Lacaille and his catalog of clusters and nebulae (original) (raw)

Lacaille's "Catalog of Nebulae of the Southern Sky"

Nicholas Louis de la Caille (1713-1762) compiled a catalog of 3 times 14 nebulous objects. Of these, 8 or 9 are classified as non-existent in the older literature, although Vehrenberg gives a NGC number for one of them. New research, independently done by Glen Cozens of Australia, Ronald Stoyan of Germany, and the present author [hf], has only recently led to their identification. On the other hand, the old identification of Lacaille's object I.11 with M69, by Charles Messier, could be eliminated with great probability. Thus, probably 7 of these catalog entries are asterisms or stars and no "real" deepsky objects.

Lacaille classified his objects in 3 categories:

Lac I:

Nebulae

Lac II:

Nebulous Star Clusters

Lac III:

Nebulous Stars

However, though this classification may have been suggestive with Lacaille's very small instruments, 0.5 inch refractors, according to R.H. Allen (1899) and Evans (1992), it does not correspond to actual properties of the objects (perhaps besides that all existing category II objects are actually open clusters, with or without nebulosity).

There's a number of remarkable objects and original discoveries in Lacaille's list; perhaps the most remarkable one is M83, the first galaxy beyond the Local Group to be discovered.

This catalog was compiled during his 2-year journey to the Cape of Good Hope in 1751-52, and is given below (widely based on the article on Lacaille inHans Vehrenberg's book; an ascii version is also available). We also have an online version of Lacaille's original catalog, as reprinted in 1781 in an appendix to Messier's Catalog in the Connoissance des Temps for 1784, and a translation ofLacaille's original catalog of 1755.

Lacaille D NGC Name Type RA (2000) Dec Con mag Dim/'

Lac I.1 * 104 47 Tuc Gl 00:24.1 -72:05 Tuc 3.95 30.9 Lac I.2 * 2070 30 Dor DN 05:38.7 -69:06 Dor 40x25 Lac I.3 * 2477 OCl 07:52.3 -38:33 Pup 5.8 27 Lac I.4 * 4833 Gl 12:59.6 -70:53 Mus 6.91 13.5 Lac I.5 5139 Omega Cen Gl 13:26.8 -47:29 Cen 3.68 36.3 Lac I.6 * 5236 M83 S G 13:37.0 -29:52 Hya 7.6: 11x10 Lac I.7 * 5281 OCl 13:46.6 -62:54 Cen 5.9 5 Lac I.8 * 6124 OCl 16:25.6 -40:40 Sco 5.8: 29 Lac I.9 6121 M4 Gl 16:23.6 -26:32 Sco 5.9 26.3 Lac I.10 * 6242 OCl 16:55.6 -39:30 Sco 6.4 9 Lac I.11 * 6634 3st 18:30.0 -33:29 Sgr 7.3 4 (3 stars, GC 5076; probably not M69) Lac I.12 6656 M22 Gl 18:36.4 -29:54 Sgr 6.5 24.0 Lac I.13 6777 - 2st 19:26.8 -71:30 Pav (2 stars 8.0 and 8.3 mag; GC 4484) Lac I.14 * 6809 M55 Gl 19:40.0 -30:58 Sgr 7.0 19.0

Lac II.1 - Ast 04:03.7 -44:27 Hor (asterism of 12 stars mag 7.5..9.5) Lac II.2 * - Cr 140? OCl? 07:26.3 -34:08 Pup OCl Cr 140? (asterism of 8 stars mag 5.9..8.9 ?) Lac II.3 * 2516 OCl 07:58.3 -60:52 Car 3.8 30 Lac II.4 * 2546 OCl 08:12.4 -37:38 Pup 6.3 41 Lac II.5 I2391 o Vel OCl 08:40.2 -53:04 Vel 2.5 50 Lac II.6 * - Tr 10? OCl? 08:46.6 -42:34 Vel 4.6? 15? OCl Trumpler 10 ? Lac II.7 * 3228 OCl 10:21.8 -51:43 Vel 6.0 18 Lac II.8 * 3293 DNCl 10:35.8 -58:14 Car 4.7 6 Lac II.9 * I2602 Theta Car OCl 10:43.2 -64:24 Car 1.9 50 Lac II.10 * 3532 OCl 11:06.4 -58:40 Car 3.0 55 Lac II.11 - Ast 11:23.0 -58:19 Cen (line of 8 stars mag 6.6..8.5) Lac II.12 * 4755 Kappa Cru OCl 12:53.6 -60:20 Cru 4.2 10 Lac II.13 6231 OCl 16:54.0 -41:48 Sco 2.6 15 Lac II.14 6475 M7 OCl 17:53.9 -34:49 Sco 3.5 80.0

Lac III.1 - st 05:03.3 -49:29 Pic (single star mag 7.1 or 7.2, HD 32806 = SAO 217150) Lac III.2 * 2547 OCl 08:10.7 -49:16 Vel 4.7 20 Lac III.3 * I2395? vdB-Ha47? OCl? 08:42.2 -48:04 Vel 13? OCl vdB-Ha 47 ? Lac III.4 * I2488 OCl 09:27.6 -56:59 Vel 7.4p 15 Lac III.5 * - Cr 228? OCl? 10.43.0 -60:01 Car 4.4 5 Cr 228 in NGC 3372 Lac III.6 * 3372 Eta Car DN 10:43.8 -59:52 Car 120x120 Lac III.7 * 3766 OCl 11:36.1 -61:37 Cen 5.3 12 Lac III.8 * 5662 OCl 14:35.2 -56:33 Cen 5.5 12 Lac III.9 - Ast 15:22.6 -59:12 Cir (asterism of 3 stars mag 8.1, 7.6, 7.9) Lac III.10 * 6025 OCl 16:03.7 -60:30 TrA 5.1 12 Lac III.11 * 6397 Gl 17:40.7 -53:40 Ara 5.73 25.7 Lac III.12 6405 M6 OCl 17:40.1 -32:13 Sco 4.5 15.0 Lac III.13 6523 M8 DN 18:03.8 -24:23 Sgr 5.0 60x35 Lac III.14 - Ast 21:31.4 -58:35 Ind (asterism of 3 stars mag 8.4, 8.2, 9.1)

Key

Lacaille:

Lacaille number

D:

An asterix ("*") marks the original and true discoveries of Lacaille (otherwise, it was either discovered prior by others, or is not a real deepsky object [but an asterism or star])

NGC:

NGC or IC number

Name:

Common Name, Flamsteed, or Messier number

Type:

DN: Diffuse Nebula; DNCl: Nebula with Cluster; OCl: Open Cluster; Gl: Globular Cluster; S G: Spiral Galaxy; Ast: Asterism; 2st: Two stars; st: [single] Star

RA, Dec:

Position 2000.0

Con:

Constellation

mag:

Apparent visual magnitude (where av)

Dim/':

Apparent (angular) dimension (in arc minutes)

In each category, Lacaille's objects are apparently sorted by right ascension. Unfortunately, we have no source for the discovery dates (as we have for Messier's observations), so that we cannot give a sequence.

The Lacaille catalog has been originally published under the title "Sur les étoiles nébuleuses du ciel Austral" (On the Nebulous Stars of the Southern Sky) in the Memoirs of the Royal Academy of Sciences in Paris, 1755, and reprinted together with Messier's catalog in the "Connoissance des Temps", both with the second version in 1780 (for 1783) and the final version in the "Connoissance des Temps" for 1784 (published 1781).

In this version of the Lacaille catalog, we have now tentatively (with "?") added the new identifications of the formerly missing Lacaille objects mentioned above; this concernsLacaille III.3 (which Vehrenberg has as unidentified open cluster, but the present author and independently Glen Cozens and Ronald Stoyan identified vdB-Ha 47),Lacaille II.6 (which Glen Cozens and independently Ronald Stoyan identifies with considerable open cluster Trumpler 10), as well as Lacaille II.2 (Collinder 140) and Lacaille III.5 (Collinder 228), both identified by Ronald Stoyan. Eventually, Glen Cozens has found that Messier's identification of Lac I.11 with M69 has been erroneous, and identified it with an asterism of 3 stars.

Including these objects, a total of 10 objects (I.11, I.13, II.1, II.2, II.6, II.11, III.1, III.3, III.9 and III.14) were not commonly recognized as known deepsky objects, and in this sense "missing". We have a discussion of the missing Lacaille objects online; thanks to Glen Cozens and Ronald Stoyan for contributing their research!

In appendix to his 1755 catalog, Lacaille also mentions and gives a brief description of the Coalsack Dark Nebula.

Other important astronomical work accomplished by Lacaille includes a catalog of southern stars, and the invention of a number of southern constellations, many of which are still in use today.

Links

Hartmut Frommert
Christine Kronberg
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Last Modification: June 15, 2016