Lacaille III.3
In his catalog, Abbe Lacaille
describes in the third place in his third part
(“Star Accompanied by Nebulosity”) a
“Star of 6th magnitude, connected to another more southern one by a
nebulous trace.”
While in the 3rd edition of his Atlas of Deep Sky Splendors,
Hans Vehrenberg classifies this object as (open) cluster, other catalogs
contain no hint on this Lacaille object, and in the 4th edition, also
Vehrenberg (or his succeeding editor) marks it as non-existent.
Getting curious, the present author has investigated the field around this
catalog entry, which has the coordinates RA=08:42.2, Dec=-48:04 (precessed
to epoch J2000.0) and is situated in the constellation Vela.
The Sky Catalogue 2000.0 gives positions for the following clusters near
Lacaille’s position:
Object RA Dec
[Lac III.3] 08:42.2 -48:04 IC 2395 08:41.1 -48:12 NGC 2660 08:42.2 -47:09 vdB-Ha 47 08:42.6 -48:07 NGC 2670 08:45.5 -48:47
Cluster van den Bergh-Hagen 47 is closest to Lacaille’s position, but
missing e.g. in the Simbad online database.
The view of a Deep Sky Survey image of the Lacaille place revealed a
surprise: Well near the center of this image is a small cluster (probably
vdB-Ha 47), as well as the two stars described by Lacaille. It is, however,
uncertain and not probable that there is a physical connection between the
stars and the cluster, so that the “object” described by Lacaille is
probably an uninteresting asterism, and the nebulous trace may or may not
have some relation to vdB-Ha 47.
Moreover, a check of the position of IC 2395 indicates that this cluster
can hardly be identified in the Digital Sky Survey.
Digital Sky Survey images of the surroundings of Lacaille III.3:
Thanks to Arnaldo Arnal for interesting
discussion of this thread.
Last Modification: 14 Feb 1998, 17:30 MET