J/ApJS/149/29 ROSAT North Ecliptic Pole Survey (Gioia+, 2003)
The ROSAT North Ecliptic Pole Survey: the optical identifications. Gioia I.M., Henry J.P., Mullis C.R., Bohringer H., Briel U.G., Voges W., Huchra J.P. <Astrophys. J. Suppl. Ser. 149, 29 (2003)> =2003ApJS..149...29G
ADC_Keywords: Surveys ; Radio sources ; Redshifts ; Cross identifications Keywords: BL Lacertae objects: general- catalogs - galaxies: clusters: general - surveys - X-rays: general - X-rays: stars Abstract: The X-ray data around the North Ecliptic Pole (NEP) of the ROSAT All Sky Survey have been used to construct a contiguous area survey consisting of a sample of 445 individual X-ray sources above a flux of ∼2x10-14erg/cm2/s in the 0.5-2.0keV energy band. The NEP survey is centered at RA=18:00 (2000) DE=+66:33 and covers a region of 80.7deg2 at a moderate Galactic latitude of b=29.8°. Hence, the NEP survey is as deep and covers a comparable solid angle to the ROSAT serendipitous surveys but is also contiguous. We have identified 99.6% of the sources and determined redshifts for the extragalactic objects. In this paper we present the optical identifications of the NEP catalog of X-ray sources including basic X-ray data and properties of the sources. We also describe with some detail the optical identification procedure. The classification of the optical counterparts to the NEP sources is very similar to that of previous surveys, in particular the Einstein Extended Medium Sensitivity Survey (EMSS). The main constituents of the catalog are active galactic nuclei (AGNs) (∼49%), either type 1 or type 2 according to the broadness of their permitted emission lines. Stellar counterparts are the second most common identification class (∼34%). Clusters and groups of galaxies comprise 14%, and BL Lacertae objects 2%. One non-AGN galaxy and one planetary nebula have also been found. The NEP catalog of X-ray sources is a homogeneous sample of astronomical objects featuring complete optical identification. Description: The NEP region was observed many times by the ROSAT satellite since the RASS scan pattern overlapped at the ecliptic poles. While the mean RASS exposure time across the entire sky is approximately 400s, the NEP region exposure time approaches 40ks at the pole. The minimum, median, and maximum exposure times in the NEP survey regions are 1.7, 4.8, and 38ks, respectively. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table3.dat 130 446 ROSAT NEP Source Catalog notes.dat 80 346 Individual notes
See also: IX/29 : ROSAT All-Sky Survey Faint Source Catalog (Voges+ 2000) J/A+AS/141/257 : Very deep IRAS 60um sources in NEP region (Aussel+, 2000) J/A+AS/134/221 : Radio-loud ROSAT sources near NEP (Brinkmann+, 1999) J/ApJS/93/145 : Radio survey around North Ecliptic Pole (Kollgaard+, 1994) J/A+AS/75/67 : Survey around the North Ecliptic Pole at 11cm (Loiseau+, 1988) J/ApJS/162/304 : ROSAT NEP X-ray source catalog (Henry+, 2006) Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 2 A2 --- --- [RX] 4- 15 A12 --- RX Object name (JHHMM.m+DDMM) 17- 20 I4 --- NEP North Ecliptic Pole scan number 22- 23 I2 h RAh Hour of ROSAT Right Ascension (J2000) 25- 26 I2 min RAm Minute of ROSAT Right Ascension (J2000) 28- 31 F4.1 s RAs Second of ROSAT Right Ascension (J2000) 33 A1 --- DE- Sign of the ROSAT Declination (J2000) 34- 35 I2 deg DEd Degree of ROSAT Declination (J2000) 37- 38 I2 arcmin DEm Arcminute of ROSAT Declination (J2000) 40- 41 I2 arcsec DEs Arcsecond of ROSAT Declination (J2000) 43- 44 I2 h RAOh ? Hour of associated optical object Right Ascension (J2000) 46- 47 I2 min RAOm ? Minute of associated optical object Right Ascension (J2000) 49- 52 F4.1 s RAOs ? Second of associated optical object Right Ascension (J2000) 54 A1 --- DEO- Sign of the associated optical object Declination (J2000) 55- 56 I2 deg DEOd ? Degree of associated optical object Declination (J2000) 58- 59 I2 arcmin DEOm ? Arcminute of associated optical object Declination (J2000) 61- 62 I2 arcsec DEOs ? Arcsecond of associated optical object Declination (J2000) 64- 67 F4.1 --- S/N Signal to noise (1) 69- 75 F7.2 10-17W/m2 FXdet Rest frame detected 0.5-2keV unabsorbed flux in units of 10-14erg/cm2/s (2) 77- 83 F7.2 10-17W/m2 FXtot Rest frame total 0.5-2 keV unabsorbed flux in units of 10-14erg/cm2/s (3) 85- 91 F7.3 10+37W LX ? Rest frame K-corrected 0.5-2keV luminosity in units of 1044erg/s (4) 93- 98 F6.4 --- z ? Spectroscopically measured redshift (5) 100-109 A10 --- ID Optical identification of X-ray source (6) 110 A1 --- n_RX [n] note detailed in notes.dat file 112-129 A18 --- Notes Additional notes (7)
Note (1): On the detected source count rate determined as net source count rate over 1σ uncertainty on the count rate. Note (2): The detect flux is measured in the photometry circular aperture (5' radius). To determine the fluxes for the different classes of astronomical objects we have converted from count rate to unabsorbed flux using conversion factors based on three different types of source spectra (see Section 2). Note (3): The total flux accounts for the flux outside the photometry aperture and reflects the size correction applied to the detect flux. For point sources this flux correction factor is constant and equal to 1.0369 (see Section 2), while it varies for extended sources, such as clusters or groups of galaxies. The flux correction factor for extended sources is given in Column Notes. Note (4): For extragalactic objects with uncertainties based on the fractional errors on the source count rate. K-correction factors for clusters of galaxies, assuming a Raymond-Smith plasma spectrum with a metallicity 0.3 solar, are 0.76, 0.95 and 1.01, minimum, median and maximum values respectively. For AGN the assumed power law spectrum with energy index =-1 gives a formal K-correction factor of 1. Note (5): Typical uncertainty is ≤0.001. Note (6): Optical identification of X-ray source is classified as follows: AGN = active galactic nucleus, either type 1 (AGN1) or type 2 (AGN2) (see Section 4 of the paper); STAR = star plus spectral type if known; CL = group or cluster of galaxies; BL = BL Lacertae object; GAL = normal galaxy; PN = Planetary Nebula. Note (7): Comments regarding the source, such as size correction factor (sc=sizecorr) for galaxy clusters, or indication of a Note (n) to the source given in Section 6 of the paper.
Byte-by-byte Description of file: notes.dat
Bytes Format Units Label Explanations
1- 2 A2 --- --- [RX] 4- 15 A12 --- RX Object name (JHHMM.m+DDMM) 17- 80 A64 --- Note Text of the note
History: From electronic version of the journal * 31-Mar-2005: in file "notes.dat", the name RX J1736.4+6828 was corrected into RX J1736.4+6820.
(End) Greg Schwarz [AAS], Patricia Bauer [CDS] 17-Nov-2003
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