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SMCCLUSTRS: Help

SMCCLUSTRS - SMC & Bridge Clusters Catalog


Overview

This is the Small Magellanic Cloud (SMC) and Inter-Magellanic Cloud ('Bridge') portion of the 'Revised and Extended Catalog of Magellanic System Clusters, Associations, and Emission Nebulae' (Table 2 of Bica and Schmitt 1995). A survey of extended objects in the SMC and Bridge was carried out on the ESO/SERC R and J Sky Survey Atlases and 1188 such objects were identified, including 544 classified as star clusters, 343 as emissionless associations, and 291 as emission nebulae. Only those objects which could be detected on the ESO/SERC Schmidt films as nonstellar (typically larger than 15 arcseconds) are included in this catalog, note. The catalog also includes cross-identifications with previous catalogs, and 284 newly identified objects. Accurate positions, classification, homogeneous sizes, and position angles are provided, as well as information on cluster pairs and hierarchical relations for superimposed objects.

Catalog Bibcode

1995ApJS..101...41B

References

Bica, E.L., and Schmitt, H.R. 1995, Astrophysical Journal Supplement, Vol. 101, pp. 41-85.

Provenance

This database was created by the HEASARC in February 1998 based on a computer readable version of the catalog that was obtained from the CDS (their catalog J/ApJS/101/41). Additional information for the help documentation was obtained from the published version of this catalog (Bica and Schmitt 1995).

Excluded Objects

Those 300 entries from the different extended object catalogs which were excluded from the current catalog for various reasons (stellar appearance, non-existence, being an asterism, galaxy, or suspected galaxy, object duplication in the same catalog, or an entry from an emission nebulae catalog which is a star cluster not related to emission) were listed by Bica and Schmitt (1995) in their Table 3. These excluded objects are not in the SMCCLUSTRS Catalog which is based on Table 2 of that reference, but a machine-readable version of Table 3 can be obtained at:

ftp://legacy.gsfc.nasa.gov/heasarc/dbase/misc_files/smcclustrs/excluded.dat

Notice that this list of exluded objects contains most of the known planetary nebulae in the SMC because their appearance was stellar on the Schmidt films.


Parameters

Plate_Designation
The ESO/SERC Sky Survey field and quadrant in which the object is best seen.The ESO/SERC fields studied for this catalog were 13, 28, 29, 30, 31, 50, 51, and 52. Thus a plate designation of '28NW' means that the object is in the northwest (NW) quadrant of field 28.

Name
The object name. For the 284 new objects (24% of the unified catalog), the designation 'BSn' was used, where BS stands for Bica and Schmitt, and n is a running number that is approximately ordered in right ascension, while for objects for which cross-identification in other catalogs found a counterpart, one of these was used for the name. (See acronym list below). H II regions and their embedded stellar associations of comparable extent were considered to be equivalent objects, while some objects were separated into two or more parts, and consequently have designations that are complemented with, e.g., 'N' for northern part, 'SE' for southeastern part, etc.

  Acronym List for Cross-Identifications with Previous SMC and Bridge Catalogs

  Acronym          Reference                              Entries  Object Types

  SMC-N            Henize 1956, ApJS, 2, 315                  117       N
  K                Kron 1956, PASP, 68, 125                    69       C
  L                Lindsay 1958, MNRAS, 118, 172              116       C
  WG               Westerlund and Glaspey 1971, A&A, 10, 1     18       C,A
  HW               Hodge and Wright 1974, AJ, 79, 858          86       C
  SMC-DEM          Davies et al. 1976, MmRAS, 81, 89          167       N
  B                Bruck M.T. 1976, OccRep ROE, No. 1         168       C,A
  SNR              Mathewson et al. 1983, ApJS, 51, 345         5       N
  SNR              Mathewson et al. 1984, ApJS, 55, 189         6       N
  H-A              Hodge 1985, PASP, 97, 530                   70       A
  H86-             Hodge 1986, PASP, 98, 1113                 213       C
  SMC-DEM          Meaburn 1986, MNRAS, 223, 317                5       N
  IDK              Irwin et al. 1990, AJ, 99, 191               5       A
  B-OB             Battinelli 1991, A&A, 244, 69               31       A
  BD               Battinelli and Demers 1992, AJ, 104, 1458   73       A
  BS               Bica and Schmitt 1995, ApJS, 101, 41       284       C,N,A
  

Alt_Name
Alternative name(s) for the object (see description of Name parameter for a list of the acronyms used for names).

RA
The right ascension of the object. The accuracy of the position is primarily dependent on the determination of the center of the object. For star clusters, this uncertainty is typically 10 to 15 arcseconds. For large associations and/or H II complexes, the determination of the center is less precise, but this becomes irrelevant as compared to their large extent, in any case.

Dec
The declination of the object. The accuracy of the position is primarily dependent on the determination of the center of the object. For star clusters, this uncertainty is typically 10 to 15 arcseconds. For large associations and/or H II complexes, the determination of the center is less precise, but this becomes irrelevant as compared to their large extent, in any case.

LII
Galactic longitude of the object.

BII
Galactic latitude of the object.

Object_Type
Obvious star clusters and emissionless associations are indicated by C and A, respectively. This distinction is based primarily on stellar density, but additional criteria are the magnitude distribution of stars and the occurrence of irregular shape (which latter property characterizes associations). The intermediate classes CA and AC reflect the fact that there was some uncertainty in the classification, and, in these cases, the first letter is the more probable classification. NA is used to describe H II regions with embedded associations, whereas NC is used for small H II regions with embedded star clusters and/or high-surface-brightness compact H II regions. N is reserved for known supernova renmants (Mathewson et al. 1983 ApJS, 51, 345; 1984, ApJS, 55, 189) and for a few objects which were seen as nonstellar in the Schmidt films and are classified as planetary nebulae (Meyssonier and Azzopardi 1993, A&AS, 102, 451). Finally, AN and CN are associations and clusters, respectively, which show some traces of emission.

Major_Diameter
The size (diameter) of the major axis, in arcminutes. The measurement of the sizes was carried out with a resolution of 4 arcseconds.

Minor_Diameter
The size (diameter) of the minor axis, in arcminutes. The measurement of the sizes was carried out with a resolution of 4 arcseconds.

Position_Angle
The Position Angle (P.A.) of the major axis in degrees, where 0 degrees means North and 90 degrees means East. The measurement of the position angles was carried out with a precision of plus or minus 5 degrees.

Remarks
Various remarks concerning the particular object:

   PN: planetary nebula,
   MP: member of cluster pair
   MT: member of cluster triplet
   BR*: a bright star is present
   ATT: attached to
  
A hierarchical indication is given for objects embedded in or superimposed on larger ones: IN suggests a possible connection, while SUP suggests a projection.

Class
browse classification based on the first letter of the object type.


Contact Person

Questions regarding the SMCCLUSTRS database table can be addressed to the HEASARC User Hotline.
If you have any problems, please consult the help page or mail ledas-help@star.le.ac.uk
 
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