Lacaille and his catalog of clusters and nebulae

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 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 1781 in an appendix to Messier's Catalog in the Connoissance des Temps for 1784, and a translation of Lacaille'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 concerns Lacaille 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

Lacaille's original catalog, as reprinted in 1981 in an appendix to Messier's Catalog in the Connoissance des Temps for 1784.
Lacaille's Original Object Positions
Missing Lacaille Objects
History of the Identification of Lacaille's Objects
Short biography of Nicholas Louis de Lacaille
Other catalogs similar to those of Lacaille and Messier, suitable as amateur checklists, but of less historical importance
History of the Discovery of the Deepsky Objects

References

Nicholas Louis de Lacaille. Sur les étoiles nébuleuses du Ciel Austral [On the nebulous stars of the Southern Sky]. Memoirs of the Royal Academy for 1755 (Paris), pp. 194-199.
Charles Messier, 1781. Nébuleuses du ciel austral. Observées par M. l'abbé de la Caille, au cap de Bonne-espérance [Nebulae of the southern sky. Observed by M. l'Abbé de la Caille, at the Cape of Good Hope], pp. 270-272. (Reprint of the 1755 catalog as appendix to the Messier catalog, with remarks on the identification of the Messier objects in Lacailles catalog). Also note the previous reprints of 1771 (Memoirs of the Academy) and 1780 (pp. 252-254 in the Connoissance des Temps for 1783) and the later reprint of 1784 in the Connoissance des Temps for 1787.
Richard Hickley Allen. Star Names, Their Lore and Meaning. Dover Publication, New York, 1963. Corrected republication of Star-Names and Their Meaning, published by G.E. Stechert in 1899.
David S. Evans, 1992. Lacaille: Astronomer, Traveler. Pachart History of Astronomy Series, Vol. 9, Series Editor: A.G. Pacholczyk. Pachart Publishing House, Tucson, Arizona.
Owen Gingerich, 1960. Abbe Lacaille's List of Clusters and Nebulae. Sky and Telescope, Vol. 19, No. 2 (February 1960), pp. 207-208 [ADS: 1960S&T....19..207G].
Hans Vehrenberg, 1965/1978. Atlas of Deep Sky Splendors. Vehrenberg and Sky Publishing. 1st ed 1965, 3rd ed. 1978. Contains a chapter on "La Caille and his catalog of southern objects."

Hartmut Frommert
Christine Kronberg
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Last Modification: June 15, 2016