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ROS13HRCXO - ROSAT/XMM-Newton 13-hour Field Chandra X-Ray Source Catalog

HEASARC
Archive

Overview

This table contains some of the results from a Chandra ACIS-I survey of a high-latitude region at RA, Dec = 13 hours, +38 degrees which was earlier observed with ROSAT and which had recently been observed by XMM-Newton for 200 ks. XMM-Newton was expected to provide good-quality X-ray spectra for over 200 sources with fluxes around the knee of the log N /log S distribution, which are responsible for the bulk of the X-ray background. The main aim of the Chandra observations was to provide arcsecond, or better, positions, and hence reliable identifications, for the XMM-Newton sources. The ACIS-I observations were arranged in a mosaic of four 30-ks pointings, covering almost all of the 15-arcminute radius XMM-Newton/ROSAT field. 214 Chandra sources were detected above a Cash likelihood statistic of 25, which approximates to a 5-sigma significance, to a limiting flux of ~ 1.3 x 10-15erg/cm2/s (0.5 - 7 keV). Optical counterparts were derived from a Subaru SuprimeCam image reaching to R ~ 27. The very large majority of the Chandra sources have an optical counterpart, with the distribution peaking at 23 < R < 24, although 14 have no counterpart to R = 27. The fraction of X-ray sources with no identification brighter than R = 27 is similar to that found in deeper Chandra surveys.

The majority of the identifications are with galaxies. As found in other Chandra surveys, there is a very wide range of optical magnitudes for a given X-ray flux, implying a range of emission mechanisms, and many sources have high LX/Lopt ratios, implying absorption at moderate redshift. Comparison with the earlier ROSAT survey shows that the accuracy of the ROSAT positions agrees very well with the predictions from simulations by McHardy et al. and that the large majority of the identifications were correct.


Catalog Bibcode

2003MNRAS.342..802M

References

A medium-deep Chandra and Subaru survey of the 13-h XMM/ROSAT deep survey area.
    McHardy I.M., Gunn K.F., Newsam A.M., Mason K.O., Page M.J., Takata T.,
    Sekiguchi K., Sasseen T., Cordova F., Jones L.R., Loaring N.
   <Mon. Not. R. Astron. Soc. 342, 802 (2003)>
   =2003MNRAS.342..802M

Provenance

This table was created by the HEASARC in July 2013 based on CDS Catalog J/MNRAS/342/802 files table2.dat and table5.dat.

Parameters

Source_Number
A unique identification number for each Chandra X-ray source in the catalog, in order of decreasing Chandra X-ray flux.

Name
The designation of the Chandra X-ray source, using the prefix '[MGN2003]' (for McHardy, Gunn, Newsam 2003) and the Chandra source number for these names, in accordance with the naming convention recommended by the Dictionary of Nomenclature of Celestial Objects.

Source_Flag
This flag parameter contains codes for individual notes on the source, as follows:

        a = Optical position is taken direct from the APM scan of the POSS-II
            plates and magnitude is from UH imaging.
        c = Magnitude taken from CFHT image. For source 114 we give the
            coordinates of a very faint object which is not visible on the
            CFHT image but which is visible on a deep B-band image (Croom,
            private communication). Sources 99 and 114, the identifications
            of which are unreliable because of the lower-sensitivity
            imaging, are not included in any statistical analysis.
        o = Optical counterpart is not deblended properly by SExtractor
            software so the coordinates and magnitude, but not stellarity or
            FWHM, are calculated manually.
  

Alt_Cand_Flag
This flag parameter has non-blank values to indicate that there are alternative optical candidates for the X-ray source than the one listed in this table:

         U = the true identification is uncertain.
         P = the primary identification is probably correct but SExtractor
             did pick up another, less likely, candidate within 2 arcsec of
             the Chandra centroid. The primary candidate is chosen, unless
             stated otherwise, on the basis of being closer to the Chandra
             centroid and being brighter.
  
Information about these alternative counterparts is given in Table A1 and Appendix A of the reference paper.

Flux
The broad-band 0.5 - 7.0 keV flux of the Chandra X-ray source, in erg/s/cm2. Fluxes are determined from the maximum likelihood (ML) parameters of the Cash statistic, where count rate is a free parameter. These count rates automatically compensate for the variation in the point-spread function (PSF) and the complicate exposure map of the observations. The ML count rates are then converted to these X-ray fluxes by assuming a power-law spectrum with an energy spectral index of 0.4 and a Galactic absorption of 6.5 x 1019 cm-2.

Cash_Chi_Squared
The Cash chi-squared likelihood statistic C for the Chandra X-ray source. The threshold for detection of C = 25 approximates to 5 sigma.

RA
The Right Ascension of the centroid of the Chandra X-ray source in the selected equinox. This was given in J2000 equatorial coordinates and to a precision of 0.01 seconds of time in the original source table.

Dec
The Declination of the of the centroid Chandra X-ray source in the selected equinox. This was given in J2000 equatorial coordinates and to a precision of 0.01 arcseconds in the original source table.

LII
The Galactic Longitude of the Chandra X-ray source centroid.

BII
The Galactic Latitude of the Chandra X-ray source centroid.

Opt_CXO_Offset_RA
The optical-Chandra positional offset (in that sense) in the Right Ascension direction for the primary optical identification listed here, in arcseconds.

Opt_CXO_Offset_Dec
The optical-Chandra positional offset (in that sense) in the Declination direction for the primary optical identification listed here, in arcseconds.

Opt_CXO_Offset
The total optical-Chandra positional offset for the primary optical identification listed here, in arcseconds.

Rmag_Limit
This parameter is a limit flag for the R-magnitude of the optical counterpart, either '>' or ">='.

Rmag
The R-band magnitude of the optical counterpart of the Chandra X-ray source.

CXO_Off_Axis
The off-axis angle of the Chandra X-ray source, in arcminutes.

Rosxmm_Off_Axis
The off-axis angle of the X-ray source in the ROSAT and XMM-Newton observations, in arcminutes.

Opt_FWHM
The full width at half maximum (FWHM) of the optical counterpart to the Chandra X-ray source, in arcseconds.

Opt_Stellarity
The stellarity of the optical counterpart to the Chandra X-ray source, where values closer to 0.00 imply extended, e.g., a galaxy, and values closer to 1.00 imply point-like, e.g., a star.

ROSAT_Source_Number
The corresponding ROSAT source number for the X-ray source as given in McHardy et al. (1998, MNRAS, 295, 641).

ROSAT_RA
The Right Ascension of the corresponding ROSAT source in the selected equinox as given in McHardy et al. (1998, MNRAS, 295, 641).

ROSAT_Dec
The Declination of the corresponding ROSAT source in the selected equinox as given in McHardy et al. (1998, MNRAS, 295, 641).

ROSAT_CXO_Offset
The total offset between the ROSAT and Chandra X-ray source positions, in arcseconds.

Rosopt_CXO_Offset
The total offset between the proposed ROSAT optical counterpart given in McHardy et al. (1998, MNRAS, 295, 641) and the Chandra X-ray source positions, in arcseconds.

Rosopt_Broad_Type
The classification of the proposed ROSAT optical counterpart given in McHardy et al. (1998, MNRAS, 295, 641), coded as follows:

        BLANK  = no classification
        CLU    = cluster
        G/NELG = Galaxy/narrow-emission-line galaxies
        G/QSO? = Galaxy/quasar ?
        GAL?   = Galaxy ?
        GP/GAL = Galaxy pair/galaxy
        GRP    = Group of galaxies
        GSTAR  = G star
        KSTAR? = K star ?
        MSTAR  = M star
        NELG   = narrow-emission-line galaxies
        QSO    = quasar
  

Rosopt_Redshift
The redshift of the proposed ROSAT optical counterpart as given in McHardy et al. (1998, MNRAS, 295, 641)

Rosopt_Confidence
The parameter indicating the confidence in the classification of the proposed ROSAT optical counterpart, as given in McHardy et al, (1998, MNRAS, 295, 641), coded as follows:

            C = certain (code was '*' in McHardy et al 1998)
            L = likely  (code was '(*)' in McHardy et al 1998)
            P = possible (code was ' ' in McHardy et al 1998)
  

Rosopt_Confirmed_Flag
This flag parameter indicates whether or not the optical counterpart to the ROSAT X-ray source proposed in McHardy et al. (1998, MNRAS, 295, 641) has been confirmed, as follows:

        Y = optical counterpart is < 1" from the Chandra source when the Chandra
            off-axis angle OffC is < 6' (extended to < 1.6" for 6 < OffC < 8')
        N = optical counterpart is > 3" from the Chandra source
        ? = all intermediate cases
  

Contact Person

Questions regarding the ROS13HRCXO database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 31-Jul-2013