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CDFN2MSNEW - Chandra Deep Field North 2-Megasecond Improved Point Source Catalog

HEASARC
Archive

Overview

This table contains the improved point-source catalog for the 2-Ms Chandra Deep Field-North (CDF-N) Survey, implementing a number of recent improvements in Chandra source-cataloguing methodology. For the CDF-N, the main catalog (entries from which are indicated with parameter values of source_sample = "Main" in this HEASARC representation) contains 683 X-ray sources detected with wavdetect at a false-positive probability threshold of 10-5 that also satisfy a binomial-probability source-selection criterion of P <= 0.004. Such an approach maximizes the number of reliable sources detected: a total of 196 main-catalog sources are new compared to the Alexander et al. (2003, AJ, 126, 539) CDF-N main catalog. The authors also provide a CDF-N supplementary catalog that consist of 72 sources (entries from which are indicated with parameter values of source_sample = "Supp" in this HEASARC representation) detected at the same wavdetect threshold and having P of 0.004-0.1 and Ks <= 22.9 mag counterparts. For all 755 CDF-N sources, including the 234 newly detected ones (these being generally fainter and more obscured), the authors determine X-ray source positions utilizing centroid and matched-filter techniques; they also provide multi-wavelength identifications, apparent magnitudes of counterparts, spectroscopic and/or photometric redshifts, basic source classifications, and estimates of observed active galactic nucleus and galaxy source densities around respective field centers. Simulations show that the CDF-N main catalog is highly reliable and reasonably complete. Background and sensitivity analyses indicate that the on-axis mean flux limits reached represent a factor of ~1.5-2.0 improvement over the previous CDF-N limit.

The 2 Ms CDF-N consists of a total of 20 separate Chandra observations taken between 1999 November 13 and 2002 February 22 with ACIS (see Alexander et al., 2003, AJ, 126, 539 for more details).


Catalog Bibcode

2016ApJS..224...15X

References

The 2 Ms Chandra Deep Field-North survey and the 250 Ks Extended Chandra Deep
Field-South survey: improved point-source catalogs.
    Xue Y.Q., Luo B., Brandt W.N., Alexander D.M., Bauer F.E., Lehmer B.D.,
    Yang G.
   <Astrophys. J. Suppl. Ser., 224, 15-15 (2016)>
   =2016ApJS..224...15X    (SIMBAD/NED BibCode)

Provenance

This table was created by the HEASARC in August 2016 based on CDS Catalog J/ApJS/224/15 files table3.dat (the main source catalog) and table6.dat (the supplementary source catalog).

Parameters

Source_Sample
This HEASARC-created field indicates from which sample the entry was taken: "Main" if it comes from the main catalog (Table 3 in the published paper) of 683 X-ray sources or "Supp" if it comes from the supplementary catalog (Table 6 in the published paper).

Source_Number
A sequential identification number for each source in the specified sample, "Main" or "Supp", in order of increasing J2000.0 RA. Thus, to uniquely specify a source both the source_sample and source_number values must be specified.

Name
The standard source designation in the style recommended by the Dictionary of Nomenclature of Celestial Objects for unregistered Chandra X-ray source, which was created by the HEASARC using the prefix 'CXOU' and the J2000.0 Right Ascension and Declination truncated to 0.1 seconds of time in RA and to 1 arcsecond in Declination.

RA
The Right Ascension of the best-fit X-ray source in the selected equinox. This was given in J2000.0 sexagesimal coordinates to a precision of 0.01 seconds of time in the original table.

Dec
The Declination of the best-fit X-ray source in the selected equinox. This was given in J2000.0 sexagesimal coordinates to a precision of 0.1 arcseconds in the original table.

LII
The Galactic Longitude of the best-fit X-ray source.

BII
The Galactic Latitude of the best-fit X-ray source.

Log_Prob_No_Src
The minimum value of log P among the three standard bands, where P is the binomial no-source probability as calculated by AE. More negative values of log P correspond to a source detection of higher significance. For sources with P = 0, the HEASARC has set log P = null (rather than -99.0 as in the original version). The authors find a median value of log P = -10.7 for the main-catalog sources, being much smaller than the main-catalog selection threshold value of log P < -2.4 (i.e., P < 0.004; see Section 2.3.1 of the reference paper).

Log_Prob_False_Pos
The logarithm of the minimum WAVDETECT false-positive probability detection threshold. The authors find that 464, 43, 65, and 111 of the main-catalog sources have minimum WAVDETECT probabilities of 10-8, 10-7, 10-6, and 10-5, respectively (see Figure 6 of reference paper).

Error_Radius
The X-ray positional uncertainty in units of arcseconds at the ~68% confidence level, which is computed utilizing Equation (2) in the reference paper, which is dependent on both the off-axis angle and the aperture-corrected net source counts. For the main-catalog sources, the positional uncertainty ranges from 0.10 to 2.2 arcseconds, with a median value of 0.47 arcseconds.

Off_Axis
The off-axis angle of each X-ray source, in units of arcminutes, that is the angular separation between the X-ray source and the average aim point given in Section 2.1.1 of the reference paper. For the main-catalog sources, the off-axis angle ranges from 0.13 to 14.63 arcminutes, with a median value of 6.01 arcminutes (see Section 2.1.1 for the observational pointing scheme and roll constraints that led to such a wide range of off-axis angles).

FB_Counts_Limit
This parameter is set to '<' if the source was not considered to be detected in the corresponding energy band, else is left blank.

FB_Counts
The aperture-corrected net (i.e., background-subtracted) source counts (or upper limit) for the standard full (0.5 - 7.0 keV) band (computed in Section 2.2.2 of the reference paper). The authors treat a source as being "detected" for photometry purposes in a given band only if it satisfies P < 0.004 in that band. They calculate upper limits for sources not detected in a given band, according to the Bayesian method of Kraft et al. (1991, ApJ, 374, 344) for a 90% confidence level, and set the corresponding errors to null.

FB_Counts_Pos_Err
The 1-sigma upper statistical error (Gehrels 1986, ApJ, 303, 336) in the aperture-corrected net (i.e., background-subtracted) source counts in the specified band.

FB_Counts_Neg_Err
The 1-sigma lower statistical error (Gehrels 1986, ApJ, 303, 336) in the aperture-corrected net (i.e., background-subtracted) source counts in the specified band.

SB_Counts_Limit
This parameter is set to '<' if the source was not considered to be detected in the corresponding energy band, else is left blank.

SB_Counts
The aperture-corrected net (i.e., background-subtracted) source counts (or upper limit) for the standard soft (0.5 - 2.0 keV) band (computed in Section 2.2.2 of the reference paper). The authors treat a source as being "detected" for photometry purposes in a given band only if it satisfies P < 0.004 in that band. They calculate upper limits for sources not detected in a given band, according to the Bayesian method of Kraft et al. (1991, ApJ, 374, 344) for a 90% confidence level, and set the corresponding errors to null.

SB_Counts_Pos_Err
The 1-sigma upper statistical error (Gehrels 1986, ApJ, 303, 336) in the aperture-corrected net (i.e., background-subtracted) source counts in the specified band.

SB_Counts_Neg_Err
The 1-sigma lower statistical error (Gehrels 1986, ApJ, 303, 336) in the aperture-corrected net (i.e., background-subtracted) source counts in the specified band.

HB_Counts_Limit
This parameter is set to '<' if the source was not considered to be detected in the corresponding energy band, else is left blank.

HB_Counts
The aperture-corrected net (i.e., background-subtracted) source counts (or upper limit) for the standard hard (2.0 - 7.0 keV) band (computed in Section 2.2.2 of the reference paper). The authors treat a source as being "detected" for photometry purposes in a given band only if it satisfies P < 0.004 in that band. They calculate upper limits for sources not detected in a given band, according to the Bayesian method of Kraft et al. (1991, ApJ, 374, 344) for a 90% confidence level, and set the corresponding errors to null.

HB_Counts_Pos_Err
The 1-sigma upper statistical error (Gehrels 1986, ApJ, 303, 336) in the aperture-corrected net (i.e., background-subtracted) source counts in the specified band.

HB_Counts_Neg_Err
The 1-sigma upper statistical error (Gehrels 1986, ApJ, 303, 336) in the aperture-corrected net (i.e., background-subtracted) source counts in the specified band.

PSF_Flag
A flag indicating whether a source shows a radial profile consistent with that of the local PSF. This analysis is motivated by the fact that the use of 9 wavelet scales up to 16 pixels in the WAVDETECT runs in Section 2.2.2 of the reference paper potentially allows for the detection of extended sources on such scales compared to local PSFs. From the merged PSF image, the authors initially derive a set of cumulative encircle energy fractions (EEFs) by means of extracting the PSF power within a series of circular apertures up to a 90% EEF radius. From the merged source image, they subsequently derive another set of cumulative EEFs by means of extracting source counts within a series of circular apertures up to the same 90% EEF. Finally, they make use of a Kolmogorov-Smirnov (K-S) test to calculate the probability rho(K-S) of the two sets of cumulative EEFs being consistent with each other. Of the 683 main-catalog sources, the authors find that all but 15 have rho(K-S) > 0.05, i.e., these sources have radial profiles consistent with those of their corresponding PSFs above a 95% confidence level (thus being likely point-like sources), and set the value of this parameter to 1 for these sources. They then set the value of this parameter to 0 for the 15 sources with rho(K-S) <= 0.05, which are located across the entire CDF-N field and show no pattern of spatial clustering. Furthermore, the authors visually inspect these 15 sources and do not find any significant signature of extension.

OIR_RA
The Right Ascension of the primary optical/near-IR/mid-IR/radio (ONIR) counterpart to the Chandra X-ray source in the selected equinox. For supplementary catalog source (entries with source_sample = "Supp"), the position of the WIRCam Ks-band source is adopted. This position has been shifted accordingly to be consistent with the Ks-band astrometric frame; see Section 2.3.3 of the reference paper). Sources without ONIR counterparts have null values for this parameter. The ONIR counterpart RA was given in J2000.0 sexagesimal coordinates to a precision of 0.01 seconds of time in the original table.

OIR_Dec
The Declination of the primary optical/near-IR/mid-IR/radio (ONIR) counterpart to the Chandra X-ray source in the selected equinox. For supplementary catalog source (entries with source_sample = "Supp"), the position of the WIRCam Ks-band source is adopted. This position has been shifted accordingly to be consistent with the Ks-band astrometric frame; see Section 2.3.3 of the reference paper). Sources without ONIR counterparts have null values for this parameter. The ONIR counterpart Declination was given in J2000.0 sexagesimal coordinates to a precision of 0.1 arcseconds in the original table.

Offset
The offset between the X-ray source and the primary ONIR counterpart positions, in units of arcseconds. Sources without ONIR counterparts have this parameter set to null.

OIR_Ctrpart_Mag
The AB magnitude of the primary ONIR counterpart in the counterpart-detection band. For supplementary catalog source (entries with source_sample = "Supp"), the magnitude of the WIRCam Ks-band source is adopted. Sources without ONIR counterparts have this parameter set to null. The radio AB magnitudes are converted from the radio flux densities fnu using m(AB) = -2.5*log(fnu) - 48.60.

OIR_Ctrpart_Catalog
The name of the ONIR catalog (i.e., VLA, GOODS-N, CANDELS, Ks, CapakR/Yang14, or IRAC; see Section 2.3.3 of the reference paper) in which the primary counterpart is found. Sources without ONIR counterparts have a blank value for this parameter.

VLA_RA
The Right Ascension of the VLA 1.4-GHz counterpart to the Chandra X-ray source in the selected equinox. This position has been shifted accordingly to be consistent with the Ks-band astrometric frame; see Section 2.3.3 of the reference paper). Sources without counterparts have null values for this parameter. The counterpart RA was given in J2000.0 sexagesimal coordinates to a precision of 0.01 seconds of time in the original table. The authors match the position of the primary ONIR counterpart with the six ONIR catalogs using a matching radius of 0.5 arcseconds. They find that 31.3% of the main-catalog sources have VLA counterparts.

VLA_Dec
The Declination of the VLA 1.4-GHz counterpart to the Chandra X-ray source in the selected equinox. This position has been shifted accordingly to be consistent with the Ks-band astrometric frame; see Section 2.3.3 of the reference paper). Sources without counterparts have null values for this parameter. The counterpart Declination was given in J2000.0 sexagesimal coordinates to a precision of 0.1 arcseconds in the original table. The authors match the position of the primary ONIR counterpart with the six ONIR catalogs using a matching radius of 0.5 arcseconds. They find that 31.3% of the main-catalog sources have VLA counterparts.

VLA_Mag
The AB magnitude of the VLA 1.4-GHz counterpart to the Chandra X-ray source. Sources without such counterparts have this parameter set to null. The radio AB magnitudes are converted from the radio flux densities fnu using m(AB) = -2.5*log(fnu) - 48.60.

Goodsn_RA
The Right Ascension of the GOODS-N z-band counterpart to the Chandra X-ray source in the selected equinox. This position has been shifted accordingly to be consistent with the Ks-band astrometric frame; see Section 2.3.3 of the reference paper). Sources without counterparts have null values for this parameter. The counterpart RA was given in J2000.0 sexagesimal coordinates to a precision of 0.01 seconds of time in the original table. The authors match the position of the primary ONIR counterpart with the six ONIR catalogs using a matching radius of 0.5 arcseconds. They find that 55.2% of the main-catalog sources have GOODS-N counterparts.

Goodsn_Dec
The Declination of the GOODS-N z-band counterpart to the Chandra X-ray source in the selected equinox. This position has been shifted accordingly to be consistent with the Ks-band astrometric frame; see Section 2.3.3 of the reference paper). Sources without counterparts have null values for this parameter. The counterpart Declination was given in J2000.0 sexagesimal coordinates to a precision of 0.1 arcseconds in the original table. The authors match the position of the primary ONIR counterpart with the six ONIR catalogs using a matching radius of 0.5 arcseconds. They find that 55.2% of the main-catalog sources have GOODS-N counterparts.

Goodsn_Mag
The AB magnitude of the GOODS-N z-band counterpart to the Chandra X-ray source. Sources without such counterparts have this parameter set to null.

Candels_RA
The Right Ascension of the CANDELS F160W-band counterpart to the Chandra X-ray source in the selected equinox. This position has been shifted accordingly to be consistent with the Ks-band astrometric frame; see Section 2.3.3 of the reference paper). Sources without counterparts have null values for this parameter. The counterpart RA was given in J2000.0 sexagesimal coordinates to a precision of 0.01 seconds of time in the original table. The authors match the position of the primary ONIR counterpart with the six ONIR catalogs using a matching radius of 0.5 arcseconds. They find that 57.2% of the main-catalog sources have CANDELS counterparts.

Candels_Dec
The Declination of the CANDELS F160W-band counterpart to the Chandra X-ray source in the selected equinox. This position has been shifted accordingly to be consistent with the Ks-band astrometric frame; see Section 2.3.3 of the reference paper). Sources without counterparts have null values for this parameter. The counterpart Declination was given in J2000.0 sexagesimal coordinates to a precision of 0.1 arcseconds in the original table. The authors match the position of the primary ONIR counterpart with the six ONIR catalogs using a matching radius of 0.5 arcseconds. They find that 57.2% of the main-catalog sources have CANDELS counterparts.

Candels_Mag
The AB magnitude of the CANDELS F160W-band counterpart to the Chandra X-ray source. Sources without such counterparts have this parameter set to null.

Wircam_RA
The Right Ascension of the GOODS-N WIRCam Ks-band catalog (called "K_s_" in the oir_ctrpart_catalog parameter) counterpart to the Chandra X-ray source in the selected equinox. This position has been shifted accordingly to be consistent with the Ks-band astrometric frame; see Section 2.3.3 of the reference paper). Sources without counterparts have null values for this parameter. The counterpart RA was given in J2000.0 sexagesimal coordinates to a precision of 0.01 seconds of time in the original table. The authors match the position of the primary ONIR counterpart with the six ONIR catalogs using a matching radius of 0.5 arcseconds. They find that 91.7% of the main-catalog sources have WIRCam Ks counterparts.

Wircam_Dec
The Declination of the GOODS-N WIRCam Ks-band catalog (called "K_s_" in the oir_ctrpart_catalog parameter) counterpart to the Chandra X-ray source in the selected equinox. This position has been shifted accordingly to be consistent with the Ks-band astrometric frame; see Section 2.3.3 of the reference paper). Sources without counterparts have null values for this parameter. The counterpart Declination was given in J2000.0 sexagesimal coordinates to a precision of 0.1 arcseconds in the original table. The authors match the position of the primary ONIR counterpart with the six ONIR catalogs using a matching radius of 0.5 arcseconds. They find that 91.7% of the main-catalog sources have WIRCam Ks counterparts.

Wircam_Mag
The AB magnitude of the CFHT/WIRCam Ks-band counterpart to the Chandra X-ray source. Sources without such counterparts have this parameter set to null.

Supcam_RA
The Right Ascension of the H-HDF-N Suprime-Cam R-band catalog (called "CapakR" in the oir_ctrpart_catalog parameter) or the H-HDF-N photometric redshift catalog (called "Yang14" in the oir_ctrpart_catalog parameter) counterpart to the Chandra X-ray source in the selected equinox. This position has been shifted accordingly to be consistent with the Ks-band astrometric frame; see Section 2.3.3 of the reference paper). Sources without counterparts have null values for this parameter. The counterpart RA was given in J2000.0 sexagesimal coordinates to a precision of 0.01 seconds of time in the original table. The authors match the position of the primary ONIR counterpart with the six ONIR catalogs using a matching radius of 0.5 arcseconds. They find that 68.5% of the main-catalog sources have CapakR or Yang14 counterparts.

Supcam_Dec
The Declination of the H-HDF-N Suprime-Cam R-band catalog (called "CapakR" in the oir_ctrpart_catalog parameter) or the H-HDF-N photometric redshift catalog (called "Yang14" in the oir_ctrpart_catalog parameter) counterpart to the Chandra X-ray source in the selected equinox. This position has been shifted accordingly to be consistent with the Ks-band astrometric frame; see Section 2.3.3 of the reference paper). Sources without counterparts have null values for this parameter. The counterpart Declination was given in J2000.0 sexagesimal coordinates to a precision of 0.1 arcseconds in the original table. The authors match the position of the primary ONIR counterpart with the six ONIR catalogs using a matching radius of 0.5 arcseconds. They find that 68.5% of the main-catalog sources have CapakR or Yang14 counterparts.

Supcam_Mag
The AB magnitude of the Subaru/Suprime-Cam R-band counterpart to the Chandra X-ray source. Sources without such counterparts have this parameter set to null.

IRAC_RA
The Right Ascension of the SEDS IRAC 3.6-micron-band catalog (called "IRAC" in the oir_ctrpart_catalog parameter) counterpart to the Chandra X-ray source in the selected equinox. This position has been shifted accordingly to be consistent with the Ks-band astrometric frame; see Section 2.3.3 of the reference paper). Sources without counterparts have null values for this parameter. The counterpart RA was given in J2000.0 sexagesimal coordinates to a precision of 0.01 seconds of time in the original table. The authors match the position of the primary ONIR counterpart with the six ONIR catalogs using a matching radius of 0.5 arcseconds. They find that 87.0% of the main-catalog sources have IRAC counterparts.

IRAC_Dec
The Declination of the SEDS IRAC 3.6-micron-band catalog (called "IRAC" in the oir_ctrpart_catalog parameter) counterpart to the Chandra X-ray source in the selected equinox. This position has been shifted accordingly to be consistent with the Ks-band astrometric frame; see Section 2.3.3 of the reference paper). Sources without counterparts have null values for this parameter. The counterpart Declination was given in J2000.0 sexagesimal coordinates to a precision of 0.01 arcseconds in the original table. The authors match the position of the primary ONIR counterpart with the six ONIR catalogs using a matching radius of 0.5 arcseconds. They find that 87.0% of the main-catalog sources have IRAC counterparts.

IRAC_3p6_um_Mag
The AB magnitude of the Spitzer/IRAC 3.6-um counterpart to the Chandra X-ray source. Sources without such counterparts have this parameter set to null.

Spec_Redshift
The spectroscopic redshift (zspec) of the source. Only secure zspec values are collected, and they come from the following:

  (1) Barger et al. (2008, ApJ, 689, 687),
  (2) Cowie et al. (2004, AJ, 127, 3137),
  (3) Wirth et al. (2004, AJ, 127, 3121),
  (4) Cooper et al. (2011, ApJS, 193, 14),
  (5) Chapman et al. (2005, ApJ, 622, 772),
  (6) Barger et al. (2003, AJ, 126, 632), and
  (7) Skelton et al. (2014, ApJS, 214, 24).
  
The authors match the positions of primary ONIR counterparts with the above zspec catalogs utilizing a 0.5 arcseconds matching radius. For the 670 main-catalog sources with ONIR counterparts, they find that 351 (52.4%) have zspec measurements (307/351 = 87.5% have R <= 24 mag and 44/351 = 12.5% have R > 24 mag). Sources without zspec have this parameter set to null.

Ref_Spec_Redshift
The reference code for the secure spectroscopic redshift of the source, coded as follows:

  (1) Barger et al. (2008,ApJ, 689, 687),
  (2) Cowie et al. (2004, AJ, 127, 3137),
  (3) Wirth et al. (2004, AJ, 127, 3121),
  (4) Cooper et al. (2011, ApJS, 193, 14),
  (5) Chapman et al. (2005, ApJ, 622, 772),
  (6) Barger et al. (2003, AJ, 126, 632),
  (7) Skelton et al. (2014, ApJS, 214, 24).
  

Phot_Redshift
The photometric-redshift (zphot) information on the source taken from the literature. The authors match the position of primary ONIR counterparts with zphot catalogs utilizing a 0.5 arcseconds matching radius. Of the 670 main-catalog sources with ONIR counterparts, 612 (91.3%) and 389 (58.1%) have zphot estimates from Yang et al. (2014, ApJS, 215, 27) and Skelton et al. (2014, ApJS, 214, 24), respectively. Sources without available zphot estimates have this parameter set to null.

Phot_Redshift_Min
The 1-sigma lower bound to the photometric redshift (zphot) of the source.

Phot_Redshift_Max
The 1-sigma upper bound to the photometric redshift (zphot) of the source.

Phot_Redshift_Flag
The value of the quality flag Qz for the photometric redshift of the source. Smaller Qz values denote better quality, with 0 < Qz <~ 1 indicating a reliable zphot estimate.

Phot_Redshift_Alt
An alternative photometric redshift for the source taken from the literature. The authors match the position of primary ONIR counterparts with zphot catalogs utilizing a 0.5 arcseconds matching radius. Of the 670 main-catalog sources with ONIR counterparts, 612 (91.3%) and 389 (58.1%) have zphot estimates from Yang et al. (2014, ApJS, 215, 27) and Skelton et al. (2014, ApJS, 214, 24), respectively. Sources without available zphot estimates have this parameter set to null.

Phot_Class
The likely photometric classification ("Galaxy", "Star", or "Xray_AGN") from the H-HDF-N zphot catalog of Yang et al. (2004, ApJS, 215, 27). Sources without this information have this parameter set to null.

Phot_Redshift_Sk
The photometric-redshift (zphot) information on the source taken from the CANDELS/3D-HST zphot catalog of Skelton et al. (2014, ApJS, 214, 24). The authors match the position of primary ONIR counterparts with zphot catalogs utilizing a 0.5 arcseconds matching radius. Of the 670 main-catalog sources with ONIR counterparts, 612 (91.3%) and 389 (58.1%) have zphot estimates from Yang et al. (2014, ApJS, 215, 27) and Skelton et al. (2014, ApJS, 214, 24), respectively. Sources without available zphot estimates have this parameter set to null.

Phot_Redshift_Sk_Min
The 1-sigma lower bound to the photometric redshift (zphot) of the source taken from Skelton et al. (2014).

Phot_Redshift_Sk_Max
The 1-sigma upper bound to the photometric redshift (zphot) of the source taken from Skelton et al. (2014).

Phot_Redshift_Sk_Flag
The value of the quality flag Qz for the photometric redshift of the source taken from Skelton et al. (2014).. Smaller Qz values denote better quality, with 0 < Qz <~ 1 indicating a reliable zphot estimate.

Phot_Class_Sk
The likely photometric classification ("Galaxy" or "Star"), taken from the CANDELS/3D-HST zphot catalog of Skelton et al. (2014, ApJS, 214, 24). Sources without this information have this parameter set to null.

Redshift
The preferred redshift (zfinal) adopted in this work. The authors choose zfinal for a source in the following order of preference: secure zspec, the CANDELS/3D-HST zphot, and the H-HDF-N zphot. Of the 670 main-catalog sources with ONIR counterparts, 638 (95.2%) have zspec or zphot values.

A03_Source_Number
The corresponding source ID number in the Alexander et al. (2003, AJ, 126, 539, hereafter A03) 2-Ms CDF-N catalogs (the main catalog of which is available in the HEASARC database as the CHANDFN2MS table). The authors match their X-ray source positions to the A03 source positions (shifted accordingly to be consistent with the Ks-band astrometric frame) using a 2.5-arcsecond matching radius for sources having off-axis angles < 6 arcminutes and a 4.0-arcsecond matching radius for sources having off-axis angles >= 6 arcminutes. Among the 683 main-catalog sources, they find that (1) 487 have matches in the 503-source A03 main catalog (the value of this parameter is that from Column 1 of Table 3(a) in A03), i.e., there are 196 (i.e., 683 - 487 = 196) new main-catalog sources (see Section 2.3.7 of the reference paper for more details of these 196 new sources), compared to the A03 main catalog; (2) 45 have matches in the 78-source A03 supplementary catalog (the value of this parameter is that from Column 1 of Table 7(a) in A03 added with a prefix of "SP_" added); and (3) 151 have no match in either the A03 main or supplementary catalogs, which are detected now thanks to the new two-stage source-detection approach (in such cases, the value of this column is set to null). The authors refer readers to Section 2.3.5 of the reference paper for information on the 16 A03 main-catalog sources that are not included in the present "Main" catalog sample.

A03_RA
The Right Ascension of the A03 counterpart to the Chandra X-ray source in the selected equinox. This position has been shifted accordingly to be consistent with the Ks-band astrometric frame; see Section 2.3.3 of the reference paper). Sources without counterparts have null values for this parameter. The counterpart RA was given in J2000.0 sexagesimal coordinates to a precision of 0.01 seconds of time in the original table.

A03_Dec
The Declination of the A03 counterpart to the Chandra X-ray source in the selected equinox. This position has been shifted accordingly to be consistent with the Ks-band astrometric frame; see Section 2.3.3 of the reference paper). Sources without counterparts have null values for this parameter. The counterpart Declination was given in J2000.0 sexagesimal coordinates to a precision of 0.1 arcseconds in the original table.

FB_Exposure
The effective exposure time at the position of the source in units of seconds derived from the exposure maps (see Section 2.2.1 of the reference paper) for the standard full (0.5 - 7.0 keV) band. Effective count rates that are corrected for effects of vignetting, quantum-efficiency degradation, and exposure time variations can be obtained by dividing the full-band counts (the fb_counts parameter) by this corresponding effective exposure time.

SB_Exposure
The effective exposure time at the position of the source in units of seconds derived from the exposure maps (see Section 2.2.1 of the reference paper) for the standard soft (0.5 - 2.0 keV) band. Effective count rates that are corrected for effects of vignetting, quantum-efficiency degradation, and exposure time variations can be obtained by dividing the soft-band counts (the sb_counts parameter) by this corresponding effective exposure time.

HB_Exposure
The effective exposure time at the position of the source in units of seconds derived from the exposure maps (see Section 2.2.1 of the reference paper) for the standard hard (2.0 - 7.0 keV) band. Effective count rates that are corrected for effects of vignetting, quantum-efficiency degradation, and exposure time variations can be obtained by dividing the hard-band counts (the hb_counts parameter) by this corresponding effective exposure time.

Band_Ratio
The band ratio of the Chandra source. The band ratio is defined as the ratio of effective count rates between the hard and soft bands. Band-ratio errors are computed according to the numerical error-propagation method detailed in Section 1.7.3 of Lyons (1991, Data Analysis for Physical Science Students), which avoids the failure of the standard approximate variance formula in the case of a small number of counts. Upper limits are computed for sources detected in the soft band but not the hard band, while lower limits are computed for sources detected in the hard band but not the soft band; for these sources, the upper and lower errors are set to the calculated band ratio. Band ratios and associated errors are set to null values for sources with full band detections only.

Band_Ratio_Pos_Err
The upper uncertainty in the band ratio.

Band_Ratio_Neg_Err
The lower uncertainty in the band ratio.

Photon_Index
The effective photon index Gamma of the Chandra X-ray source assuming a power-law model with the Galactic column density in the direction of the CDF-N NH of 1.6 x 1020 cm-2. Gamma is calculated based on the band ratio and a conversion between Gamma and the band ratio. This conversion is derived utilizing the band ratios and photon indices computed by the AE-automated XSPEC-fitting procedure for sources with > 200 full band counts. Upper limits are computed for sources detected in the hard band but not the soft band, while lower limits are computed for sources detected in the soft band but not the hard band; for these sources, the upper and lower errors are set to the calculated Gamma. A value of Gamma = 1.4 is assumed for low-count sources, being a representative value for faint sources that enables reasonable flux estimates, and the associated upper and lower errors are set to 0.00. Low-count sources are defined as those that were (1) detected in the soft band having < 30 counts and not detected in the hard band, (2) detected in the hard band having < 15 counts and not detected in the soft band, (3) detected in both the soft band and hard band, but having < 15 counts in each, or (4) detected only in the full band.

Photon_Index_Pos_Err
The upper uncertainty in the photon index of the Chandra X-ray source.

Photon_Index_Neg_Err
The lower uncertainty in the photon index of the Chandra X-ray source.

FB_Flux_Limit
This parameter is set to '<' if the source was not considered to be detected in the corresponding energy band, else is left blank.

FB_Flux
The observed-frame flux (or upper limit thereof) of the Chandra X-ray source, in units of erg cm-2 s-1, for the standard full band. Fluxes are calculated making use of the net counts and the effective exposure time in the corresponding band, and the photon index, Gamma, based on conversions derived from XSPEC-fitting results. Fluxes are not corrected for Galactic absorption or for any intrinsic absorption of the source.

SB_Flux_Limit
This parameter is set to '<' if the source was not considered to be detected in the corresponding energy band, else is left blank

SB_Flux
The observed-frame flux (or upper limit thereof) of the Chandra X-ray source, in units of erg cm-2 s-1, for the standard soft band. Fluxes are calculated making use of the net counts and the effective exposure time in the corresponding band, and the photon index, Gamma, based on conversions derived from XSPEC-fitting results. Fluxes are not corrected for Galactic absorption or for any intrinsic absorption of the source.

HB_Flux_Limit
This parameter is set to '<' if the source was not considered to be detected in the corresponding energy band, else is left blank

HB_Flux
The observed-frame flux (or upper limit thereof) of the Chandra X-ray source, in units of erg cm-2 s-1, for the standard hard band. Fluxes are calculated making use of the net counts and the effective exposure time in the corresponding band, and the photon index, Gamma, based on conversions derived from XSPEC-fitting results. Fluxes are not corrected for Galactic absorption or for any intrinsic absorption of the source.

Lx
A basic estimate of the absorption-corrected, rest-frame 0.5-7 keV luminosity Lx of the Chandra source, in units of erg s-1, computed according to the procedure presented in Section 3.4 of Xue et al. (2010, ApJ, 720, 368). A cosmology with H0 = 69.7 km s-1 Mpc-1, OmegaM = 0.282, and OmegaLambda = 0.718 (Hinshaw et al. 2013, ApJS, 208, 19) has been adopted. See Section 2.3.4 of the reference paper for more details. Sources without zfinal have this parameter set to null.

Broad_Type
A basic estimate of the likely source type: "AGN", "Galaxy", or "Star". A source is classified as an AGN once it satisfies at least one of the following four criteria (see Section 4.4 of Xue et al. (2011, ApJS. 195, 10) for reasoning and caveats):

     Lx >= 3 x 1042 erg s-1, i.e., luminous AGNs,

    Gamma <= 1.0, i.e., obscured AGNs,

    log (fx/fR) > -1, where fx is the full-, soft- or hard-band X-ray
                          flux and fR is the R-band flux, or

    Lx >~ 3 x (8.9 x 1017 LR), where LR is the rest-frame 1.4 GHz
                          monochromatic luminosity in units of W Hz-1.
  
A source is classified as a star if (1) it has zspec = 0, (2) it is one of the old late-type X-ray-detected CDF-N stars studied in Feigelson et al. (2004, ApJ, 611, 1107), or (3) it has a photometric classification of "Star" in this paper and is further confirmed through visual inspection of optical images. The sources that are not classified as either AGNs or stars are then regarded as "Galaxies". There are 591 (86.5%), 75 (11.0%), and 17 (2.5%) of the 683 main-catalog sources identified as AGNs, galaxies, and stars, respectively.

Note_Flag
This field contains brief notes on the sources. Sources in close doubles or triples are annotated with "C" (a total of 27 such sources, which have overlapping polygonal extraction regions corresponding to ~ 40-75% EEFs see Section 2.2.2 of the reference paper).

Class
The HEASARC Browse object classification based on the value of the broad_type parameter.


Contact Person

Questions regarding the CDFN2MSNEW database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 24-Aug-2016