Lacaille and his catalog of clusters and nebulae

Lacaille’s “”

Lacaille (Abbe Nicholas Louis de la Caille, 1713–1762)

compiled a catalog of 3 times 14 nebulous objects, of which 8 are

non-existent though (although Vehrenberg gives a NGC number for one of them).

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, 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 in

Hans Vehrenberg’s book;

an ascii version is also available).

We also have an online version of

Lacaille’s original catalog, as reprinted in 1981

in an appendix to Messier’s Catalog in the

Connaissance des Temps for 1784.


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 * 6637 M69 Gl 18:34.4 -32:21 Sgr 7.7 7.1 Lac I.12 6656 M22 Gl 18:36.4 -29:54 Sgr 6.5 24.0 Lac I.13 6777 - - 19:26.8 -71:30 Pav (2 stars 8..9 mag nearby; GC 4484) Lac I.14 * 6809 M55 Gl 19:40.0 -30:58 Sgr 7.0 19.0
Lac II.1 - - 04:03.7 -44:27 Lac II.2 - - 07:26.3 -34:08 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 - - 08:46.6 -42:34 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 Cru 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 - - 11:23.0 -58:19 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 - - 05:03.3 -49:29 Lac III.2 * 2547 OCl 08:10.7 -49:16 Vel 4.7 20 Lac III.3 * OCl? 08:42.2 -48:04 Cluster ? Non-existent ? Lac III.4 *I2488 OCl 09:27.6 -56:59 Vel 7.4p 15 Lac III.5 * 3372 Eta Car DN 10:43.8 -59:52 Car 120x120 Lac III.6 * 3372 Eta Car DN 10:43.8 -59:52 Car 120x120 (= Lac III.5) 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 - - 15:22.6 -59:12 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 - - 21:31.4 -58:35

Key

Lacaille:

Lacaille number

D:

An asterix (“*”) marks the original and true discoveries of Lacaille

(otherwise, it was either discovered prior by others, or doesn’t exist)

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

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 etoiles nebuleuses 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

Connaissance des Temps“, both with the second version in 1780 (for 1783)

and the final version in the “Connaissance des Temps” for 1784

(published 1781).

In this version of the Lacaille catalog, there’s still one problem with

Lacaille III.3. Vehrenberg states it is an open cluster, but the Sky Catalog

2000.0 has no considerable open cluster near Lacaille’s position.

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.


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