ACDS V10.0 - Detailed Description of VII/203

ACDS V10.0 - Sun Jan 19 06:09:52 CET 2025

| # Detailed Description of VII/203 : Las Campanas Redshift Survey (Shectman+ 1996) |

Note : this is the description file of the original catalog. This HTML page corresponds well to the original description, but some minor changes in the format may have been introduced in the FITS output files in order to allow for arithmetic operations on quantities such as coordinates and times. h:m:s and d:m:s units are normally converted into degrees, and YYYY-MM-DD into julian days.
Similarly, some slight changes may have been introduced in the units; the value given in the HTML files supersedes the value indicated in the ReadMe file for this catalogue.

    VII/203                 Las Campanas Redshift Survey (Shectman+ 1996)
    ================================================================================
    The Las Campanas Redshift Survey
        Shectman S.A., Landy S.D., Oemler A., Tucker D.L., Lin H., Kirshner R.P.,
        Schechter P.L.
       <Astrophys. J. 470, 172 (1996)>
       =1996ApJ...470..172S
    ================================================================================
    ADC_Keywords: Redshifts ; Galaxy catalogs ; QSOs

    Keywords: cosmology: observations - galaxies: clusters: general -
              galaxies: distances and redshifts - surveys

    Abstract:
        The Las Campanas Redshift Survey (LCRS) consists of 26,418 redshifts
        of galaxies selected from a CCD-based catalog obtained in the R band.
        The survey covers over 700deg^2 in six strips, each 1.5x80deg, three
        each in the north and south Galactic caps. The median redshift in the
        survey is about 30,000km/s. Essential features of the galaxy selection
        and redshift measurement methods are described and tabulated here.
        These details are important for subsequent analysis of the LCRS data.
        Two-dimensional representations of the redshift distributions reveal
        many repetitions of voids, on the scale of about 5000km/s, sharply
        bounded by large walls of galaxies as seen in nearby surveys.
        Statistical investigations of the mean galaxy properties and of
        clustering on the large scale are reported elsewhere. These include
        studies of the luminosity function, power spectrum in two and three
        dimensions, correlation function, pairwise velocity distribution,
        identification of large-scale structures, and a group catalog.

    Description:
        In referencing individual galaxies within the LCRS, it is recommended
        that investigators adhere to the IAU-registered LCRS naming
        convention, as listed in the online "dictionary of nomenclature of
        celestial objects" (http://astro.u-strasbg.fr/cgi-bin/Dic), which is:
        LCRS BHHMMSS.s-DDMMSS, in which the coordinates are equinox 1950.0, RA
        is truncated (* not rounded *) to a tenth of a second, and DEC is
        truncated (* not rounded *) to a whole arcsecond.

    See also: See also the LCRS home pages at:
        http://qold.astro.utoronto.ca/~lin/lcrs.html : Las Campanas Redshift Survey

    File Summary:

           FileName      Lrecl  Records   Explanations

    ×                   80        .   This file
    × ReadMe            80        .   This file
    × fields.dat       123      327   LCRS spectroscopic fields  (Table 2)
    × catalog.dat       98    94959   Redshift catalog (Table 3)

    Byte-by-byte Description of file:  fields.dat

       Bytes Format Units   Label     Explanations

       1-  8  A8    ---     Field     Field designation (1)
      10- 11  I2    h       RA1h      First boundary field right ascension (1950.0)
      13- 14  I2    min     RA1m      First boundary field right ascension (1950.0)
      16- 20  F5.2  s       RA1s      First boundary field right ascension (1950.0)
      22- 23  I2    h       RA2h      Second boundary field right ascension (1950.0)
      25- 26  I2    min     RA2m      Second boundary field right ascension (1950.0)
      28- 32  F5.2  s       RA2s      Second boundary field right ascension (1950.0)
          34  A1    ---     DE1-      First boundary field declination sign
      35- 36  I2    deg     DE1d      First boundary field declination (1950.0)
      38- 39  I2    arcmin  DE1m      First boundary field declination (1950.0)
      41- 44  F4.1  arcsec  DE1s      First boundary field declination (1950.0)
          46  A1    ---     DE2-      Second boundary field declination sign
      47- 48  I2    deg     DE2d      Second boundary field declination (1950.0)
      50- 51  I2    arcmin  DE2m      Second boundary field declination (1950.0)
      53- 56  F4.1  arcsec  DE2s      Second boundary field declination (1950.0)
      58- 62  F5.2  mag     m1        Lower limit magnitude (2)
      64- 68  F5.2  mag     m2        Higher limit magnitude (2)
      70- 74  F5.2  mag     mcen      Faint central magnitude limit at m2 (2)
      76- 78  I3    ---     Nfib      Designates whether data was obtained with
                                       the 50- or 112-object spectrograph system
      80- 82  I3    ---     Ngal      Number of galaxies, within the geometric and
                                       photometric limits of the field, which
                                       have redshifts.
      84- 87  F4.2  ---     f         Sampling fraction (3)
      89- 98  A10 "DD-MM-YYYY" Night  Spectroscopic observations date
     100-102  I3    ---     Frame     Spectroscopic exposure number
     104-123  A20   ---     plate     Spectroscopic plate designation

    Note (1):  Field name from RA (HHMM), Dec (+DD) and a letter suffix
         "W", "E", or "M" which means west, east, or middle,
    Note (2): Photometric selection limits. Note the catalogs always contain
         objects outside the photometric limits. Isophotal magnitude m and
         central magnitudmc   of each galaxy must meet the photometric
         selection criteria m1 <= m < m2 and mc < mcen - 0.5(m2-m)
    Note (3): Fraction of objects (galaxies plus stars) with velocities,
         among those objects meeting the photometric selection limits.

    Byte-by-byte Description of file:  catalog.dat

       Bytes Format Units   Label     Explanations

       1-  8  A8    ---     Field     Field designation
      10- 15  F6.1  ---     p         Photometric catalog object number
      17- 21  F5.2  mag     mag       Isophotal magnitude
      23- 32  A10   ---     Scan      Designation of drift scan used to obtain object
                                   photometry
      34- 38  F5.2  mag     mc        Central magnitude
      40- 41  I2    h       RAh       Right Ascension (1950.0)
      43- 44  I2    min     RAm       Right Ascension (1950.0)
      46- 50  F5.2  s       RAs       [0,60] Right Ascension (may be 60.00) epoch 1950.0
          52  A1    ---     DE-       Declination sign
      53- 54  I2    deg     DEd       Declination (1950.0)
      56- 57  I2    arcmin  DEm       Declination (1950.0)
      59- 62  F4.1  arcsec  DEs       [0,60] Declination (may be 60.0) epoch 1950.0
      64- 66  A3    ---     s         ? Spectroscopic fiber designation (1)
      68- 69  A2    ---     type      ? Spectrum type (1) (2)
      71- 75  I5    km/s    cz        ? Heliocentric velocity (1)
      77- 80  I4    km/s    e_cz      ? rms uncertainty on cz
      82- 86  F5.3  ---     sf        ? Product of sampling fraction, apparent magnitude
                                    completeness, and central surface brightness
                                    completeness factors (1) (3)
      88- 92  F5.3  ---     gsf       ? Same as sf but sampling fraction is computed
                                    only in a 1000"-radius neighborhood of the
                                    galaxy (1) (4)
      94- 98  I5    km/s    cz55      ? Instrumental constraints prevent two object
                                    fibers from approaching closer than 55"
                                    on the sky (1) (5)

    Note (1): Columns "s" to "cz55" are blank if not applicable
         to a particular object
    Note (2): Spectrum type:
         * c, e, b: galaxy
           - c: velocity from cross-correlation only
           - e: velocity from emission-line fitting only
           - b: velocity from both c and e
         * *: star
         * ?: spectrum failed to yield redshift
         * nh, tc, bl: same as no spectrum attempted
              (intended spectrum not observed)
         * QS: QSO
         * PN: planetary nebula
    Note (3): See Lin et al. (1996ApJ...464...60L) for more information;
              sf = f * F * G in the notation of that paper.
         Objects should be weighted by 1/sf in statistical analyses. Only those
         galaxies meeting the photometric selection limits have an entry.
    Note (4): This attempts to account for any variable geometric sampling
         effects, e.g. the reduced spectroscopic success at field corners
         (Shectman et al. 1995, in Wide-Field Spectroscopy and the Distant
         Universe, proceedings of the 35th Herstmonceux Conference (July 1994),
         eds. S. J. Maddox & A. Aragon-Salamanca (Singapore: World Scientific),
         p. 98.). Experience with the galaxy power spectrum (Lin et al.,
         1996ApJ...471..617L) shows that using gsf instead of sf makes little
         difference, but it does not hurt to check this for your own analyses.
    Note (5): For an object without a redshift, cz55 is the velocity of its
         closest neighbor within 55", if one exists, that has a velocity. Only
         objects within the photometric limits have an entry. To assess the
         significance of this selection effect for your particular analysis,
         you can try assigning fake velocities as described in Lin et al.
         (1996ApJ...471..617L).

    Nomenclature note:
        In referencing individual galaxies within the LCRS, it is recommended
        that investigators adhere to the IAU-registered LCRS naming
        convention, as listed in the online "Dictionary of Nomenclature of
        Celestial Objects" (http://cds.u-strasbg.fr/cgi-bin/Dic), which is:

            LCRS BHHMMSS.s-DDMMSS

        in which the coordinates are equinox 1950.0, RA is truncated
        (*** not rounded ***) to a tenth of a second, and Dec is truncated
        (*** not rounded ***) to a whole arcsecond.

    History:
      * 22-Oct-1996: AAS CD-ROM series, Volume 7, Lee Brotzman [ADS]
      * 03-Feb-1997: merged fields, Patricia Bauer, [CDS]
      * 18-Apr-2010: following a remark by H. Andernach: some fields
           were apparently missing in the merged catalog; the missing
           fields were added, and 4 duplicate records were removed
          (F. Ochsenbein)
    ================================================================================
    (End)                                         Patricia Bauer, [CDS]  03-Feb-1997