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The authors of this catalog have developed the SIX statistic to identify bright, highly likely active galactic nucleus (AGN) candidates solely on the basis of Wide-field Infrared Survey Explorer (WISE), Two-Micron All-Sky Survey (2MASS), and ROSAT All-Sky Survey (RASS) data. This statistic was optimized with data from the preliminary WISE survey and the Sloan Digital Sky Survey, and tested with Lick 3 m Kast spectroscopy. The authors find that sources with SIX < 0 have a >~ 95% likelihood of being an AGN (defined in this paper as a Seyfert 1, quasar, or blazar). This statistic was then applied to the full WISE/2MASS/RASS dataset, including the final WISE data release, to yield the "W2R" sample of 4316 sources with SIX < 0. Only 2209 of these sources are currently in the Veron-Cetty and Veron (VCV) Catalog of spectroscopically confirmed AGNs, indicating that the W2R sample contains nearly 2000 new, relatively bright (J <~ 16) AGNs. The authors utilize the W2R sample to quantify biases and incompleteness in the VCV Catalog. They find that it is highly complete for bright (J < 14), northern AGNs, but the completeness drops below 50% for fainter, southern samples and for sources near the Galactic plane. This approach also led to the spectroscopic identification of 10 new AGNs in the Kepler field, more than doubling the number of AGNs being monitored by Kepler. The W2R sample contains better than 1 bright AGN every 10 deg2, permitting construction of AGN samples in any sufficiently large region of sky. This table contains the 4316 sources comprising the W2R sample.

Catalog Bibcode

2012ApJ...751.. 52E


Reliable Identifications of Active Galactic Nuclei from the WISE, 2MASS, and
ROSAT All-Sky Surveys
    Edelson, R.; Malkan, M.
   <Astrophysical Journal, Volume 751, Issue 1, article id. 52 (2012)>


This table was created by the HEASARC in June 2012 based on an electronic version of Table 3 from the reference paper which was obtained from the ApJ website.


A running sequential identification number for each source in the catalog in order of increasing value of the SIX parameter.

The unique 2MASS source identifier (Cntr).

The Right Ascension of the 2MASS source in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.01 seconds of time.

The Declination of the 2MASS source in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.1 aecseconds.

The Galactic Longitude of the 2MASS source.

The Galactic Latitude of the 2MASS source.

The 2MASS J Band Magnitude of the source.

The SIX figure of merit parameterization for the source, where SIX = log10 (SI + 0.116* SX), where S_I is the infrared color discriminator (1.7 * c2 + 2.0 * c3 + c4) and SX is the discriminator based on the distance d between the WISE and RASS source positions (d/e)2. The construction of S_IX is discussed in Section 2 of the reference paper.

The infrared color discriminator SI = 1.7 * c2 + 2.0 * c3 + c4, where the weights c2, c3 and c4 are defined by equations (2), (3) and (1) of the reference paper. See Section 2 of the reference paper for more details.

The logarithm of SX, the discriminator based on the distance d between the WISE and RASS source positions in multiples of the RASS positional uncertainty e, viz. SX = (d/e)2.

The RASS source name.

The VCV Catalog identifier of the source.

The AGN type as listed in the VCV Catalog.

The AGN redshift as listed in the VCV Catalog.

This flag parameter has possible non-blank values of:

      1 = previously unidentified,i.e., not listed in the VCV Catalog;
      2 = the source listed in the VCV Catalog does not fit this paper's
          definition of an AGN.

The HEASARC Browse object classification of the object, based on the veron_object_type parameter value. Note that the HEASARC has set all sources lacking a VCV object type to the generic AGN class, based on the authors' estimate that >~ 95% of sources in this table are AGN. This of course implies that <~ 5% (<~ 216 sources) are not AGN.

Contact Person

Questions regarding the W2RAGNCAT database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 4-Jun-2012