TWODFQSOZ ivo://nasa.heasarc/twodfqsoz NASA/GSFC HEASARC Croom et al. 2026-07-17 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source The final catalog of the 2dF QSO Redshift Survey (2QZ) is based on Anglo-Australian Telescope 2dF spectroscopic observations of 44,576 color-selected (u, b<sub>J</sub>, r) objects with 18.25 < b<sub>J</sub> < 20.85 selected from automated plate measurement scans of UK Schmidt Telescope (UKST) photographic plates. The 2QZ comprises 23,338 quasi-stellar objects (QSOs), 12,292 galactic stars (including 2,071 white dwarfs) and 4,558 compact narrow emission-line galaxies. The authors obtained a reliable spectroscopic identification for 86 per cent of objects observed with 2dF. They also report on the 6dF QSO Redshift Survey (6QZ), based on UKST 6dF observations of 1,564 brighter (16 < b<sub>J</sub> < 18.25) sources selected from the same photographic input catalog. In total, the authors identified 322 QSOs spectroscopically in the 6QZ. The completed 2QZ is, by more than a factor of 50, the largest homogeneous QSO catalog ever constructed at these faint limits (b<sub>J</sub> < 20.85) and high QSO surface densities (35 QSOs/deg<sup>2</sup>). As such, it represents an important resource in the study of the Universe at moderate-to-high redshifts. The survey area comprised 30 UKST fields, arranged in two 75 degrees by 5 degrees declination strips, one passing across the South Galactic Gap centered on Dec = -30 degrees (the SGP strip), and the other across the North Galactic Gap centered on Dec = 0 degrees (referred to in the reference paper as the equatorial strip, but also known as the NGP strip. The total survey area is 721.6 deg<sup>2</sup>, when allowance is made for regions of sky excised around bright stars. Spectroscopic observations of the input catalogue were made with the 2dF instrument at the Anglo-Australian Telescope (AAT; the 2QZ sample) and the 6dF instrument at the UKST (the 6QZ sample). 2dF spectroscopic observations began in January 1997 and were completed in April 2002. Six-degree Field observations were performed over the period 2001 March-2002 September. This online catalog was created by the HEASARC in October 2010 based on the machine-readable table 2qz.dat obtained from the CDS (their catalog VII/241). This is a service provided by NASA HEASARC . 2004MNRAS.349.1397C https://heasarc.gsfc.nasa.gov/W3Browse/all/twodfqsoz.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=twodfqsoz& GET text/xml 180 99999 true 48.26175 -32.30294444 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=twodfqsoz GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_twodfqsoz&Action=More+Options&Action=Parameter+Search&ConeAdd=1 GALAXY CATALOG 0.0166666666666667 Optical public twodfqsoz 2dF QSO Redshift (2QZ) Survey name Catalog Source Designation (2QZ JHHMMSS.S+DDMMSS) meta.id;meta.main char nullable ra Right Ascension degree pos.eq.ra;meta.main double nullable dec Declination degree pos.eq.dec;meta.main double nullable bj_mag b_J Magnitude mag phot.mag;em.opt.B double nullable redshift_1 Redshift from First Spectrum src.redshift double nullable quality_flag_1 Quality Flag for First Spectrum meta.code.qual;src.redshift short nullable broad_type_1 Identification for First Spectrum src.class char nullable redshift_2 Redshift from Second Spectrum src.redshift double nullable quality_flag_2 Quality Flag for Second Spectrum meta.code.qual;src.redshift short nullable broad_type_2 Identification for Second Spectrum src.class char nullable rass_flux Flux at 0.1-2.4keV from RASS erg/s/cm^2 phot.flux;em.X-ray.soft double nullable lii Galactic Longitude degree pos.galactic.lon double nullable apm_x_pos APM Scan X Position (1 pixel = 8 um) pixel pos.cartesian.x;instr.det double nullable u_bj_color u-b_J Color Index mag phot.color;em.opt.U;em.opt.B double nullable apm_y_pos APM Scan Y Position (1 pixel = 8 um) pixel pos.cartesian.y;instr.det double nullable num_obs Number of Observations short nullable comment_spectrum_1 Specific Comment on Observation 1 meta.note char nullable field_spect_number_1 Field and Spectrograph for First Spectrum meta.id;obs.field;instr.det short nullable comment_spectrum_2 Specific Comment on Observation 2 meta.note char nullable spectrum_1_date Date of Observation for First Spectrum mjd time.epoch int nullable class Browse Object Classification src.class short nullable reddening Reddening E(B-V) from Schegel et al., 1998ApJ...500..525S mag phot.color.excess double nullable sector_name Designation of the Sector This Object Inhabits meta.id;obs.field char nullable source_number Sequential Identification Number for Each Source in Catalog meta.id;src int nullable bii Galactic Latitude degree pos.galactic.lat double nullable field_spect_number_2 Field and Spectrograph for Second Spectrum meta.id;obs.field;instr.det short nullable snr_spectrum_1 Signal-to-Noise Ratio for First Spectrum stat.snr double nullable bj_r_color b_J-r Color Index mag phot.color;em.opt.B;em.opt.R double nullable fiber_number_2 2dF Fiber Number for Second Observation meta.id;instr.det short nullable spectrum_2_date Date of Observation for Second Spectrum mjd time.epoch int nullable previous_redshift Redshift If Previously Known src.redshift double nullable snr_spectrum_2 Signal-to-Noise Ratio for Second Spectrum stat.snr double nullable fiber_number_1 2dF Fiber Number for First Observation meta.id;instr.det short nullable ukst_field_number UKST Survey Field Number meta.id;obs.field short nullable internal_name Internal Designation of the Object meta.id;src char nullable flux_20_cm Flux Density at 1.4GHz from NVSS mJy phot.flux.density;em.radio.750-1500MHz short nullable "__x_ra_dec" System unit vector column double nullable "__y_ra_dec" System unit vector column double nullable "__z_ra_dec" System unit vector column double nullable "__row" System index column char nullable