The 2QZ Catalogue Format

This page provides links to the full 2QZ and 6QZ catalogues and a description of the catalogue table format.  We also provide assorted extra data (such as the position of holes in the survey), as well as describing the format of the spectra data available.

The Catalogue

The catalogue is a flat ASCII file containing the entries for each object on a separate line, so that the full 2QZ catalogue (NGP and SGP) contains 47768 lines with the 6QZ catalogue containing another 1657 lines in an identical format.  A simple ASCII format was chosen for ease of use and flexibility.  We should note that databases much larger than the current 2QZ/6QZ really require a more advanced database system to be easily accessible.

Th full combined 2QZ and 6QZ data can be found in one catalogue:

The 2QZ/6QZ catalogue

There are also catalogue files available for the 2QZ SGP and NGP strips separately (useful for mask making etc).  As well as a separate 6QZ catalogue file (SGP only):

The NGP 2QZ catalogue (gzipped)
The SGP 2QZ catalogue (gzipped)
The 6QZ catalogue (gzipped) (SGP only)
The 10k catalogue (April 2001, Superceded by the above three)

The format of the data is described in the table below and also in the 2QZ catalogue paper (paper XII).  The format entries below are based on the standard FORTRAN format descriptors.  This catalogue format has been modified to contain more information that the original catalogue format of the 10k data release (Croom et al 2001).  In particular, B1950 coordinates have been included as well as sector identifiers.
 
Field descriptor Format Description
Name a16 IAU format object name, e.g.: J010946.1-274524  The 2QZ label is omitted. i.e. full name is: 2QZ J010946.1-274524
RA(J2000) i2 i2 f5.2 Right ascension J2000 (hh mm ss.ss)
Dec(J2000) a1i2 i2 f4.1 Declination J2000 (+/-dd mm ss.s)
Catalogue number i5 Internal catalogue object number
Catalogue name a10 Internal catalogue object name (all references should be to the IAU format name).
Sector a25 Name of the sector this object inhabits
RA(B1950) i2 i2 f5.2 Right ascension B1950 (hh mm ss.ss)
Dec(B1950) a1i2 i2 f4.1 Declination B1950 (+/-dd mm ss.s)
UKST field i3 UKST survey field number
XAPM f9.2 APM scan X position (~8 micron pixels)
YAPM f9.2 APM scan Y position (~8 micron pixels)
RArad f11.8 Right ascension B1950 (radians)
Decrad f11.8 Declination B1950 (radians)
bj f6.3 bj magnitude
u-bj f7.3 u-bj colour
bj-r f7.3 bj-r colour [including r upper limits as (bj-rlim-10)]
Nobs i1 Number of observations made with 2dF
Observation #1
z1 f6.4 Redshift
q1 i2 Identification quality x 10 + redshift quality
ID1 a10 Identification
date1 a8 Observation date
fld1 i4 2dF field number x 10 + spectrograph number
fibre1 i3 2dF fibre number (in spectrograph)
S/N1 f6.2 Signal-to-noise ratio in the 4000-5000A band
Observation #2
z2 f6.4 Redshift
q2 i2 Identification quality x 10 + redshift quality
ID2 a10 Identification
date2 a8 Observation date
fld2 i4 2dF field number x 10 + spectrograph number
fibre2 i3 2dF fibre number (in spectrograph)
S/N2 f6.2 Signal-to-noise ratio in the 4000-5000A band
Additional data
zprev f5.3 Previously known redshift (Veron-Cetty & Veron 2000)
radio f6.1 NVSS radio flux (mJy)
X-ray f7.4 RASS  x-ray flux, 0.2-2.4keV (x10-13 erg s-1 cm-2)
dust f7.5 EB-V (Schlegel, Finkbeiner & Davis 1998)
comments1 a20 Specific comments on observation 1
comments2 a20 Specific comments on observation 2 

 

There are 45 seperate entries for each object (counting hh mm ss as separate entries).  Every entry  contains data, but in some cases (for example the details of a second observation when none has occured) these may just be "-" (for strings) or "0.000"  (for numerical values) if no actual data is avaliable.  Note that the observations are strictly ordered on the basis of quality, and so the best ID for a particular object will always be ID1.

Repeats

A number of objects were observed three or more times.  The third, fourth...etc entries are not include in the main catalogue file, and in many cases are of low quality (as fields were re-observed if found to have low completeness).  However, for completeness we also provide files containing all these repeat IDs (the best two IDs are always in the main catalogue file).  First there is a file containing all the repeats:

The 2QZ/6QZ repeats file

and second we have separate files for the 2QZ NGP and SGP strips and the 6QZ (SGP only):

The NGP 2QZ repeats (gzipped)
The SGP 2QZ repeats (gzipped)
The 6QZ repeats (gzipped) (SGP only)

The format of these files is as follows:
 
Field descriptor Format Description
Name a16 IAU format object name, e.g.: J010946.1-274524  The 2QZ label is omitted. i.e. full name is: 2QZ J010946.1-274524
RA(J2000) i2 i2 f5.2 Right ascension J2000 (hh mm ss.ss)
Dec(J2000) a1i2 i2 f4.1 Declination J2000 (+/-dd mm ss.s)
Catalogue name a10 Internal catalogue object name (all references should be to the IAU format name).
bj f6.3 bj magnitude
u-bj f7.3 u-bj colour
bj-r f7.3 bj-r colour [including r upper limits as (bj-rlim-10)]
z f6.4 Redshift
q i2 Identification quality x 10 + redshift quality
ID a10 Identification
date a8 Observation date
fld i4 2dF field number x 10 + spectrograph number
fibre i3 2dF fibre number (in spectrograph)
S/N f6.2 Signal-to-noise ratio in the 4000-5000A band
rep number i1 repear number of this observation (i.e. if 3, this is the third observation)
comments a20 Specific comments this observation

 
 

Sectors

A key component in the calculation of completeness, coverage, area etc.  are the sectors files.  These list all the independent regions consisting of areas made by the overlaps of 2dF pointings.  These are called sectors.  The lists of sectors are given in two files:
sgp.sectors (gzipped)
ngp.sectors (gzipped)

We do not provide a sectors file for the 6QZ.

They can use used in a number of ways, in particular to define completeness masks in an optimal way using the make_mask.f code.  Each sector is defined by a name, e.g.: S_169_170_247 where the "S" denotes sgp and the numbers denote the fields which overlap to produce this sector, in this case, 2dF fields 169, 170 and 247.  the format of the sectors file is as follows:
 
sector_name not_sector_name area n_ran sector_RA_Decs not_sector _RA_Decs

Each of the entries are described below:
 
name description
sector_name The name of the sector e.g.: S_169_170_247
not_sector_name A string defining nearby fields which do not overlap with the sector, e.g.:  NOT_169_248
area area of sector in square degrees
n_ran number of random points in Monte Carlo integration of sector area
Sector_RA_Decs positions of the field centres in RA and Dec (B1950; radians) which make up the sector.
not_sector _RA_Decs positions of the field centres in RA and Dec (B1950; radians) which are listed in the not_sector_name string.

Plate limits, holes, field centres etc.

In order to construct accurate survey masks, a user will also require the survey boundaries (on a field by field basis) and the positions of holes.  Because the input catalogue was derived in the B1950 system, all the limits and holes are also in the B1950 system.

Plate limits

The survey strips each consist of 15 UKST fields.  The RA and dec limits (in B1950 coordinates) which provide the limits within each plate are contained in the files below (in radians):

NGP plate limits
SGP plate limits
 

Holes

The holes are specified by four corners in RA and dec.  These are converted from the APM (x,y) coordinates in which the holes were originally derived.  RA and dec are in radians:

NGP holes
SGP holes
 

2dF/6dF field centres

We provide the coordinates of each of the 2dF and 6dF survey field centres.  The coordinates were defined in the B1950 system for 2dF and J2000 for 6dF.  The 2dF field centres were used in the construction of the sectors.

2dF field centres
6dF field centres

The Spectra

We provide the spectroscopic data for all the 2dF observations that constitute the 2QZ catalogue, as well as all the 6dF observations that are contained within the 6QZ catalogue.  The small number of spectra taken from other sources are not contained within the spectral database, althought their IDs and redshifts remain in the catalogue.

 Each spectrum is contained in an individual FITS file.  The FITS file names are the names of the objects followed by "a.fits", "b.fits", "c.fits" ....etc. e.g.:  J005955.9-315951a.fits (and infact, on the CD-ROM these are also gzipped by default).  The a, b, c ... indicates whether the spectrum is associated with observation 1 (a), the adopted best spectrum, or observation 2, 3, 4 ...etc.(b, c, d ...etc) (when we have made more than one observation).  They are found on the CD-ROM in the fits/ sub-directory, and are further sub-divided on the basis of RA, into directories at one hour intervals.

The spectra are not flux calibrated. We provide a simple Perl script to extract a given list of spectra from the CD called  get_fits.pl . Given a file containing catalogue entries for your selected objects this script will copy the corresponding .fits.gz files to a specified location.

We provide two varieties of FITS file.  Long and Short.

Long Format FITS

There are a number of extensions in each FITS file:

Short Format FITS

This version of the spectra contains only the primary image (i.e. Extension 0 discussed above).  This is the version available on the CD (due to space restrictions), or if the short FITS option is selected on the WWW page.  Note that bad pixels have their values set to -200 in the simple spectrum.

Composite spectra

As part of the 2QZ spectra analysis carried out by Croom et al (2002) composite spectra were constructed.  These are available here.

Observation records

We provide various observational details of the 2QZ 10k catalogue. The data are arranged by observing run (note: the name of each run is based on the date that 2dF was placed on the telescope, not the start date of a particular observation), and include exposure times, the number of 2dF fibres placed on QSO candidates and general comments on the conditions or any technical faults etc.   A plain text version of this observing log is available here:

2QZ 2dF observing log

A small number of the observation where in particularly poor conditions and were not included in the final spectral database.  These are indeicated by "NOT INC." in the comments column.

Back to 2QZ home
Back to Spectroscopic catalogue home
The 2QZ team (July 2003)