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 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:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 130 446 ROSAT NEP Source Catalog
notes.dat 80 346 Individual notes
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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
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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)
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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.
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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
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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