Contents of: VII/4A/./adc.doc

The following document lists the file adc.doc from catalogue VII/4A.
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                                                           SSD-T-1-0338-0098-83





             DOCUMENTATI0N FOR THE MACHINE-READABLE VERSION OF THE
              CATALOGUE OF ABELL AND ZWICKY CLUSTERS OF GALAXIES
                        (BULGARIAN ACADEMY OF SCIENCES)





                                  April, 1983





                             Contract NAS 5-27393






                                Robert S. Hill







                                 Prepared for:


                 National Aeronautics and Space Administration
                          Goddard Space Flight Center
                           Greenbelt, Maryland 20771




                                 Prepared by:


                   Systems and Applied Sciences Corporation
                       6811 Kenilworth Avenue, Suite 500
                           Riverdale, Maryland 20737






                          SECTION 1 - INTRODUCTION

A COPY OF THIS DOCUMENT SHOULD ACCOMPANY EVERY DISTRIBUTED COPY OF THE
MACHINE-READABLE CATALOGUE.

This document describes a machine-readable version of the "Catalogue of Abell
and Zwicky Clusters of Galaxies" prepared by the Bulgarian Academy of Sciences.
This catalogue consists of three files, as follows:


     File 1  -   Abell Clusters (Abell 1958)
     File 2  -   Zwicky Clusters (Zwicky et al. 1961-68)
     File 3  -   Zwicky Plate Number Cross-Identifications (Zwicky et al.
                 1961-68)


Files 1 and 2 contain some calculated quantities as well as the data from the
published versions of the catalogues.  File 3 connects the sequential numbering
of the Zwicky clusters in file 2 with Zwicky's own field and cluster numbers.

The Abell clusters are rich, compact clusters of galaxies identified by G. O.
Abell.  From these he selected a statistical sample for inferences about the
distribution of galaxies in space.  These clusters were identified on the red
plates of the Palomar Observatory Sky Survey (POSS).

The Zwicky clusters were identified by F. Zwicky in 560 POSS fields.  They are
rich clusters, each having at least 50 members within 3 magnitudes of the
brightest member.




REFERENCES:


Abell, G. O. 1958, Astrophys. J. Suppl. 3, 211.
Corwin, H. G. 1974, Astron. J. 79, 1356.
Hill, R., Documentation for the Machine-Readable Version of the Catalogue of
     Galaxies and of Clusters of Galaxies: Data on Individual Galaxies, SASC,
     Document #SSD-T-1-5069-022-82.
Kalinkov, M., Stavrev, K. and Kaneva, I. 1975, Astron. Zh. (Letters) 1, no. 2,7.
de Vaucouleurs, G., de Vaucouleurs, A., Corwin, H. G. 1976, Second Reference
     of Bright Galaxies (Austin, University of Texas).
Zwicky, F., Herzog, E., Wild, P., Karpowicz, M. and Kowal, C. T. 1961-68,
     Catalogue of Galaxies and of Clusters of Galaxies (Pasadena, California
     Institute of Technology, 6 vols.).









                                    1-1

                          SECTION 2 - FILE CONTENTS




A byte-by-byte description of the contents of the catalogue is given in Tables
2-1, 2-2 and 2-3.  The information in the "Description" column is derived mainly
from the published version of the catalogue whenever possible.  The "Suggested
Format" column is for Fortran-formatted reads.

Table 2-1 File Contents (1 of 3): Abell Clusters

Bytes                        Description                        Suggested
                                                                Format

 1              Blank                                            1X

 2- 5           Abell cluster number (1...2712). The data in     I4
                the following fields are taken from the original
                published catalogue: Abell cluster number (bytes
                2-5), sample-cluster flag (byte 7), magnitude of
                tenth-brightest member (bytes 25-28), distance
                group (byte 31), and richness group (byte 34).
                All other data are calculated.

 6              Blank                                            1X

 7              '2' if the cluster was included in Abell's stat- I1
                istical sample, '1' if it was not.

 8              Blank                                            1X

 9-22           Equatorial coordinates (1950)
                9-10   Hours of right ascension                  I2
                11     Blank                                     1X
                12-15  Minutes of right ascension                F4.1
                16     Blank                                     1X
                17     Sign of declination                       A1
                18-19  Degrees of declination                    I2
                20     Blank                                     1X
                21-22  Arc minutes of declination                I2

23-24           Blank.                                           2X

25-28           Magnitude  of  the  tenth  brightest  cluster    F4.1
                member.   Measured on Palomar Observatory
                Sky Survey (POSS) red (E) plates, by comparison
                with calibrated galaxy images.

29-30           Blank.                                           2X




                                    2-1

Table 2-1. File Contents (2 of 3): Abell Clusters

31              Distance group; based on the magnitude of the    I1
                tenth-brightest cluster member (bytes 25-28),
                as follows:
                  Distance Group       Magnitude Range
                        1                 13.3-14.0
                        2                 14.1-14.8
                        3                 14.9-15.6
                        4                 15.7-16.4
                        5                 16.5-17.2
                        6                 17.3-18.0
                        7                 Over 18.0
                The magnitude interval is approximately 3.5
                times the standard error in magnitude estimate.

32-33           Blank.                                           2X

34              Richness group; the corresponding galaxy counts  I1
                are as follows:
                    Richness Group       Counts
                        0                 30-49
                        1                 50-79
                        2                 80-129
                        3                130-199
                        4                200-299
                        5                300 or over
                The richness-group intervals are about 3 1/2
                times the standard error in counts.

35-36           Blank.                                           2X

37-49           Galactic coordinates (system II).
                37-42      Galactic longitude (degrees).         F6.2
                43         Blank.                                1X
                44-49      Galactic latitude (degrees).          F6.2


50-51           Blank.                                           2X

52-74           Lambert    coordinates.     The    Lambert
                transformation is an equal-area projection.
                52-58      Lambert  distance  RL from  the       F7.4
                           nearest galactic pole, defined by
                           RL = 2 sin ((90-b)/2)
                           RL > 0 in north galactic hemisphere
                           RL < 0 in south galactic hemisphere
                59         Blank.                                1X
                60-66      X Lambert coordinate:                 F7.4
                           XL = 2 sin l sin ((90-b)/2)
                           Directed towards l = 90 deg for both
                           the north and the south galactic
                           hemispheres.
                67         Blank.                                1X

                                    2-2

Table 2-1. File Contents (3 of 3): Abell Clusters

                                                                 Suggested
Bytes                        Description                         Format

                68-74      Y Lambert coordinate:                  F7.4
                           YL = 2 cos l sin ((90-b)/2)
                           Directed towards l = 0 deg for both
                           the north and the south galactic
                           hemispheres.

75-76           Blank.                                            2X

77-89           Supergalactic  coordinates  according  to  de
                Vaucouleurs's new system (de Vaucouleurs et al.
                1976, p. 8).   (References follow Section 1
                above.)   The origin of longitude is at the
                ascending node of the supergalactic equator
                with the galactic equator.  These coordinates
                are calculated from the galactic coordinates.
                77-82      Supergalactic longitude (degrees).     F6.2
                83         Blank.                                 1X
                84-89      Supergalactic latitude (degrees).      F6.2

90-91           Blank.                                            2X

92-95           Corrected Abell cluster radius in degrees,        F4.2
                assuming a Friedman cosmology with
                deceleration parameter 1:
                                       2
                RAD = 0.02862 * (1 + z)  / z

96-97           Blank.                                            2X

98-103          Cluster area in square degrees, computed from     F6.3
                bytes 92-95.

104-105         Blank.                                            2X

106-109         Mean apparent population, in galaxies per         I4
                square degree, which is a measure of the mean
                surface density of cluster galaxies, defined as
                population/area.

110-111         Blank.                                            2X

112-130         Distance to cluster in megaparsecs. Computed
                for Hubble constant H = 100 km per second per
                megaparsec.
                 112-114    Radial distance RH.                   I3
                 115-116    Blank.                                2X
                 117-120    X component of RH:                    I4
                            XH = RH * cos b sin l
                 121        Blank.                                1X
                 122-125    Y component of RH:                    I4
                            YH = RH * cos b cos l
                 126        Blank.                                1X
                 127-130    Z component of RH:                    I4
                            ZH = RH * sin b

                                    2-3

Table 2-2. File Contents (1 of 2): Zwicky Clusters

                                                                 Suggested
Bytes                        Description                         Format

 1               Blank                                              1X

 2- 5            Cluster number (1...9134).  This file is in        I4
                 ascending order by right ascension (bytes 8-14),
                 whereas the original published catalogue is
                 sorted by the survey field number.  File 3 of
                 this machine-readable version (see Table 2-3) is
                 a cross-index between the two systems.

                 The data in bytes 8-44 are from the original
                 published catalogue (Zwicky et al.); all other
                 data are calculated.

 6- 7            Blank.                                             2X

 8-22            Equatorial coordinates (1950).
                 8-9         Hours of right ascension.              I2
                 10          Blank.                                 1X
                 11-14       Minutes of right ascension.            F4.1
                 15-16       Blank.                                 2X
                 17          Sign of declination                    A1
                 18-19       Degrees of declination.                I2
                 20          Blank.                                 1X
                 21-22       Arc minutes of declination.            I2

23-25            Blank.                                             3X

26               Type:  1 for open, 2 for medium compact, or 3      I1
                 for compact cluster.

27-29            Blank.                                             3X

30-33            Population of cluster (number of galaxies).        I4

34-36            Blank.                                             3X

37-40            Diameter of cluster (centimeters).                 F4.1

41-43            Blank.                                             3X

44               Distance group:   1 for near, 2 for medium         I1
                 distant, 3 for distant, 4 for very distant, or 5
                 for extremely distant cluster.

45-47            Blank.                                             3X

                                    2-4

Table 2-2. File Contents (2 of 2): Zwicky Clusters

                                                                 Suggested
Bytes                        Description                         Format


48-61           Galactic coordinates (system II).
                48-53       Galactic Longitude (degrees).           F6.2
                54-55       Blank.                                  2X
                56-61       Galactic Latitude (degrees).            F6.2

62-64           Blank.                                              3X

65-89           Lambert    coordinates.   The  Lambert
                tranformation is an equal-area projection. See
                also Table 2-1, bytes 52-74.
                65-71      Lambert  distance  RL  from  the         F7.4
                           nearest galactic pole, defined by
                           RL = 2 sin ((90-b)/2)
                           RL> 0 for north galactic hemisphere
                           RL< 0 for south galactic hemisphere
                72-73      Blank.                                   2X
                74-80      X Lambert coordinate:                    F7.4
                           XL = 2 sin l sin ((90-b)/2)
                81-82      Blank.                                   2X
                83-89      Y Lambert coordinate:                    F7.4
                           YL = 2 cos l sin ((90-b)/2)

90-92           Blank.                                              3X

93-106          Supergalactic  coordinates  according  to  de
                Vaucouleurs's new system (de Vaucouleurs et al.
                1976, p. 8).  The origin of longitude is at the
                ascending node of the supergalactic equator
                with the galactic equator.  These coordinates
                are calculated from the galactic coordinates.
                93-98     Supergalactic longitude (degrees).        F6.2
                99-100    Blank.                                    2X
                101-106   Supergalactic latitude (degrees).         F6.2

107-109         Blank.                                              3X

110-113         Cluster radius (degrees): 0.09326 * diameter.       F4.2
                (See bytes 37-40.)

114-116         Blank.                                              3X

117-122         Cluster  area (square  degrees):    0.02733 *       F6.3
                diameter squared. (See bytes 37-40.)

123-125         Blank.                                              3X

126-130         Mean apparent population (galaxies per square       I5
                degree): population/area. (See bytes 30-33 and
                bytes 117-122).

                                    2-5

Table 2-3. File Contents (1 of 2): Cross Index

                                                                 Suggested
Bytes                        Description                         Format


 1               Blank.                                             1X

 2- 5            Cluster  number (1-9134).  This  file is in        I4
                 ascending order by right ascension (bytes 8-14),
                 as file 2 of this catalogue (see Table 2-2).
                 This file cross-indexes the sequential cluster
                 number (this field) to the Zwicky plate-area
                 numbers.

 6- 7            Blank.                                             2X

 8-22            Equatorial coordinates (1950).
                 8-9         Hours of right ascension.              I2
                 10          Blank.                                 1X
                 11-14       Minutes of right ascension.            F4.1
                 15-16       Blank.                                 2X
                 17          Sign of declination                    A1
                 18-19       Degrees of declination.                I2
                 20          Blank.                                 IX
                 21-22       Arc minutes of declination.            I2

23-24            Blank.                                             IX


25-130           Zwicky plate numbers and cluster numbers
                 within the plates. This field has space for up to
                 twelve plate number-cluster number pairs, since
                 a cluster will often spread into several plate
                 areas.  These pairs are sorted in increasing
                 order of plate-area number and run from left to
                 right.  The plate-area numbers are those used
                 by Zwicky et al. For a cross-reference between
                 Zwicky  plate-area  numbers  and  Palomar
                 Observatory  Sky  Survey  (POSS)  plate-area
                 numbers, see Hill (1982). (References follow
                 Section 1 above.)
                 25-27      Lowest-numbered    plate    area        I3
                            containing cluster.
                 28         Blank.                                  1X
                 29-31      Cluster number within plate area.       I3
                 32-33      Blank.                                  2X
                 34-36      Next-lowest-numbered plate area         I3
                            containing cluster (blank if none).
                 37         Blank.                                  1X



                                    2-6

Table 2-3. File Contents (2 of 2): Cross Index

                                                                 Suggested
Bytes                        Description                         Format

                 38-40      Cluster number within plate area        I3
                            (blank if none).
                 41-130     Remaining plate-area and cluster        10(2X,I3,1X,
                            numbers, in increasing order of            I3)
                            plate area:   filled from left to
                            right.  Fields  without  numbers
                            contain blanks.












































                                    2-7

                      SECTION 3 - FILE CHARACTERISTICS


 The information in this section describes the logical structure of the
 catalogue file or files.  (Multiple values for an entry describe the
 separate files of a multi-file catalogue.)  A reminder to the user is
 included of the physical tape attributes of which knowledge may be
 required to read a tape copy of the catalogue.

Table 9-1. File Characteristics

           Catalogue Abbreviation                            AZCL
           Number of Files                                      3
           Logical Record Length (Bytes)              130,130,130
           Record Format (IBM OS/JCL)                       Fixed
           Total Number of Logical Records         2712,9134,9134

 Other attributes of the tape will vary from copy to copy, as their values
 are discretionary, or else depend on the computer for which the tape was
 copied.  These include the following:

           Number of Tracks
           Density (Bits per Inch)
           Blocksize (Bytes)
           Blocking Factor (= Number of Logical Records per Block*)
           Total Number of Blocks
           Character Code

 The values of these parameters for your tape are supplied separately.
 You may wish to write them in above.























                                     3-1

                    SECTION 4 - REMARKS AND MODIFICATIONS


 The Catalogue of Abell and Zwicky Clusters of Galaxies was received by
 the Astronomical Data Center (ADC), NASA Goddard Space Flight Center,
 from the Centre de Donnees Stellaires (CDS) in 1979.  The catalogue had
 been prepared originally by the Bulgarian Academy of Sciences.  As
 received, the catalogue contained a file of documentation in addition to
 the three data files.  Section 2 of this document merely expands on that
 documentation file.  The only modifications to the catalogue format made
 at the ADC are as follows:


 (1) The sign of declination was moved so that it always appears in the
     same byte (all three files).

 (2) The declination of Zwicky cluster no. 2343 was given as -2 deg 21
     arcmin and the type as 6, due to transposition of digits; the correct
     values are -2 deg 26 arcmin and 1, respectively.  This correction was
     made to file 2, and to file 3 as well, since the incorrect
     declination had been carried over there.




REFERENCES:   See Section 1.





























                                    4-1

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