2QZ Basics

This page provides, in brief, some basic information on the 2dF QSO Redshift Survey (2QZ).

Survey area

The 2QZ survey covers two 75° × 5° declination strips.  One near the South Galactic Pole at declination=-30° in the range RA=21h40 to 03h15 (the SGP strip) and a second in an equatorial strip (declination=0°) near the North Galactic Pole in the region RA=09h50 to 14h50 (the NGP or equatorial strip).  The plot below shows the position of the strips on the sky, as well as the positions of all previously known QSOs (black points; Veron-Cetty & Veron 2000).

2QZ survey regions

This survey area was tiled with an overlapping mosaic of 2dF fields, designed to obtain maximum coverage from the minimum number of 2dF pointings.  The list of field names and their centres can be found here. Note that the survey was constructed in a B1950 coordinate system.

Magnitude and colour limits

The 2QZ is flux limited in the bJ band. Magnitudes were determined from APM scans of UKST photgraphic plates.  The survey limits are 18.25<bJ<20.85, with the brighter 6dF QSO Redshift Survey (6QZ) being limited to 16.0<bJ<18.25, and observed with 6dF on the UKST.  Colour selection was made in the u-b vs. bJ-r plane. In the plot below, QSO candidates are all those points below or left of the dotted line. Large blue points are previously known QSOs.

ubr colour selection

2dF Observations

The survey was carried out at the Anglo-Australian Telescope using the 2-degree Field multi-object spectrographic system.  Up to 400 spectra can be obtained at once using this state-of-the-art instrument. This huge multiplex gain has allowed surveys such as the 2QZ to become a reality.

2dF and the AAT primary
2dF on the AAT with the primary mirror in the background.

2dF on the AAT
2dF at the AAT prime focus.  The two spectrographs are located on the outer rim of the top end ring.

2dF field plate
A 2dF field plate configured for observation.  The fibres are back illuminated by red LEDs.

2dF field plate and robot
The 2dF robot fibre positioner in action.


6dF Observations

The brighter portion of the survey (the 6dF QSO Redshift Survey; 6QZ) was carried out at the UK Schmidt Telescope using the 6-degree Field multi-object spectrographic system.  Up to 150 spectra can be obtained at once over a 6 degree diameter field of view.

6dF Robot
The 6dF robot positioning fibres.

6dF Robot close-up
A closer view of the 6dF system.

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The 2QZ team (July 2003)