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CHANDFN2MS - Chandra Deep Field North 2-Megasecond Catalog

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Overview

The Chandra Deep Field North (CDFN) 2-Megasecond Catalog contains the point sources found in the ~2 Megasecond (Ms) exposure of the Chandra Deep Field North, currently the deepest X-ray observation of the universe in the 0.5 -8.0 keV band. Five hundred and three (503) X-ray sources were detected over an ~448 square arcminute area in up to seven X-ray bands. Twenty (20) of these X-ray sources lie in the central ~5.3 square arcminute Hubble Deep Field North (13600 (+3800,-3000) sources/deg^2). The on-axis sensitivity limits are ~2.5x10^-17 ergs/cm^2/s (0.5 - 2.0 keV) and 1.4x10^-16 ergs/cm^2/s (2 - 8 keV). Source positions are determined using matched-filter and centroiding techniques; the median positional uncertainty is ~0.3". The X-ray colors of the detected sources indicate a broad variety of source types, although absorbed AGN (including a small number of possible Compton-thick sources) are clearly the dominant type. The average backgrounds in the 0.5 - 2.0 keV and 2 - 8 keV bands are 0.056 and 0.135 counts Ms^-1 pixel^-1, respectively. The background count distributions are very similar to Poisson distributions. This 2 Ms exposure is approximately photon limited in all seven X-ray bands for regions close to the aim point. This observation does not suffer from source confusion within ~6 arcminutes of the aim point.

Catalog Bibcode

2003AJ....126..539A

References

The Chandra Deep Field North Survey. XIII. 2 Ms point-source catalogs.
    Alexander D.M., Bauer F.E., Brandt W.N., Schneider D.P., Hornschemeier A.E.,
    Vignali C., Barger A.J., Broos P.S., Cowie L.L., Garmire G.P.,
    Townsley L.K., Bautz M.W., Chartas G., Sargent W.L.W.
   <Astron. J. 126, 539 (2003)>
   =2003AJ....126..539A

Provenance

This table was created by the HEASARC in April 2004 based on CDS catalog table J/AJ/126/539/cdfn.dat.

Parameters

Sequence_Number
The CDFN source number, a running number in order of increasing right ascension.

Name
The object designation using the prefix recommended by the Dictionary of Nomenclature of Celestial Objects and implemented in the CDS Simbad service. The authors describe an alternative form for these sources using the Chandra X-Ray Observatory (CXO) naming convention: the prefix "CXO HDFN J" together with the J2000 RA and declination, truncated to 0.1 seconds of time and 1 arcsecond, respectively. Thus, the object with sequence_number of 1 and the J2000 position of 12 35 15.04, +62 14 07.0 has the name of "[ABB2003] CDFN 1" here, and the alternate name of "CXO HDFN J123515.0+621407".

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

Dec
The Declination of the X-ray source in the selected equinox. This was given to 0.1 arcseconds and in the J2000 equinox in the original table.

LII
The Galactic Longitude of the X-ray source.

BII
The Galactic Latitude of the X-ray source.

Error_Radius
The positional uncertainty of the X-ray source. This is dependent on the off-axis angle and the number of detected counts. The stated positional uncertainties are for ~80% - 90% confidence.

Off_Axis_Angle
The off-axis angle of the source, in arcminutes, calculated using the source position and the average aim point.

Limit_FB_Counts
A limit flag for the full-band (0.5-8 keV) counts.

FB_Counts
The full-band (0.5-8.0 keV) counts for the standard ASCA grade set, and not corrected for vignetting. The source counts and their errors were calculated using circular aperture photometry centered at the listed source position.

FB_Counts_Pos_Err
The 1-sigma positive statistical error in the full-band counts.

FB_Counts_Neg_Err
The 1-sigma negative statistical error in the full-band counts.

Flag_FB_Counts
A flag for the full-band (0.5-8 keV) counts with the following possible values:

      a = Source was detected with the restricted ACIS grade set with a
           probability threshold of 10^-7
      b = Source was detected with the standard ASCA grade set with a
           probability threshold of 10^-5
      c = Source positional offset >2.5" from the primary source position
  

Limit_SB_Counts
A limit flag for the soft-band (0.5-2 keV) counts.

SB_Counts
The soft-band (0.5-2 keV) counts for the standard ASCA grade set, and not corrected for vignetting. The source counts and their errors were calculated using circular aperture photometry centered at the listed source position.

SB_Counts_Pos_Err
The 1-sigma positive statistical error in the soft-band counts.

SB_Counts_Neg_Err
The 1-sigma negative statistical error in the soft-band counts.

Flag_SB_Counts
A flag for the soft-band (0.5-2 keV) counts with the following possible values:

      a = Source was detected with the restricted ACIS grade set with a
           probability threshold of 10^-7
      b = Source was detected with the standard ASCA grade set with a
           probability threshold of 10^-5
      c = Source positional offset >2.5" from the primary source position
  

Limit_HB_Counts
A limit flag for the hard-band (2-8 keV) counts.

HB_Counts
The hard-band (2-8 keV) counts for the standard ASCA grade set, and not corrected for vignetting. The source counts and their errors were calculated using circular aperture photometry centered at the listed source position.

HB_Counts_Pos_Err
The 1-sigma positive statistical error in the hard-band counts.

HB_Counts_Neg_Err
The 1-sigma negative statistical error in the hard-band counts.

Flag_HB_Counts
A flag for the hard-band (2-8 keV) counts with the following possible values:

      a = Source was detected with the restricted ACIS grade set with a
           probability threshold of 10^-7
      b = Source was detected with the standard ASCA grade set with a
           probability threshold of 10^-5
      c = Source positional offset >2.5" from the primary source position
  

Limit_Sb1_Counts
A limit flag for the SB1-band (0.5-1 keV) counts.

SB1_Counts
The SB1 (0.5-1 keV) counts for the standard ASCA grade set, and not corrected for vignetting. The source counts and their errors were calculated using circular aperture photometry centered at the listed source position.

SB1_Counts_Pos_Err
The 1-sigma positive statistical error in the SB1-band counts.

SB1_Counts_Neg_Err
The 1-sigma negative statistical error in the SB1-band counts.

Flag_Sb1_Counts
A flag for the SB1-band (0.5-1 keV) counts with the following possible values:

      a = Source was detected with the restricted ACIS grade set with a
           probability threshold of 10^-7
      b = Source was detected with the standard ASCA grade set with a
           probability threshold of 10^-5
      c = Source positional offset >2.5" from the primary source position
  

Limit_Sb2_Counts
A limit flag for the SB2-band (1-2 keV) counts.

SB2_Counts
The SB2 (1-2 keV) counts for the standard ASCA grade set, and not corrected for vignetting. The source counts and their errors were calculated using circular aperture photometry centered at the listed source position.

SB2_Counts_Pos_Err
The 1-sigma positive statistical error in the SB2-band counts.

SB2_Counts_Neg_Err
The 1-sigma negative statistical error in the SB2-band counts.

Flag_Sb2_Counts
A flag for the SB2-band (1-2 keV) counts with the following possible values:

      a = Source was detected with the restricted ACIS grade set with a
           probability threshold of 10^-7
      b = Source was detected with the standard ASCA grade set with a
           probability threshold of 10^-5
      c = Source positional offset >2.5" from the primary source position
  

Limit_Hb1_Counts
A limit flag for the HB1-band (2-4 keV) counts.

HB1_Counts
The HB1 (2-4 keV) counts for the standard ASCA grade set, and not corrected for vignetting. The source counts and their errors were calculated using circular aperture photometry centered at the listed source position.

HB1_Counts_Pos_Err
The 1-sigma positive statistical error in the HB1-band counts.

HB1_Counts_Neg_Err
The 1-sigma negative statistical error in the HB1-band counts.

Flag_Hb1_Counts
A flag for the HB1-band (2-4 keV) counts with the following possible values:

      a = Source was detected with the restricted ACIS grade set with a
           probability threshold of 10^-7
      b = Source was detected with the standard ASCA grade set with a
           probability threshold of 10^-5
      c = Source positional offset >2.5" from the primary source position
  

Limit_Hb2_Counts
A limit flag for the HB2-band (4-8 keV) counts.

HB2_Counts
The HB2 (4-8 keV) counts for the standard ASCA grade set, and not corrected for vignetting. The source counts and their errors were calculated using circular aperture photometry centered at the listed source position.

HB2_Counts_Pos_Err
The 1-sigma positive statistical error in the HB2-band counts.

HB2_Counts_Neg_Err
The 1-sigma negative statistical error in the HB2-band counts.

Flag_Hb2_Counts
A flag for the HB2-band (4-8 keV) counts with the following possible values:

      a = Source was detected with the restricted ACIS grade set with a
           probability threshold of 10^-7
      b = Source was detected with the standard ASCA grade set with a
           probability threshold of 10^-5
      c = Source positional offset >2.5" from the primary source position
  

Source_Notes
A notes flag for the X-ray source with the following possible values:

      H = Denotes objects lying in the HDF-N (see Fig. 2 of paper)
      O = Refers to objects that have large cross-band positional offsets
           (>2.5") - all but one of these sources lie at off-axis angles
           of >6', and the flagged counterpart may not be associated with
           the main counterpart in some cases
      M = Refers to sources where the photometry was performed manually
      S = Refers to close double sources where manual separation was required
      R = Refers to radio-detected sources that were used in determining
           the astrometric accuracy (see section 3.3 of paper)
      HB3 = Refers to a detection in the 6-8 keV band
  

Exposure
The effective exposure time, in seconds (s), derived from the full-band exposure map. Dividing the counts given by parameters such as fb_counts by the effective exposure will provide vignetting-corrected count rates. This parameter was given with a precision of 0.1 kiloseconds in the original, as-published table.

Limit_Ratio_1
A limit flag for the main band ratio, ratio_1.

Ratio_1
The main band ratio, defined as the ratio of counts between the hard and soft bands. Quoted band ratios have been corrected for differential vignetting between the hard and the soft bands using the appropriate exposure maps.

Ratio_1_Pos_Err
The positive 1-sigma Error in the main band ratio, calculated using the "numerical method" described in Section 1.7.3 of Lyons (1991, Data Analysis for Physical Science Students). Note that the error distribution is not Gaussian when the number of counts is small.

Ratio_1_Neg_Err
The negative 1-sigma Error in the main band ratio, calculated using the "numerical method" described in Section 1.7.3 of Lyons (1991, Data Analysis for Physical Science Students). Note that the error distribution is not Gaussian when the number of counts is small.

Limit_Photon_Index
A limit flag for the effective photon index.

Photon_Index
The effective photon index for a power-law model with the Galactic column density, taking into account the continuous ACIS quantum efficiency degradation. The effective photon index has been calculated based on the main band ratio, ratio_1, when the number of counts is not low. When the number of counts is low, the photon index is poorly constrained and set to 1.4, a representative value for faint sources that should give reasonable fluxes: this is indicated by the value of the flag_photon_index being set to "a".

Flag_Photon_Index
A flag for the effective photon index that is set to "a" when the number of counts is low, indicating that the photon index is poorly constrained and has been set to 1.4, a representative value for faint sources that should give reasonable fluxes.

Photon_Index_Pos_Err
The positive 1-sigma error in the effective photon index.

Photon_Index_Neg_Err
The negative 1-sigma error in the effective photon index.

Limit_FB_Flux
A limit flag for the full-band (0.5-8 keV) flux.

FB_Flux
The observed-frame flux in the full (0.5-8.0 keV) band, in units of erg cm^-2 s^-1. Fluxes have been computed using the listed counts, the appropriate exposure maps, and the spectral slopes given by the photon_index parameter. They have not been corrected for absorption by the Galaxy or material intrinsic to the source; however, the fluxes have been adjusted to take into account the continuous ACIS quantum efficiency degradation.

Limit_SB_Flux
A limit flag for the soft-band (0.5-2 keV) flux.

SB_Flux
The observed-frame flux in the soft (0.5-2.0 keV) band, in units of erg cm^-2 s^-1. Fluxes have been computed using the listed counts, the appropriate exposure maps, and the spectral slopes given by the photon_index parameter. They have not been corrected for absorption by the Galaxy or material intrinsic to the source; however, the fluxes have been adjusted to take into account the continuous ACIS quantum efficiency degradation.

Limit_HB_Flux
A limit flag for the hard-band (2-8 keV) flux.

HB_Flux
The observed-frame flux in the hard (2-8 keV) band, in units of erg cm^-2 s^-1. Fluxes have been computed using the listed counts, the appropriate exposure maps, and the spectral slopes given by the photon_index parameter. They have not been corrected for absorption by the Galaxy or material intrinsic to the source; however, the fluxes have been adjusted to take into account the continuous ACIS quantum efficiency degradation.

Limit_Sb1_Flux
A limit flag for the SB1-band (0.5-1 keV) flux.

SB1_Flux
The observed-frame flux in the SB1 (0.5-1 keV) band, in units of erg cm^-2 s^-1. Fluxes have been computed using the listed counts, the appropriate exposure maps, and the spectral slopes given by the photon_index parameter. They have not been corrected for absorption by the Galaxy or material intrinsic to the source; however, the fluxes have been adjusted to take into account the continuous ACIS quantum efficiency degradation.

Limit_Sb2_Flux
A limit flag for the SB2-band (1-2 keV) flux.

SB2_Flux
The observed-frame flux in the SB2 (1-2 keV) band, in units of erg cm^-2 s^-1. Fluxes have been computed using the listed counts, the appropriate exposure maps, and the spectral slopes given by the photon_index parameter. They have not been corrected for absorption by the Galaxy or material intrinsic to the source; however, the fluxes have been adjusted to take into account the continuous ACIS quantum efficiency degradation.

Limit_Hb1_Flux
A limit flag for the HB1-band (2-4 keV) flux.

HB1_Flux
The observed-frame flux in the HB1 (2-4 keV) band, in units of erg cm^-2 s^-1. Fluxes have been computed using the listed counts, the appropriate exposure maps, and the spectral slopes given by the photon_index parameter. They have not been corrected for absorption by the Galaxy or material intrinsic to the source; however, the fluxes have been adjusted to take into account the continuous ACIS quantum efficiency degradation.

Limit_Hb2_Flux
A limit flag for the HB2-band (4-8 keV) flux.

HB2_Flux
The observed-frame flux in the HB2 (4-8 keV) band, in units of erg cm^-2 s^-1. Fluxes have been computed using the listed counts, the appropriate exposure maps, and the spectral slopes given by the photon_index parameter. They have not been corrected for absorption by the Galaxy or material intrinsic to the source; however, the fluxes have been adjusted to take into account the continuous ACIS quantum efficiency degradation.

Limit_Ratio_2
A limit flag for the SB2/SB1 bands count ratio, ratio_2.

Ratio_2
The ratio of counts between the SB2 and SB1 bands. Quoted band ratios have been corrected for differential vignetting between the hard and the soft bands using the appropriate exposure maps.

Ratio_2_Pos_Err
The positive 1-sigma Error in the SB2/SB1 band ratio, calculated using the "numerical method" described in Section 1.7.3 of Lyons (1991, Data Analysis for Physical Science Students). Note that the error distribution is not Gaussian when the number of counts is small.

Ratio_2_Neg_Err
The negative 1-sigma Error in the SB2/SB1 band ratio, calculated using the "numerical method" described in Section 1.7.3 of Lyons (1991, Data Analysis for Physical Science Students). Note that the error distribution is not Gaussian when the number of counts is small.

Limit_Ratio_3
A limit flag for the HB2/HB1 bands count ratio, ratio_3.

Ratio_3
The ratio of counts between the HB2 and HB1 bands. Quoted band ratios have been corrected for differential vignetting between the hard and the soft bands using the appropriate exposure maps.

Ratio_3_Pos_Err
The positive 1-sigma Error in the HB2/HB1 band ratio, calculated using the "numerical method" described in Section 1.7.3 of Lyons (1991, Data Analysis for Physical Science Students). Note that the error distribution is not Gaussian when the number of counts is small.

Ratio_3_Neg_Err
The negative 1-sigma Error in the HB2/HB1 band ratio, calculated using the "numerical method" described in Section 1.7.3 of Lyons (1991, Data Analysis for Physical Science Students). Note that the error distribution is not Gaussian when the number of counts is small.

Limit_Ratio_4
A limit flag for the HB1/SB2 bands count ratio, ratio_4.

Ratio_4
The ratio of counts between the HB1 and SB2 bands. Quoted band ratios have been corrected for differential vignetting between the hard and the soft bands using the appropriate exposure maps.

Ratio_4_Pos_Err
The positive 1-sigma Error in the HB1/SB2 band ratio, calculated using the "numerical method" described in Section 1.7.3 of Lyons (1991, Data Analysis for Physical Science Students). Note that the error distribution is not Gaussian when the number of counts is small.

Ratio_4_Neg_Err
The negative 1-sigma Error in the HB1/SB2 band ratio, calculated using the "numerical method" described in Section 1.7.3 of Lyons (1991, Data Analysis for Physical Science Students). Note that the error distribution is not Gaussian when the number of counts is small.


Contact Person

Questions regarding the CHANDFN2MS database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 8-Aug-2006