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_J, r) objects with 18.25 < b_J < 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_J < 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_J < 20.85) and high QSO surface densities (35 QSOs/deg²). 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 deg², 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 .

This table contains the final optical identifications of the medium-depth (~60 ks), contiguous (2 degree²) XMM-Newton survey of the COSMOS field. XMM-Newton has detected ~1800 X-ray sources down to limiting fluxes of ~5 x 10^-16, ~3 x 10^-15, and ~7 x 10^-15 erg cm^-2 s^-1 in the 0.5-2 keV, 2-10 keV, and 5-10 keV bands, respectively (~1 x 10^-15, ~6 x 10^-15, and ~1 x 10^-14 erg cm^-2 s^-1, in the three bands, respectively, over 50% of the area). The work is complemented by an extensive collection of multi-wavelength data from 24 microns to UV, available from the COSMOS survey, for each of the X-ray sources, including spectroscopic redshifts for >~50% of the sample, and high-quality photometric redshifts for the rest. The XMM-Newton and multi-wavelength flux limits are well matched: 1760 (98%) of the X-ray sources have optical counterparts, 1711 (~95%) have IRAC counterparts, and 1394 (~78%) have MIPS 24 um detections. Thanks to the redshift completeness (almost 100%) the authors were able to constrain the high-luminosity tail of the X-ray luminosity function confirming that the peak of the number density of log L_X > 44.5 active galactic nuclei (AGNs) is at z ~ 2. Spectroscopically identified obscured and unobscured AGNs, as well as normal and star-forming galaxies, present well-defined optical and infrared properties. The authors devised a robust method to identify a sample of ~150 high-redshift (z > 1), obscured AGN candidates for which optical spectroscopy is not available. They were able to determine that the fraction of the obscured AGN population at the highest (L_X > 10⁴⁴ erg s^-1) X-ray luminosity is ~15%-30% when selection effects are taken into account, providing an important observational constraint for X-ray background synthesis. The authors studied in detail the optical spectrum and the overall spectral energy distribution of a prototypical Type 2 QSO (source number 2028), caught in a stage transitioning from being starburst dominated to AGN dominated, which was possible to isolate only thanks to the combination of X-ray and infrared observations. This table was created by the HEASARC in July 2010 based on the electronic version of Table 2 from the paper which was obtained from the Astrophysical Journal web site.

The HEASARC has made some changes to this material in order to make it more compliant with CDS/IAU Nomenclature and HEASARC table standards:

(i) The original naming convention suggested by the authors used a prefix of 'XMMC_' and the J2000.0 RA and Dec position in decimal degrees to 10^-5 degrees precision, e.g., XMMC_150.10515+1.98082'; the HEASARC has replaced these names by alternative new ones (in the alt_name parameter) of the form 'XMMU JHHMMSS.s+DDMMSS' where the prefix is the usual one for XMM-Newton sources and the remainder of the field is the J2000.0 equatorial coordinates truncated to 0.1 seconds of time in RA and to 1 arcsecond in Declination;

(ii) We have used for the alt_name parameter the naming convention recommended by the Dictionary of Nomenclature of Celestial Objects for XMM-COSMOS sources, viz. the "XMMC' prefix and the source (XID) number, e.g., "XMMC 2028'. This is a service provided by NASA HEASARC .

This table contains a source catalog based on XMM-Newton observations of the bright Local Group spiral galaxy M 31. In an analysis of XMM archival observations of M 31, the authors studied the population of X-ray sources (X-ray binaries, supernova remnants) down to a 0.2-4.5 keV luminosity of 4.4 x 10³⁴ erg/s. EPIC hardness ratios and optical and radio information were used to distinguish between different source classes. The survey detected 856 sources in an area of 1.24 square degrees. The authors correlated their sources with earlier M 31 X-ray catalogs and used information from optical, infra-red and radio wavelengths. As sources within M 31, they detected 21 supernova remnants (SNR) and 23 SNR candidates, 18 supersoft source (SSS) candidates, 7 X-ray binaries (XRBs) and 9 XRB candidates, as well as 27 globular cluster sources (GlC) and 10 GlC candidates, which most likely are low mass XRBs within the GlC. Comparison to earlier X-ray surveys revealed transients not detected with XMM-Newton, which add to the number of M 31 XRBs. There are 567 sources classified as hard, which might either be XRBs or Crab-like SNRs in M 31 or background AGN. The number of 44 SNRs and candidates more than doubles the X-ray-detected SNRs. 22 sources are new SNR candidates in M 31 based on X-ray selection criteria. Another SNR candidate might be the first plerion detected outside the Galaxy and the Magellanic Clouds. On the other hand, six sources are foreground stars and 90 are foreground star candidates, one is a BL Lac-type active galactic nucleus (AGN) and 36 are AGN candidates, one source coincides with the Local Group galaxy M 32, one with a background galaxy cluster (GCl) and another is a GCl candidate, all sources which are not connected with M31. In a second paper, the authors presented an extension to the original 2005 XMM-Newton X-ray source catalog of M 31 which contained 39 newly found sources. These sources have been added to the original 856 sources to make a combined catalog of 895 X-ray sources which is contained herein. This table was originally created by the HEASARC in May 2005 based on the CDS table J/A+A/434/483/ file table2.dat (sources numbered 1 to 856). It was updated by the HEASARC in June 2008 by adding the 39 sources from the CDS table J/A+A/480/599/ file table3.dat (sources numbered 857 to 895). This is a service provided by NASA HEASARC .

In their paper, the authors release accurate photometric redshifts for 1692 counterparts to Chandra sources in the central square degree of the Cosmic Evolution Survey (COSMOS) field. The availability of a large training set of spectroscopic redshifts that extends to faint magnitudes enabled photometric redshifts comparable to the highest quality results presently available for normal galaxies. The authors demonstrate that morphologically extended, faint X-ray sources without optical variability are more accurately described by a library of normal galaxies (corrected for emission lines) than by active galactic nucleus (AGN) dominated templates, even if these sources have AGNlike X-ray luminosities. Preselecting the library on the bases of the source properties allowed them to reach an accuracy sigma[Delta-z/(1+Z_spec)] ~ 0.015 with a fraction of outliers of 5.8% for the entire Chandra-COSMOS sample. These Chandra sources are not contained in this table but are available in the HEASARC table CCOSMPHOTZ). In addition, in this study the authors released revised photometric redshifts for the 1735 optical counterparts of the XMM-detected sources over the entire 2 deg² of COSMOS, and these are the sources listed in the present table. For 248 sources, their updated photometric redshift differs from the previous release by Delta-z > 0.2. These changes are predominantly due to the inclusion of newly available deep H-band^ photometry (H_AB = 24 mag). The authors illustrate once again the importance of a spectroscopic training sample and how an assumption about the nature of a source together, with the number and the depth of the available bands, influences the accuracy of the photometric redshifts determined for AGN. These considerations should be kept in mind when defining the observational strategies of upcoming large surveys targeting AGNs, such as eROSITA at X-ray energies and the Australian Square Kilometre Array Pathfinder Evolutionary Map of the Universe in the radio band. This table contains the photometric redshifts and related quantities for 1735 XMM-Newton sources over the entire 2 square degrees of the COSMOS field. Notice that in the original as-published paper no positional information was provided. The HEASARC has assumed that the source numbers used in the present catalog are in the same source numbering scheme as used by Cappelluti et al. (2009, A&A, 497, 635, the XMM-Newton Wide-Field Survey in the COSMOS Field Point-like X-ray Source Catalog, available at the HEASARC as the XMMCOSMOS table) and thus obtained the positions and (position-based) names corresponding to these X-ray sources from the latter. This table was created by the HEASARC in November 2011 based on an electronic version of Table 5 from the reference paper which was obtained from the ApJ website. This is a service provided by NASA HEASARC .