CFA (G0): 1990 Harvard-Smithsonian CfA Redshift Catalog (19930505)
FILES:
File Velocity Range #Objects
cfa_zcat.g0 V < 99999 km/s 22744
cfa_zbig.g0 V > 99999 km/s 333
CONTENTS: 1990 Harvard-Smithsonian Center for Astrophysics (CfA) Redshift Catalog
DATASET: These files come in HyperSky dataset G-10, version 19930505. Availability on HyperSky CD-ROM: Vol. 1 (1993)
DESCRIPTION: These datafiles contain a total of 23077 galaxies and quasars from the Harvard-Smithsonian Center for Astrophysics Redshift Catalog by John P. Huchra et al., dated 5 May, 1990. The HyperSky catalog files are based on the machine-readable version of the catalog, as provided on the NASA/GSFC Astronomical Data Center (ADC) cd-rom "Selected Astronomical Catalogs", Volume 1.
The CfA redshift catalog is composed of data from several contributing catalogs of redshifts. Significant among these are the complete "North Zwicky Forty" (~2400 galaxies), the complete "Bright Galaxy Redshift Catalog" (~1350 galaxies), parts of the Southern Galaxy Redshift Survey (da Costa et al, 1987), all of the Nearby Galaxy Catalogue (Tully and Fisher, 1987), and all published data for galaxies in the CFA Redshift survey extension to mZw 15.5 (Huchra et al, 1990). A thorough discussion of the composition of the CfA catalog can be found in file REDSHIFT.DOC, by J.P. Huchra, which accompanies the catalog data on the ADC cd-rom.
The HyperSky catalog files retain the organization of the CfA catalog as presented on the ADC cd-rom: a large file containing extended infor- mation on galaxies with measured recessional velocities < 99999 km/sec, and a much smaller file containing basic information on galaxies and quasars with measured recessional velocities > 99999 km/sec.
The HyperSky catalog files do NOT retain all CfA catalog entries. Entries excluded from the HyperSky catalog files include the following:
1. CfA entries marked as private data, not useable without author permission.
2. CfA entries without velocities, included in the CfA catalog for observation planning purposes.
3. CfA entries identified as NOT extragalactic, including such entries as globular star clusters, planetary nebulae, plate flaws, etc.
Thus, HyperSky file CFA_ZCAT.G0 contains 22744 of the 38909 CfA entries, and HyperSky file CFA_ZBIG.G0 contains 333 of the 339 CfA entries.
DATA: The HyperSky data files contain the following data from the CfA catalogs:
MAG: the object magnitude from one of a number of sources. Usually it is the B(0)-Zwicky system magntidue (Huchra 1976). The BT magnitude, or total (asymtotic) magnitude in the B-system, is also provided when available in the comments following the object identification line (see below).
IDENTIFICATION: The common object name. For brighter objects this can be an NGC or IC number. For other objects, a more general name of the form HHDD+DDMM is used, where HHDD is the 1950 RA and +DDMM is the 1950 declination. Additional identifications may appear in the comments following the object identification line, as discussed below.
COMMENTS: The comment lines contain the following information, provided if available for each object. Line descriptions beginning with "**" can appear in either CfA catalog file; line descriptions starting with '*' can appear only in catalog file cfa_zcat.g0:
* A line with possibly several comma-separated fields describing the object type. If all fields are present, this line will have the following general form:
morphology, axb, luminosity-class, peculiarities
morphology: object type or description. Codes include the following:
compact E; E/dwarf E; E/S0; L-/SO-; L/SO; L+/SO+;
SO/a; Sa; Sab; Sb; Sbc; Sc; Scd; Sdm; Sm; Im/Irr I;
peculiar, Irr II; S... / Sc-Irr. Other self-explanatory comments may also appear.
axb: for spirals only, one of the 3 letters A,X,B:
A: non-barred; X: mixed; B: barred
luminosity-class: The luminosity class in the van den Bergh (1960a,b) system (Roman numerals) is provided for later-type spirals and irregular galaxies where possible.
Van den Bergh luminosity classes give an indication of the absolute magnitude of a spiral galaxy. In general, the more luminous a galaxy is, the better developed its spiral structure will be. For irregular galaxies without spiral structure, the average surface brightness is an indicator of absolute magnitude. Galaxies with the strongest, most coherent spiral structures are assigned luminosity classes of "I", and typically have absolute magnitudes around -21 (varies somewhat with morphological type). Faint, low surface brightness irregular galaxies are assigned luminosity classes of "V". Their average absolute magnitudes are around -15, but the range in this figure is large. Spirals of intermediate brightness are assigned luminosity classes of II, II-III, III and so on. M51 is a good example of a giant spiral with a luminosity class of "I". IC 1613, a dwarf irregular in the Local Group, has a luminosity class of "V".
peculiarities:
Brief comments on the presence of multiple nuclei, rings, etc. In general, only a subset of the above fields will be present for any given object.
* A line showing object dimensions in the form Dxd, followed by one of the following: "(arc sec), '(arc min), or deg(degrees).
** A line showing the heliocentric radial velocity and redshift, having the general form:
v=NNNNN(EEE) km/s z=X.XX
NNNNN: The radial velocity in km/sec. Positive values indicate recession and negative values indicate approach. For high-velocity objects in file cfa_zbig.g0, the radial velocity has been calculated from the redshift z(below) using the relation v = z * c, where c is the speed of light (299792 km/sec).
(EEE): The error associated with the radial velocity, if known. Units are km/sec.
X.XX: The object redshift. For the low-velocity objects in file cfa_zcat.g0, the redshift has been calculated from the radial velocity using the relation z = v / c, where c is the speed of light (299792 km/sec). z is not shown if z < 0.01.
* A line starting with "dis=" showing the object distance in millions of light-years (MLY). This value is converted from the CfA value in Megaparsecs (Mpc) using the relation MLY = 3.26 * Mpc.
* A line starting with "BT=" showing the B(t), or total (asymtotic) magnitude in the B-system. This is the standard magnitude used in major galaxy catalogs such as RC2 and RC3. BT magnitudes are usually about 0.4 mag brighter than B(0)-Zw magnitudes.
** CfA comments, up to 30 characters. These may contain alternate object identifications which will occasionally be cryptic. However, since no further explanation for these is offered in the CfA cd-rom documentation, none can be offered here either.