ZCAT: Help

Overview

The data presented here have primarily been assembled for the purpose of studying the large scale structure of the universe, and, as such, are nearly complete in redshift information, but are not necessarily complete in such categories as diameter, magnitude, and cross-references to other catalogues.

Catalog Bibcode

References

Provenance

Notice

If you have any further questions (and are in dire need of answers), address them to John Huchra <huchra@cfa.harvard.edu>

Parameters

Name
The name of the object, usually given as a combination of its RA and Dec coordinates.

RA
The Right Ascension of the object. In the original table this was given in 1950 equator to a precision of 0.1 seconds of time.

Dec
The Declination of the object. In the original table this was given in 1950 equator to a precision of 1 arcseconds.

LII
The Galactic longitude of the object.

BII
The Galactic latitude of the object.

Bmag
The magnitude of the galaxy, preferentially on the B(0)-Zwicky system (Huchra 1976, AJ, 81, 952). Magnitudes are taken preferentially from the 1st Reference Catalogue of de Vaucouleurs - B(0), Harvard Corrected, and then from the Zwicky Catalog. B(0) magnitudes are given a source designation (the parameter ref_bmag) of "0", Harvard Corrected magnitudes are given one of "2", and Zwicky catalog magnitudes are given one of "1." Magnitudes from other sources (see the help for ref_bmag for a complete listing) are used only when necessary and available. This choice of system maximizes the number of galaxy magnitudes available and will allow for easy conversion to other systems given diameter and morphological type information (for example, the BT system).

Redshift
The redshift of the object (only given for the large redshift subset taken from the zbig.dat table).

Radial_Velocity
The radial velocity in km/sec. The velocities quoted are heliocentric, and redshifts (z's) have been converted to velocities with the conversion v equals (z * c), where c equals 299,792.5 km/sec.

Objects listed in the catalog which have no velocity and no listed velocity source (in the northern hemisphere) will be observed as part of the CfA survey extension.

Radial_Velocity_Error
In general, the errors listed for velocities are the errors quoted by the original source, i.e., random errors are quoted and systematic ones are neglected. The only exceptions are where multiple measurements have significantly improved the velocity precision. A small number of the velocities are listed with the notation "poor velocity." Those are weak cross-correlation velocities or velocities from single emission lines that need to be treated with some caution, although they are likely to be nearly correct.

Ref_Bmag
The reference code for the B magnitude value according to the following rubric:

     0 = Blank   B(0) 1ST Reference Catalogue
     1 = Zwicky Catalogue
     2 = Corrected Shapley-Ames
     3 = Tully and Fisher
     4 = J. Graham
     5 = Markarian, other Russian estimates
     6 = BT - 2ND Reference Catalogue
     7 = MCG (Vorontsov-Velyaminov))
     8 = CCD Blue
     9 = Observers eye estimates (blue)
     A = Corrected Blue magnitudes from the RC3
     B = Photoelectric or Photographic blue
     C = Eye estimates from the Case Low dispersion survey
     D = Dartmouth Red instrumental
     E = PDS magnitudes calibrated to Kron-Cousins red
     G = STScI Guide Star Catalogue (V or J)
     H = Zwicky Mag for multiple systems split by JPH
     I = CCD I
     J = Photographic J, IIIa-J
     L = SSRS2 Magnitude from L. DaCosta (approx BT)
     P = PGC magnitude
     S = Gunn red magnitude
     R = Photographic of Photoelectric R, IIIa-F, O-98 or 103aE
     T = Dressler's eye estimate (visual)
     V = Photographic or Photoelectric V
     W = CCD V
  

Note that, to avoid mixing upper and lower cases, the HEASARC has changed some of these codes from the original CDS table: values of 'd' were changed to 'E', 'r' to 'S', and 'v' to 'T'.

Ref_Radial_Velocity
Identification code for the source of the data listed for velocities. The key to the source listing for Basic Radial Velocity Sources (using just the first two characters of this code) is given below. Velocities with negative source designations are still in the private domain and should not be used without consent from the appropriate owner. The full list of references corresponding to all 4 characters of this code is available at: ftp://cdsarc.u-strasbg.fr/pub/cats/VII/193/zsource.tex (or zsource.dat).

   Basic Radial Velocity Sources
     00 = Blank  2ND REF CAT, de Vaucouleurs et al.
     01 = Sandage and Tammann (CDS/ADC Cat. VII/51)
     02 = Tully and Fisher (Nearby Galaxy Catalog, CDS/ADC Cat. VII/145)
     03 = Huchra-KPNO, (including Markarian list)
     04 = Rubin, Ford, Kinmann
     05 = Other Russian ( Byurakan, Alam-Alta, SAO)
     06 = Arecibo 21 cm - Salpeter et al., Giovanelli and Haynes
     07 = Martin
     08 = German  21cm (Bonn)
     09 = NRAO, VLA 21cm
     10 = CTIO
     11 = KPNO
     12 = ESO
     13 = HCO - M. Davis
     14 = E. Turner
     15 = Steward Observatory  - Tifft, Gregory
     16 = Rood, Chincarini, Kinter, Dickel
     17 = AAT + Mt. Stromlo
     18 = SAO - 6-meter Karachentsev, Kopylov
     19 = Texas - McDonald Observatory
     20 = Mt. Wilson - HMS, Rudnicki, Zwicky
     21 = Lick
     22 = French 21sm -- Nancay
     23 = British Optical -- I.N.T., Herschel Telescope
     24 = Palomar - Hale Telescope, Mayer telescope
     25 = Australian 21cm - Parkes
     26 = Dutch 21cm
     27 = Mt. Hopkins - CfA Redshift Survey, MMT
     28 = British 21cm  (Jodrell Bank, etc.)
     29 = Argentina - Sersic
     30 = Thuan, Seitzer, Knapp (21-cm dwarf surveys)
     31 = South Africa - SAAO -- Fairall
     32 = Arecibo - Sullivan, Bothun, Schommer
     33 = H.J. Rood - NSSDC Catalog
     34 = Ohio + Penn State
     35 = Other Optical (eg.Calar Alto, Wise, Tartu) % LaPalma
     36 = Las Campanas (100", 40"),Other Southern
     37 = Palumbo, et al. (Catalogue of Redshifts)
     38 = ESO-21cm Catalog
     39 = Brazil - Southern Survey, L. daCosta
     40 = MIT-Dartmouth-Michigan Surveys (McGraw Hill)
     41 = Hawaii - CFHT, etc.
     42 = Dartmouth - Century Survey
     43 = Davis and Strauss IRAS Sources (Published)
     44 = Hewitt and Burbidge QSO Catalog
     45 = Keck
     46 = Redshiftless entries (discoveries, companions...)
     47 = QDOT survey references
     48 = Master file data
     49 = Bothun, Moulf, published velocities; priv. comm.
     -9 = SAAO, Menzies; Fairall, Vettolani and DaCosta
     -8 = Dartmouth, not yet published
     -7 = CFA, not yet published (Kirshner)
     -6 = Brazil (L. daCosta) not yet published
     -5 = Davis and Strauss (IRAS Sources)
     -4 = Bothun, Mould not yet published (Palomar, Arecibo)
     -3 = CFA, not yet published (Forman and Jones)
     -2 = CFA, not yet published   MMT Observations (JPH)
     -1 = CFA, not yet published  Tillnghast Observations (JPH)
  

Morph_Type
Morphological types are de Vaucouleurs' T types from the RC2, Uppsala Catalog, and the Revised Shapley-Ames Catalog. Some additional types have been defined for peculiar and untyped objects, and for objects that are in catalogs of extragalactic objects but are really galactic in nature. Such objects were retained to prevent their inclusion in future lists of galaxies; however, users should filter out objects of morph_type greater than 20 before using this catalog as a simple catalog of galaxies in order to avoid getting HII regions in M101, stars, plate flaws, and assorted galactic items. Types for southern galaxies come from both the ESO catalog and the Vorontsov-Velyaminov Catalogues. The morphological type has been used to create the HEASARC Browse class parameter. The rubric for these types is:

     -9 = QSO/AGN, usually at high redshift
     -7 = Unclassified Elliptical
     -6 = Compact Elliptical
     -5 = E, and  dwarf E
     -4 = E/SO
     -3 = L-, SO-
     -2 = L, SO
     -1 = L+, SO+
      0 = SO/a, SO-a
      1 = Sa
      2 = Sab
      3 = Sb
      4 = Sbc
      5 = Sc
      6 = Scd
      7 = Sd
      8 = Sdm
      9 = Sm, Magellanic Spiral
     10 = Im, Irr I, Magellanic Irregular, Dwarf Irregular
     11 = Compact Irregular, Extragalactic HII Region
     15 = Peculiar, Unclassifiable
     16 = Irr II
     20 = S..., Sc-Irr, Unclassified Spiral
     24 = Open Star Cluster
     25 = Plate Flaw, Star, etc. misclassified as galaxy!
     26 = T Tauri star (from IRAS Surveys)
     27 = Globular Cluster
     30 = Planetary Nebula
     31 = Dark Cloud (no object visible on POSS)
     32 = HII region in external galaxy
     33 = Reflection Nebulosity
     40 = Indiv. Comp. of Multiple Nucleus Galaxy
  

Bar_Type
The bar type: possible values are 'B' (barred), 'A' (unbarred), and 'X' (for AB or mixed type). The bar type information is also included in the HEASARC Browse class parameter.

Luminosity_Class
The luminosity class (L) for spiral and irregular galaxies according to the following rubric:

       1   I                         6   III-IV
       2   I-II                      7   IV
       3   II                        8   IV-V
       4   II-III                    9   V
       5   III
  

Structure
A parameter giving additional information about peculiarities in the structure, coded as follows:

       P = Peculiar
       S = S-shaped
       R = Outer ring
       I = Inner ring
       M = Mixed (Inner ring/S-shaped)
       T = Pseudo outer ring
       D = Double or Multiple
       Q = Spindle
  

Diameter_1
The major diameter of the galaxy, in arc minutes, from the blue Palomar Sky Survey or the ESO quick blue survey a la Nilson, ESO, VV, or the RC2.

Diameter_2
The minor diameter of the galaxy, in arc minutes, from the blue Palomar Sky Survey or the ESO quick blue survey a la Nilson, ESO, VV, or the RC2.

Bt_Mag
The B_T magnitude, when available. These are generally about 0.4 magnitudes brighter than magnitudes on the B(0) - Zw system.

UGC_Or_ESO
The identification number from either the UGC (CDS Cat. VII/26) or the ESO/Upp (CDS Cat. VII/34) catalogs.

Distance
Distance in Mpc from velocity-independent distance measures. These numbers are somewhat(!) uncertain, so that the catalog is not complete and may be out of date at any time, according to the catalog authors.

Rfn_Number
The RFN parameter contains the file number of the spectrum obtained by Huchra et al. for that galaxy. If this parameter is blank, then the galaxy has not yet been measured by Huchra et al.

Comments
Most often, the `comments` field contains other names and/or other catalog designations for the object, but it may also contain some general comments, such as "poor velocity," when applicable.

Zcat_Index

Class
The Browse classification flag for the object. It includes the morphological type and bar type as applicable.

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