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ROSNEPAGN - ROSAT North Ecliptic Pole Survey Active Galactic Nuclei Catalog



The ROSAT North Ecliptic Pole (NEP) Survey of Active Galactic Nuclei (AGN) Catalog is an X-ray flux-limited sample of 219 AGN discovered in the contiguous 80.7 square degrees region of the ROSAT North Ecliptic Pole (NEP) Survey (Gioia et al. 2003, ApJS, 149, 29; CDS Cat. <J/ApJS/149/29>). This catalog features complete optical identifications and spectroscopic redshifts. The median redshift, X-ray flux, and X-ray luminosity are z = 0.41, fx = 1.1 x 10^-13 erg/cm^2/s, and Lx = 9.2 x 10^43 h70^-2 erg/s (0.5 - 2.0 keV), respectively. Unobscured Type 1 AGN are the dominant constituents (90%) of this soft X-ray-selected sample of AGN.

This catalog sample includes several notable revisions relative to previous versions of the catalog (Mullis 2001, Ph. D. thesis, U. Hawaii; Gioia et al. 2003, ApJS, 149, 29, available in HEASARC Browse as the ROSNEPOID table). Firstly, the AGN fluxes and luminosities previously reported were overestimated by approximately 20% on average as a result of an error in the conversion of X-ray count rate to flux. Secondly, the sample has grown by 1 because of the reclassification of one of the X-ray sources (RX J1824.7+6509). Finally, in the present study the authors have adopted the presently favored "concordance" cosmology in computing the X-ray luminosities. The revised and updated catalog with corrected properties presented here should be the reference point for any future work with the ROSAT NEP AGN sample.

Catalog Bibcode



Spatial correlation function of X-ray-selected active galactic nuclei.
    Mullis C.R., Henry J.P., Gioia I.M., Bohringer H., Briel U.G., Voges W.,
    Huchra J.P.
   <Astrophys. J., 617, 192-208 (2004)>


This table was created by the HEASARC in August 2005 based on CDS table J/ApJ/617/192/table1.dat.


The source name as given in the published paper, formed using the prefix 'RX J' (for ROSAT X-ray source, Julian 2000 position), and the X-ray centroid position truncated to 0.1 minutes of time in RA and 1 arcmin in Declination.

This parameter is a flag which is set to 'a' for the source 'RX J1824.7+6509' (NEP 5500), which was formerly classified as a stellar X-ray source based on the literature. However, more recent work has convincingly demonstrated that this source is a type 1 AGN at a redshift z = 0.303 (e.g., Engels et al. 1998, A&AS, 128, 507 = CDS Cat. <J/A+AS/128/507>).

The ROSAT NEP internal catalog identification number.

The Right Ascension, in fixed J2000 sexagesimal format, of the X-ray centroid.

The Declination, in fixed J2000 sexagesimal format, of the X-ray centroid.

The Right Ascension of the associated optical object in the selected equinox. This was given in J2000 coordinates and to a precision of 0.1 seconds of time in the original catalog.

The Declination of the associated optical object in the selected equinox. This was given in J2000 coordinates and to a precision of 1 arcsecond in the original catalog.

The Galactic Longitude of the associated optical object.

The Galactic Latitude of the associated optical object.

The column density of Galactic hydrogen, in atoms cm^-2, from Elvis et al. (1994, ApJS, 95, 413), with supplements from Stark et al. (1992, ApJS, 79, 77).

The count rate in the 0.1 - 2.4 keV energy band, in counts per second (ct/s), measured within a circular photometric aperture of 5 arcminutes radius.

The 1-sigma uncertainty in the count rate in the 0.1 - 2.4 keV energy band, in ct/s, based on a maximum-likelihood analysis.

The unabsorbed flux in the 0.5 - 2.0 keV energy band, in erg/s/cm^2. The authors have derived the flux from the count rate assuming that the source has a power-law spectrum with a photon index Gamma of 2, and with absorption fixed at the Galactic value for the source position. This total flux accounts for the small fraction of point source flux falling outside the photometry aperture and reflects the size correction applied to the detect flux. For point sources such as AGN, this flux correction factor is constant and equal to 1.0369.

The rest-frame, K-Corrected 0.5 - 2.0 keV luminosity, in erg/s. Note that the K-correction for a power-law spectrum is (1+z)^(Gamma-2), and is thus unity for Gamma = 2 (adopted cosmology: H_0 =70 h70 km/s/Mpc, Omega_M = 0.3, and Omega_Lambda = 0.7).

The spectroscopically measured redshift (typical uncertainty < 0.001).

The AGN classification based on the equivalent width of the emission lines and the broadness of the permitted lines (1 = type 1, 2 = Type 2).

Contact Person

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

Page Author: Browse Software Development Team
Last Modified: 7-Sep-2005