Catalog README file:
-- CNOC2 catalogs --
Version Feb. 13, 2001 :
fixed photometric offset of 0.2-0.3 mag in a2 & a3 fields
I. General
(1) Please refer to Yee et al. (2000, ApJS, Sep; astro-ph/0004026,
hereafter Paper I) for a much more detailed explanation of
the catalog.
(2) The catalogs are sorted in R magnitude, with galaxies listed first,
and stars at the end.
(3) The 5-sigma detection limits for each field can be found in Paper I.
This is not intended as a completeness limit; the 100% completeness
is about 0.7 to 0.9 mag brighter than the 5-sigma limit. Note that
there is significant variation in the 5-sig limit from field to field.
(4) The nominal spectroscopic limit is defined at the magnitude where
the magnitude weight is about 5. Note that there is significant
variations of the nominal spectroscopic limit from field to field.
(5) An important feature of the catalog is the various weights
computed to allow the sample to be used as a complete sample. A
detailed description of the weights are given in paper I. The
primary weight is the magnitude weight Wm. The subsidiary weights
modify the magnitude weight Wm as follows:
W(tot) = Wm X Wxy X Wc X Wz,
where Wxy=geometric weight, Wc=color weight, and Wz=redshift weight.
Note that each filter has its own Wm, Wxy and Wc. However, Wz, which
is model dependent, is determined only for the R filter.
(6) The total area of the 0223 patch is 1409 square arcminutes. An array
representing the shape of the sampled area (called the field-area map)
using 1's and 0's with a resolution of 2"/pixel is available.
(7) The origin of the co-ordinate system (delta RA=0.0, delta Dec=0.0) is
02:23:29.95 +00:05:12.9 (1950)
The large-scale astrometry is good to about +-1" RMS.
(8) There is a small systematic redshift difference for emission-line
objects (Sc=5) depending on whether the redshift is obtained from
[OII]3727 or H-beta/[OIII]4959,5007. This arises from imperfect
wavelength calibration of the cross-correlation template spectra.
It will be corrected in a future version of the catalog.
II. Data Columns: Note: entries with "9" in all spaces except for the
decimal point are blank entries (no data available).
(1) pppid: last 4 digits: ppp# within each field,
first 2 digits: field number. See paper I. When discussing
objects from different patches, prepend the 4-digit patch code
followed by decimal point; i.e., 0223.062246 instead of 062246.
(2) spnum: spectrum name. The last 4 characters denote mask number,
(A,B,C) and spectrum number (e.g. A034), the first 2 numbers denote
field numbers (same as (1)). Note that for objects with multiple
observations only one of the spectrum IDs is listed (usually the one
with the highest Rval value).
(3,4) d_RA and d_Dec: Delta RA and delta Dec, both in arcsec, relative to
the central position. Positive numbers denote offsets WEST and NORTH.
Thus: RA = RA_central_position - (d_RA)/cos(DEC)
DEC = DEC_central_position + (d_Dec)
(5) z: redshift
(6) zerr: redshift error listed in units of 10^-5 in z
(7) Rval: cross correlation coefficient for redshift determination.
Normally the redshift ID is robust if Rval>4 for Sc=2 or 4, or
Rval>5 for Sc=5.
(8) Sc: spectral class from cross correlation. Sc=2: absorption line/
early type; Sc=4: intermediate-late type; Sc=5: emission line;
Sc=6: AGN; Sc=77: star; Sc=88: unknown; Sc=99: slit but no spectrum
(object too faint); Sc=0: object not targeted for spectroscopy.
(9) Wz: redshift weight (to account for the redshift limit imposed by
the band-limited spectra), applicable to the R filter. This
dependent on the luminosity function model.
(10) Imag: I magnitude. All magnitude are given in ppp total magnitude
derived based on the growth curve of the R image. See
paper I for a detailed description of the derivation of the
total magnitude of each filter.
(11) Ime: I magnitude error (for the total magnitude) expressed as a
percentage of the flux. Note that for small error (<0.15 mag), the
fractional error is equivalent to the error in magnitude. All
(total) magnitude errors include a 0.03 mag "aperture error" added
in quadrature to the photon statistic error. All errors do not
include systematic errors arising from calibration uncertainties.
An error of 800 denotes that the magnitude is a sigma sky limit.
(12) Ice: color aperture magnitude error. This is the magnitude error
within the aperture used to determine the color of the object.
An approximate uncertainty in the color between any two filters
can be derived by added the two color aperture errors in quadrature.
(13) Iwm: I magnitude weight. The magnitude weights are determined using
a sample within each field (MOS image), not the entire patch.
(14) Iwc: I color weight.
(15) Iwxy: I geometric weight.
(16) Rmag, (17) Rme, (18) Rce, (19) Rwm, (20) Rwc, (21) Rwxy: mag, mag error,
color aperture mag error, mag weight, color weight, and geometric weight,
for filter R.
(22) Vmag, (23) Vme, (24) Vce, (25) Vwm, (26) Vwc, (27) Vwxy: mag, mag error,
color aperture mag error, mag weight, color weight, and geometric weight,
for filter V.
(28) Bmag, (29) Bme, (30) Bce, (31) Bwm, (32) Bwc, (33) Bwxy: mag, mag error,
color aperture mag error, mag weight, color weight, and geometric weight,
for filter B.
(34) Umag, (35) Ume, (36) Uce, (37) Uwm, (38) Uwc, (39) Uwxy: mag, mag error,
color aperture mag error, mag weight, color weight, and geometric weight,
for filter U.
(40) Pcl: ppp star-galaxy classification: 0=cosmic ray/non detection,
1=galaxy, 2=probable galaxy, 3=star, 4=saturated star.
(41) Rkor: K-correction for the R filter derived from fitted SED.
(42) x: x pixel co-ordinate in original CCD image.
(43) y: y pixel co-ordinate in original CCD image.
(44,45,46) Right Ascension (1950): hours, minutes, seconds.
(47,48,49) Declination (1950): degrees, arcminutes, arcseconds.
Note that degrees is an explicitly signed integer.