A Compilation Of SMC Star Clusters
By Max Gardner AM
As a follow-up to my reworking of the Shapley-Lindsay (SL) catalogue of LMC star clusters, a similar plan of attack has been used for the star clusters of the SMC. The number of catalogued objects here is only a fraction of that in the LMC, so it was fairly straightforward to work through all 220 clusters identified by Hodge & Wright (1977) in their atlas of the SMC.
Lindsay Catalogue of SMC clusters.
Four catalogues of SMC clusters were used by Hodge and Wright in compiling their SMC atlas, with Eric Lindsay's 1958 catalogue being the longest, with 116 entries. I have given Lindsay's compilation priority status, and kept his clusters in correct numerical order, even though the precise J2000 positions are not always strictly in order of increasing RA. Entries from other catalogues (K, WG and HW) are inserted in the most appropriate positions, according to RA. Compared to the LMC, identification problems were rare, and the Hodge-Wright atlas was found to be very reliable, displaying the positions of clusters with commendable accuracy. Nevertheless, Lindsay's published catalogue was consulted to be sure no vital information was missed. Curiously, while the Lindsay catalogue gives diameters in arcmin for each cluster, the values given are generally far too large, up to 79 arcmin. It is clear that some other scale is meant, perhaps an absolute diameter in parsecs? The BSDL diameter data has been inserted instead.
Douglas Welch (1991) published a list of astrometric positions for 203 SMC clusters, omitting 17 objects which could not be measured for various reasons. After extensive checking against other catalogues his data have been accepted in their entirety.
All clusters have been searched for in the GSC, via Guide7. Some clusters not in the GSC were found in the USNO-A2.0, while a few had to be estimated by reference to nearby USNO-A2.0 stars.
Machine-Readable Catalogs Used
General identifications; diameters.
1."Revised and extended catalog of Magellanic system clust, associations
and emission nebulae", II. Bica, E.L.D., Schmitt, H.R., Dutra, C.M.
and Oliveira, H.L. Astron. J. 117, 238-246 (1999). [BSDL]
See also http://www.if.ufrgs.br/~dutra/catpage.html
2. The Guide Star Catalog, v1.1, Space Telescope Science Institute
3. USNO-A2.0 Catalog, Monet, D., Bird, A., Canzian, B. et al 1998,
US Naval Observatory, Washington DC. [USNO-A2.0]
See also http://www.usno.navy.mil/pmm
While the above catalogues proved adequate for the purposes of ascertaining correct positions, there are several on-line catalogues which cover the SMC - 2MASS, DENIS and MACS. The first two in particular can be accessed using the Vizier utility at CDS, Strasbourg. Homepage is http://cdsweb.u-strasbg.fr/CDS.html, and follow the links.
221 records + notes.
The catalogue is divided into two parts - A and B.
Part A: The clusters from the lists of Kron (1956), Lindsay (1958) and Westerlund/Glaspey (1971)
Part B: The 86 small and faint clusters listed by Hodge and Wright (1974).
The format is essentially the same for both parts, as follows:
Col./Field Name Description
1 LIN : Ordinal number from Lindsay cat. (Part A)
HW : Ordinal number from HW catalogue (Part B).
2 Class : Classification of object. Key :
C = Open cluster GC = Globular cluster
C-g = cluster with superficial resemblance to a GC (often
listed as GC elsewhere).
ND = Not detected.
[Note: Lin. 10 = NGC 121 is said to be the only Pop. II GC in SMC.]
3 Id.2 : Alternative identifiers (Kron or Westerlund/Glaspey nos.)
4 Id.3 : Corresponding number in NGC and IC catalogues.
5 GSC : GSC object attributable to the cluster.
* N/A means that GSC was searched, but no attributable GSC
object was found.
[The majority of GSC objects found are classed as "non-stellar". From
time to time an individual cluster star is entered, provided it is close
to the adopted centre of the cluster.]
6 GSC Mag. : Average GSC mag., from GSC Catalog. For reference only.
7 RA (2000): Right Ascension, equinox J2000.
8 Dec(2000): Declination, equinox J2000.
9 : Source of position : DW = D.L. Welch (1991)
G = GSC 1.1 A = USNO-A2.0 E = Estimated
10,11 Size : Dimensions of cluster, (N-S and E-W), in arcmins.
Sources : BSDL for Part A clusters.
: Hodge & Wright (1974) for Part B clusters.
Note that the BSDL compilation lists diameters for the HW
clusters which appear overlarge by a factor of almost 10
in some cases. I have copied the original HW diameters,
which seem more realistic.
Hodge, P.W. and Wright, F.W. 1977. The Small Magellanic Cloud.
University of Washington Press, Seattle. [HW]
Ibid. 1974. Astron. J. 79,858.
Lindsay, E.M. 1958, Mon. Not. R. ast. Soc. 118,172 [LIN]
Kron, G.E. 1956, Publ. Astron. Soc. of Pacific, 68, 125 [K].
Welch, D. L. 1991, Astron. J. 101, 538-540.
Westerlund, B.E. and Glaspey, J. 1971, Astron. Astrophys. 10,1 [WG]
I wish to acknowledge the valuable assistance of Dave Monet, US Naval Observatory, Flagstaff, AZ, in providing the USNO-A2.0 catalogue on CD-ROM. The work done by Jenni Kay, Lobethal, South Australia, was also valuable in checking the correct identifications of clusters. Also, Dr. Harold G. Corwin Jr, Brian Skiff and Brent Archinal for help and advice in this overall project to compile better positions for MC clusters.
Compiled by M. Morel, 2001 August 1.
Identifications and J2000 positions for 220 objects.
IDENTIFICATIONS - Atlases & published lists.
[HW] : Hodge, P.W. & Wright, F.W. "The Small Magellanic Cloud",
University of Washington Press, Seattle. (1977).
Catalogue: Ibid, Astron. J. 79,858 (1974).
[LIN] : E.M. LINDSAY, 1958, Mon. Not. R. ast .Soc. 118,172.
"The cluster system of the Small Magellanic Cloud".
[K] : Kron, G.E. 1956, Publ. Astron. Soc. of Pacific, 68,125
[WG] : Westerlund, B.E. and Glaspey, J. 1971,
Astron. Astrophys., 10,1
Part A list:
BSDL : A revised and extended catalog of Magellanic system clusters,
associations, and emission nebulae. Astron. J. 117, 238 (1999)
Part B list:
Hodge,P.W. and Wright,F.W. 1974, Astron. J. 79,858
ASTROMETRY: Position code:
A = USNO-A2.0 catalogue.
DW = Douglas L. Welch 1991, Astron. J. 101,538-540.
G = Guide7 data (for GSC).
E = Estimated or evaluated position.
L = E.M.Lindsay (1958).
OBJECT TYPE (or visual appearance):
C= Open Cluster.
C-g= Open cluster - superficial globular.
GC= Globular Cluster (Pop. II).
ND= NO CLUSTER DETECTED
2001 August 1
* M. Morel, 6 Blakewell Rd, Thornton NSW 2322 Australia *
* http://www.ozemail.com.au/~morel *
Max's combined catalogue is saved as a PDF file here: https://www.asnsw.com/content.cfm?page_id=1342121¤t_category_code=21965