 by Guillaume Bigourdan within his review article, published in 1892 in the Annales de l'Observatoire de Paris, Observations of 1884, therefore based on investigations in 1884 (Bigourdan 1892).

A translation to English (by HF) follows; corrections, comments etc are of course welcome - please notify me:

My very dear Monsieur Grandfather,

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. The last two are indeed nebulae at simple view, but with a telescope, they are nothing but star clusters; I have observed all two several times with a Gregorian telescope of 2 feet [FL], and in particular, the last but one, which is marked Phi by Bayer, in Scorpius, and which I don't believe is visible from Paris because of its large southern declination. The majority of the others are not nebulae, neither with the eye, nor with the telescope; some even don't appear at sight as simple stars of 4th or 5th magnitude (as, for example, that which is above the top of the head of Hercules); and with a telescope one discovers that in effect it is not one simple star. But I can give you a Catalog of really nebulous stars, be it with a telescope, or be it only with the naked eye, with a number of more than 20: I begin with those which, viewed by telescope, are found to be simple [mostly open] clusters of stars.

1. [M 6, NGC 6405]
Between Scorpius, Ophiuchus, and Sagittarius,there is a very beautiful one, of which the principal stars have this year RA 260d 52' 30" and southern declination 32d 1' 30".
2. [IC 4665?]
Above the shoulder Beta of Ophiuchus, a cluster of stars the two principle stars of which have this year:
RA 264d 46' 50" and Southern Dec. 6d 50' 20"
RA 264d 31' 55" and Southern Dec. 7d 00' 10"
3. [NGC 6633]
Near the tail of Serpens, there is a small star cluster, a bit separated from the great to the west; its RA is at 273d 32' 30" and its southern [actually northern] declination is 6d 19' 20".
4. [M16, NGC 6611]
A star cluster between the constellations of Ophiuchus, Sagittarius, and Antinous [now Scutum], of which RA is 271d 3' 10" and southern declination is 13d 47' 20".
5. [M25, IC 4725]
Another one between the bow and the head of Sagittarius, of which RA is about 274d 17' and southern declination is 19d 11' 30".
6. [NGC 869, h Per] and 7. [NGC 884, Chi Per]
Two star clusters in the fist of the sword of Perseus, already observed by M. Flamsteed.
8. [M 8, NGC 6523]
Another one in the bow of Sagittarius, observed by the same.
9. [NGC 6231+z1,z2 Sco] and 10. [M 7, NGC 6475]
The two last [objects] of the catalog of Messieurs Derham and Maupertuis
11. [M44, NGC 2632]
That in Cancer, commonly called Praesepe, whose position is known.
12. [M35, NGC 2168] and 13. [M71, NGC 6838]
Two others of which I didn't yet determine the positions, one above the northern feet of Gemini, and the other above and very near to Sagitta.
14. [M11, NGC 6705]
Finally, a wonderful cluster of small [faint] stars, near one of the feet of Antinous [now in Scutum], of which RA is 279d 21' 10" and southern Dec is 6d 32' 20"; it is abount 4 1/8 ' in diameter.
These 14 nebulae contain almost more stars visible in the telescope of 25 feet [FL], than half of the sky contains visible to the eye.

Here are now the nebulae properly so called, and which, when observed with much larger telescopes, always appear like white clouds:

15. [M31]
That in Andromeda of which I have talked.
16. [M42]
That in Orion, discovered by Mr. Huygens.
17. [M22]
A third, discovered by Abraham Ihle, between the head and the bow of Sagittarius, for which I found the RA of 275d 14' 10" and the southern declination of 24d 5' 30". It is 5' in diameter, it is round, of reddish color, instead of the yellowish of the Andromeda Nebula and the transparent of that in Orion.
18. [NGC 5139, Omega Cen]
That in Centaurus, discovered by Mr. Halley; it is invisible from Europe.
19. [M 4]
One which is near Antares, which I have found, for this year, at RA 242d 1' 45" and declination 25d 23' 30". It is white, round and smaller than the previous ones; I don't know anyone who noted it previously.
20. [M17]
Finally, another nebula, which has never been observed. It is of a completely different shape than the others: It has perfectly the form of a ray, or of the tail of a comet, of 7' length and 2' broadth; its sides are exactly parallel and rather well terminated, as are its two ends. Its middle is whiter than the borders; I have found its RA for this year as 271d 32' 35" and its southern declination as 16d 15' 6". It has an angle [PA] of 50 deg with the meridian.
21. [M13]
I haven't yet found that in Hercules, which was discovered by M. Halley. I strongly wish that the astronomers at Paris would like to indicate me its place.
The nebulae have been observed with large telescopes and when there was no twilight or moonshine. I will be extremely curious to learn of those which one discovers in the fifth, which has the form of a ray, when observed with refractors of 50 feet [FL] or reflecting telescopes of 7 or 8 feet.

Bigourdan has identified all of De Chéseaux's objects with their NGC numbers with the exception of No.'s 2, 5, 8, 12, and 13. Moreover, he remarks wrong signs for the declinations of No's 2 and 3.


Thanks to Leos Ondra for providing me with a copy of Bigourdan's article!

Hartmut Frommert
Christine Kronberg

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