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COCD - COCD: Catalog of Open Cluster Data

HEASARC
Archive

Overview

The Catalog of Open Cluster Data (COCD) is a result of studies of the wide neighborhoods of 513 open clusters and 7 compact associations carried out in the high-precision homogeneous All-Sky Compiled Catalog of 2.5 Million Stars (ASCC-2.5, Kharchenko 2001, CDS Cat. <I/280>). On the basis of data on about 33,000 possible members (including about 10,000 most probable ones) and homogeneous methods of cluster parameter determination, the angular sizes of cluster cores and coronae, cluster heliocentric distances, mean proper motions, mean radial velocities and ages were established and collected in the COCD. These include cluster distances for 200 clusters, average cluster radial velocities for 94 clusters, and cluster ages for 195 clusters derived for the first time. Clusters in the catalogue are sequenced in their Right Ascension J2000 order.

The Open Cluster Diagrams Atlas (OCDA) presents a set of open cluster diagrams used for the determination of parameters of the 513 open clusters and 7 compact associations, and is intended to illustrate the quality of the constructed cluster membership (Kharchenko et al. 2004, CDS Cat. <J/AN/325/740>), and the accuracy of the derived cluster parameters. Every diagram presents relation between various stellar data from the ASCC-2.5 in the area of the specific cluster. There are five diagrams provided for every cluster in the Atlas: the area map, the density profile, the vector point diagram, the magnitude equation diagram and the color-magnitude diagram. The OCDA PostScript plots (one file per cluster) are available as a remote data product for entries in this table.


Catalog Bibcodes

2004AN....325..740K
2005A&A...438.1163K

References

Astrophysical parameters of Galactic open clusters.
    Kharchenko N.V., Piskunov A.E., Roeser S., Schilbach E., Scholz R.-D.
   <Astron. Astrophys. 438, 1163 (2005)>
   =2005A&A...438.1163K
Astrophysical supplements to the ASCC-2.5. II. Membership probabilities in 520
Galactic open cluster sky areas
    Kharchenko N.V., Piskunov A. E., Roeser S., Schilbach E., Scholz R.-D.
   <Astron. Nachr. 325, 740 (2004)>
   =2004AN....325..740K

Provenance

This table was created by the HEASARC in May 2011 based on CDS Catalog J/A+A/438/1163 files cocd.dat and notes.dat.

Data Products

The atlas files (one for each cluster) in the OCDA are stored at CDS. Each file is in a compressed PostScript format. The CDS describes these files as follows:
    Each plot contains a header, five diagrams and selected cluster
    parameters from the 1st Extension of the Catalogue of Open Cluster
    Data (COCD-1). The header gives the equatorial coordinates of the
    newly determined cluster center, the cluster number and designation in
    the file index.dat and reference to note file.

    The panels present spatial, kinematic and evolutionary information.
    The upper row: the left panel is a sky map of the cluster neighborhood
    (MAP) constructed with stars from the CDS catalog <I/280>, and the right
    panel is the colour-magnitude diagram (CMD). The bottom row: the left
    panel shows density profile diagram (DPD) - radial profiles of the
    projected density, the middle panel is the vector point diagram of
    proper motions (VPD), and the two right panels are "magnitude
    equation" diagrams (MED) - proper motions versus magnitude.

 Common designation on MAP, CMD, VPD, MED:

    Green symbols: stars within the cluster radius;
    Black symbols: the most probable (1sigma members) within of cluster core;
      Red symbols: the most probable (1sigma members) outside of the core
                   and within cluster corona.

 MAP:
      Stars are displayed as circles.
      The circle size corresponds to stellar magnitude ranged in six Vmag
      intervals: <4.0, 4.0-6.0, 6.0-8.0, 8.0-10.0, 10.0-12.0, >12.0.
     Cyan open circles: stars outside of cluster area (are shown in MAP only);
    Green open circles: stars inside of cluster area;
            Blue cross: cluster center selected in this study;
        Magenta pulses: centers of other clusters (from Dias et al., 2004)
                        visible (if any) in this map;
     Solid blue circle: cluster core border (rcore);
    Dashed blue circle: cluster border (rcl).

 CMD:
    Solid blue lines outline a domain of 100% photometric cluster members.
    - the left border is the empirical ZAMS of Schmidt-Kaler;
    - the right border is composed as it is described by Kharchenko et al.
      (2004, Cat. J/other/AN/325.740);
    For convenience blue edge is extended in comparison to the
    Schmidt-Kaler ZAMS up to MV= -7.0, (B-V)0= -0.33;
    - Solid cyan lines indicate blue and red borders of the evolved Main
      Sequence, (see Kharchenko et al., 2005A&A...440..403K for definitions);
    - Bars indicates the rms errors of V and (B-V) for 1sigma members;
      Magenta solid curves are Post- and Pre-MS isochrones closest to the
      determined cluster age;
    - Large magenta open circles mark stars selected for age determination
      (see Kharchenko et al. 2005A&A...440..403K for details).

 VPD: Bars indicate the rms errors of PM for 1sigma members.

 MED:
    - Magenta solid lines correspond to determined average proper motion
      of the cluster;
    - Bars indicate the rms errors of PM for 1-sigma members.

 DPD:
    - Green solid line is constructed for all stars in the cluster area;
    - Magenta solid line is constructed for all members with membership
      probability P>1% (i.e. 1,2,3sigma members);
    - Black solid line is constructed for 1sigma members only;
    - Solid blue line indicates cluster core radius;
    - Dashed blue line indicates cluster radius;

 Notes on selected cluster parameters shown in the CMD panel:
    - The rms errors of determined PM and RV are shown in parentheses;
    - Distance modulus corresponds to indicated d and E(B-V) values;
    - Number of stars selected for log t determination is shown after
      the 'pound' or 'hash mark' symbol;

Parameters

Source_Number
A running identification number for each cluster in order of increasing J2000.0 Right Ascension.

Name
The common name of the cluster, such as its NGC or IC designation.

Alt_Name
Another commonly used designation for the cluster, if one exists.

RA
The Right Ascension of the adopted cluster center in the selected equinox. This was given in J2000.0 coordinates to a precision of 0.001 hours (3.6 seconds of time) in the original table.

Dec
The Declination of the adopted cluster center in the selected equinox. This was given in J2000.0 coordinates to a precision of 0.01 degrees (36 arcseconds) in the original table

LII
The Galactic Longitude of the adopted cluster center.

BII
The Galactic Latitude of the adopted cluster center.

Core_Radius
The angular radius of the core of the cluster, in degrees. The authors assumed a centrally symmetric distribution of the cluster members and considered only two structural components, a core with a radius r1, and a corona with a radius r2. The core radius corresponds to the distance where the decrease of stellar surface density stops abruptly. For each cluster, the core and corona radii were checked by visual inspection, and the constraints set by the corresponding vector point diagram (VPD) of the proper motions and the color-magnitude diagram (CMD) were always taken into account.

Cluster_Radius
The angular radius of the corona of the cluster, in degrees. The authors assumed a centrally symmetric distribution of the cluster members and considered only two structural components, a core with a radius r1, and a corona with a radius r2. The corona radius (i.e. the actual radius of the cluster) is defined as the distance from the cluster centre where the surface density of stars becomes equal to the average density of the surrounding field (see Fig. 1b in the 2005 reference paper). For each cluster, the core and corona radii were checked by visual inspection, and the constraints set by the corresponding vector point diagram (VPD) of the proper motions and the color-magnitude diagram (CMD) were always taken into account.

Rad_Vel
The average radial velocity of the selected stars in the cluster, in km/s.

Rad_Vel_Error
The standard error in the average radial velocity of the selected stars in the cluster, in km/s.

Num_Rad_Vel_Stars
The number of cluster stars used for the radial velocity calculation.

PM_RA
The average cluster proper motion in the Right Ascension direction, muRA * cos(Dec), in milliarcseconds per year (mas/yr).

PM_RA_Error
The standard error in the average cluster proper motion in the Right Ascension direction, muRA * cos(Dec), in milliarcseconds per year (mas/yr).

PM_Dec
The average cluster proper motion in the Declination direction, muDec, in milliarcseconds per year (mas/yr).

PM_Dec_Error
The standard error in the average cluster proper motion in the Declination direction, muDec, in milliarcseconds per year (mas/yr).

PM_LII
The average proper motion in the Galactic Longitude direction, mulii * cos(bii), in milliarcseconds per year (mas/yr).

PM_BII
The average proper motion in the Galactic Latitude direction, mubii, in milliarcseconds per year (mas/yr).

Num_Cluster_Stars
The number of the most probable (1-sigma) cluster members. For each cluster, the membership determination was based on a comprehensive common analysis of several diagrams derived with ASCC-2.5 data: a sky chart referring to the cluster, the radial distribution F(r) of the projected stellar density, a vector point diagram (VPD) of the proper motions, the magnitude dependence of the proper motion components, and a colour-magnitude diagram (CMD).

Distance
The cluster distance, D, in parsecs (pc). The methodology used to estimate D is discussed in Section 3.1 of the reference paper.

E_BV
The reddening (color excess), E(B-V), towards the cluster, in magnitudes. The methodology used to estimate E(B-V) is discussed in Section 3.1 of the reference paper.

Distance_Modulus
The apparent distance modulus of the cluster, i.e., the quantity (5 * log (D)) - 5.0 + AV, where AV is the visual extinction towards the cluster and is assumed to be 3.1 * E(B-V).

Ref_Distance
A code for the reference for the estimated cluster distance and color excess. These codes have the following meanings:

    1 = Dias et al., 2004, Open clusters and Galactic structure,
        Version 2.0, http://www.astro.iag.usp.br/~wilton
    2 = Kharchenko et al., 2005
    3 = Loktin, 2004, Private communication
    4 = Lynga, 1987 "Catalogue of open clusters data. Fifth edition"
    5 = Robichon et al., 1999, CDS Cat. <J/A+A/345/471>
    6 = Ruprecht et al., 1981, CDS Cat <VII/31>
    7 = de Zeeuw et al., 1999, CDS Cat. <J/AJ/117/354>
  

Log_Age
The logarithm of the average age of the stars in the cluster, log t, in years. The methodology used to estimate cluster ages is discussed in Section 5 of the reference paper.

Num_Log_Age_Stars
The number of cluster stars used for the age calculation. The negative numbers for this quantity have the following meanings:

     -1 = when log t is found with the help of a star located to the left of
          the blue limit of the evolved MS,
     -2 = when log t is found with the help of a star located to the right of
          the red limit of the evolved MS,
     -3 = if log t has been set manually.
  

Lit_Rad_Vel
The average radial velocity of the stars in the cluster as taken from the literature, in km/s.

Lit_Rad_Vel_Error
The standard error in the average radial velocity of the stars in the cluster as taken from the literature, in km/s.

Ref_Lit_Rad_Vel
A code for the reference for the cluster radial velocity taken from the literature. These codes have the following meanings:

    1 = Dias et al., 2004, Open clusters and Galactic structure,
        Version 2.0, http://www.astro.iag.usp.br/~wilton
    2 = Kharchenko et al., 2005
    3 = Loktin, 2004, Private communication
    4 = Lynga, 1987 "Catalogue of open clusters data. Fifth edition"
    5 = Robichon et al., 1999, CDS Cat. <J/A+A/345/471>
    6 = Ruprecht et al., 1981, CDS Cat <VII/31>
    7 = de Zeeuw et al., 1999, CDS Cat. <J/AJ/117/354>
  

Lit_Log_Age
The logarithm of the cluster age, in years, taken from the literature.

Ref_Lit_Log_Age
A code for the reference for the cluster age taken from the literature. These codes have the following meanings:

    1 = Dias et al., 2004, Open clusters and Galactic structure,
        Version 2.0, http://www.astro.iag.usp.br/~wilton
    2 = Kharchenko et al., 2005
    3 = Loktin, 2004, Private communication
    4 = Lynga, 1987 "Catalogue of open clusters data. Fifth edition"
    5 = Robichon et al., 1999, CDS Cat. <J/A+A/345/471>
    6 = Ruprecht et al., 1981, CDS Cat <VII/31>
    7 = de Zeeuw et al., 1999, CDS Cat. <J/AJ/117/354>
  

Notes
Individual notes concerning the cluster.


Contact Person

Questions regarding the COCD database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 10-May-2011