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CHANEXTDFS - Chandra Extended Deep Field South Survey Point Source Catalog

HEASARC
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Overview

This table contains the combined point-source catalogs for the Extended Chandra Deep Field- South (E-CDF-S) survey. The E-CDF-S consists of four contiguous 250 ks Chandra observations covering an approximately square region of total solid angle ~0.3 square degrees, which flank the existing ~1 Ms Chandra Deep Field-South (CDF-S). The survey reaches sensitivity limits of ~1.1 x 10^-16 and ~6.7 x 10^-16 ergs cm^-2 s^-1 for the 0.5-2.0 and 2-8 keV bands, respectively. 762 distinct X-ray point sources are detected within the E-CDF-S exposure; 589 of these sources are new (i.e., not previously detected in the ~1 Ms CDF-S). This brings the total number of X-ray point sources detected in the E-CDF-S region to 915 (via the E-CDF-S and ~1 Ms CDF-S observations). Source positions are determined using matched-filter and centroiding techniques; the median positional uncertainty is ~0.35". The basic X-ray and optical properties of these sources indicate a variety of source types, although absorbed active galactic nuclei (AGNs) seem to dominate. In addition to the main Chandra catalog, this table contains the supplementary source catalog with 33 lower-significance X-ray point sources that have bright optical counterparts (R < 23 mag). These sources generally have X-ray-to-optical flux ratios expected for normal and starburst galaxies, which lack a strong AGN component. The basic number-count results for the main Chandra catalog are in good agreement with the ~1 Ms CDF-S for sources with 0.5-2.0 and 2-8 keV fluxes greater than 3 x 10^-16 and 1 x 10^-15 ergs cm^-2 s^-1, respectively.

This HEASARC table contains 809 entries: 762 entries corresponding to the 762 sources listed in the main catalog (Table 2 of the published paper), 14 sources from the cross-field source list (Table 3) which give properties for sources which were detected in more than one observational sources, e.g. there are two entries for the source with source_number = 367, one entry coming from the main catalog, the other entry from the cross-field catalog, and 33 entries corresponding to the 33 sources in the supplementary, optically bright source catalog (Table 6). The HEASARC has created a new parameter called source_type to identify from which of these 3 original tables any given entry comes from; it is set to 'main', 'crossfield' and 'supplement' for entries from Tables 2, 3, and 6, respectively.


Catalog Bibcode

2005ApJS..161...21L

References

The Extended Chandra Deep Field-South Survey: Chandra Point-Source Catalogs.
    Lehmer, B. D., Brandt, W. N., Alexander, D. M., Bauer, F. E.,
    Schneider, D. P., Tozzi, P., Bergeron, J., Garmire, G. P., Giacconi, R.,
    Gilli, R., Hasinger, G., Hornschemeier, A. E., Koekemoer, A. M.,
    Mainieri, V., Miyaji, T., Nonino, M., Rosati, P., Silverman, J. D.,
    Szokoly, G., Vignali, C.
   <Astrophys. J. Suppl. Ser. 161, 21 (2005)>
   =2005ApJS..161...21L

Provenance

This online catalog was created by the HEASARC in January 2006 based on machine-readable versions of tables 2, 3, and 6 from the paper which were obtained from the ApJ website.

Parameters

Name
The recommended source designation for objects in this catalog, based on the IAU-registered 'CXOECDFS' prefix for 'Chandra X-ray Observatory Extended Chandra Deep Field-South' and the J2000 X-ray source position.

Source_Number
The source number, a unique identifier in order of ascending J2000 Right Ascension for objects from a given table. Entries from Tables 2/3 (source_type values of 'main' or 'crossfield') have one set of source_number values, notice, whereas entries from Table 6 (source_type = 'supplement') have a different set. Thus, to avoid confusion, entries should be identified by their name rather than their source_number.

Source_Type
This HEASARC-created parameter identifies from which of the 3 original tables used to create this HEASARC table any given entry comes from: it is set to 'main', 'crossfield' and 'supplement' for entries from Tables 2, 3, and 6, respectively.

RA
The Right Ascension of the 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 table. Note that more accurate positions are available for sources detected near the aim point of the ~1 Ms CDF-S through the catalogs presented in A03 (Alexander et al. 2003, AJ, 126, 539), and are provided in the parameters a03_ra_j2000 and a03_dec_j2000. For the faint sources from Table 6 (source_type = 'supplement'), the wavdetect positions are given.

Dec
The Declination of the X-ray source in the selected equinox. This was given in J2000 equatorial coordinates and to a precision of 0.1 arcseconds in the original table. Note that more accurate positions are available for sources detected near the aim point of the ~1 Ms CDF-S through the catalogs presented in A03 (Alexander et al. 2003, AJ, 126, 539), and are provided in the parameters a03_ra_j2000 and a03_dec_j2000. For the faint sources from Table 6 (source_type = 'supplement'), the wavdetect positions are given.

LII
The Galactic Longitude of the X-ray source.

BII
The Galactic Latitude of the X-ray source.

Error_Radius
The X-ray source positional uncertainty, in arcseconds. This is dependent on the off-axis angle and the number of source counts, as discussed in Section 3.3.1 of the published paper. The stated values are somewhat conservative, corresponding to the ~80-90% confidence level. For the faint X-ray sources from Table 6 (source_type = 'supplement'), the positional uncertainty is taken to be 1.2", the 90th percentile of the average optical-X-ray positional offset.

Off_Axis_Angle
The off-axis angle of the source from the aim point in the corresponding field in which it was detected, in arcminutes.

FB_Counts_Limit
This parameter is set to '<' if the quoted counts in this band correspond to an upper limit rather than a detection. In the original published tables, upper limits were indicated by the associated error parameters having values of -1.

FB_Counts
The net background-subtracted counts in the full band (0.5-8.0 keV). All values are for the standard ASCA grade set, and have not been corrected for vignetting. Source counts and statistical errors have been calculated using circular aperture photometry with the aperture centered at the position given by the parameters ra and dec for all bands. For the faint X-ray sources from Table 6 (source_type = 'supplement'), the photometry is taken directly from wavdetect.

FB_Counts_Pos_Err
The upper 1-sigma statistical error in the full-band counts. The errors quoted are calculated using the approximations from Gehrels (1986ApJ...303..336G).

FB_Counts_Neg_Err
The lower 1-sigma statistical error in the full-band counts. The errors quoted are calculated using the approximations from Gehrels (1986ApJ...303..336G).

SB_Counts_Limit
This parameter is set to '<' if the quoted counts in this band correspond to an upper limit rather than a detection. In the original published tables, upper limits were indicated by the associated error parameters having values of -1.

SB_Counts
The net background-subtracted counts in the soft band (0.5-2.0 keV). All values are for the standard ASCA grade set, and have not been corrected for vignetting. Source counts and statistical errors have been calculated using circular aperture photometry with the aperture centered at the position given by the parameters ra and dec for all bands. For the faint X-ray sources from Table 6 (source_type = 'supplement'), the photometry is taken directly from wavdetect.

SB_Counts_Pos_Err
The upper 1-sigma statistical error in the soft-band counts. The errors quoted are calculated using the approximations from Gehrels (1986ApJ...303..336G).

SB_Counts_Neg_Err
The lower 1-sigma statistical error in the soft-band counts. The errors quoted are calculated using the approximations from Gehrels (1986ApJ...303..336G).

HB_Counts_Limit
This parameter is set to '<' if the quoted counts in this band correspond to an upper limit rather than a detection. In the original published tables, upper limits were indicated by the associated error parameters having values of -1.

HB_Counts
The net background-subtracted counts in the hard band (2.0-8.0 keV). All values are for the standard ASCA grade set, and have not been corrected for vignetting. Source counts and statistical errors have been calculated using circular aperture photometry with the aperture centered at the position given by the parameters ra and dec for all bands. For the faint X-ray sources from Table 6 (source_type = 'supplement'), the photometry is taken directly from wavdetect.

HB_Counts_Pos_Err
The upper 1-sigma statistical error in the hard-band counts. The errors quoted are calculated using the approximations from Gehrels (1986ApJ...303..336G).

HB_Counts_Neg_Err
The lower 1-sigma statistical error in the hard-band counts. The errors quoted are calculated using the approximations from Gehrels (1986ApJ...303..336G).

RA_Optical_J2000
The Right Ascension of the optical source centroid, in fixed (J2000) sexagesimal coordinates. This was given in J2000 coordinates to a precision of 0.01 seconds of time in the original table, and was obtained by matching the X-ray source positions to WFI R-band positions using a matching radius of 1.5 times the positional uncertainty. For a small number of sources more than one optical match was found, and for these sources the brightest match was selected as the most probable counterpart. Sources with no optical counterparts have blank optical RA and Dec values.

Dec_Optical_J2000
The Declination of the optical source centroid, in fixed (J2000) sexagesimal coordinates. This was given in J2000 coordinates to a precision of 0.1 arcseconds in the original table, and was obtained by matching the X-ray source positions to WFI R-band positions using a matching radius of 1.5 times the positional uncertainty. For a small number of sources more than one optical match was found, and for these sources the brightest match was selected as the most probable counterpart. Sources with no optical counterparts have blank optical RA and Dec values.

Offset
The measured offset between the optical and X-ray source positions (O-X), in arcseconds. Sources with no optical counterparts have had their offset values set to 0.

Rmag
The R-Band AB Magnitude of the optical counterpart to the X-ray source. Sources with no optical counterparts have had their rmag values set to 0.

A03_Source_Number
The ~1 Ms CDF-S source number from the main Chandra catalog presented in A03 (Alexander et al. 2003, AJ, 126, 539) for E-CDF-S sources that were matched to A03 counterparts.

A03_RA_J2000
The J2000 Right Ascension of the corresponding ~ 1Ms A03 CDF-S source in sexagesimal coordinates.

A03_Dec_J2000
The J2000 Declination of the corresponding ~ 1Ms A03 CDF-S source in sexagesimal coordinates.

G02_Source_Number
The ~1 Ms CDF-S source number from the main Chandra catalog presented in G02 (Giacconi et al. 2002, ApJS, 139, 369) for E-CDF-S sources that were matched to G02 counterparts.

G02_RA_J2000
The J2000 Right Ascension of the corresponding ~1 Ms G02 CDF-S source in sexagesimal coordinates corrected for an offset of -1.2" as noted in the paper.

G02_Dec_J2000
The J2000 Declination of the corresponding ~1 Ms G02 CDF-S source in sexagesimal coordinates corrected for an offset of +0.8" as noted in the paper.

Exposure
The effective exposure time, in seconds (s), for the full-band, as derived from the standard-band exposure maps. Dividing the corresponding counts in this band by this exposure will provide the vignetting-corrected and quantum efficiency degradation-corrected count rate.

SB_Exposure
The effective exposure time, in seconds (s), for the soft-band, as derived from the standard-band exposure maps. Dividing the corresponding counts in this band by this exposure will provide the vignetting-corrected and quantum efficiency degradation-corrected count rate.

HB_Exposure
The effective exposure time, in seconds (s), for the hard-band, as derived from the standard-band exposure maps. Dividing the corresponding counts in this band by this exposure will provide the vignetting-corrected and quantum efficiency degradation-corrected count rate.

Band_Ratio_Limit
This parameter is a flag that is set to '<' if the band ratio is an upper limit, '>' if it is a lower limit, and '?' if both the hard band counts and soft band counts were upper limits.

Band_Ratio
The band ratio, defined as the ratio of the counts in the hard band to those in the soft band, HB/SB. Quoted band ratios have been corrected for differential vignetting between the hard band and the soft band using the appropriate exposure maps.

Band_Ratio_Pos_Err
The upper error in the band ratio, calculated following the "numerical method" described in in Section 1.7.3 of Lyons (1991, Data Analysis of Physical Science Students).

Band_Ratio_Neg_Err
The lower error in the band ratio, calculated following the "numerical method" described in in Section 1.7.3 of Lyons (1991, Data Analysis of Physical Science Students).

Photon_Index_Limit
This parameter is a flag that is set to '<' if the quoted photon index is an upper limit, or '>' if it is a lower limit.

Photon_Index
The effective photon index for a power-law model with the Galactic column density, as calculated from the band ratio when the number of source counts was not too low. When the number of counts is low, this parameter is poorly constrained and is set equal to 1.4, a representative value for faint sources that should give reasonable fluxes, for objects from Tables 2 and 3, the main and cross-field catalogs, respectively. For the faint X-ray sources from Table 6 (source_type = 'supplement'), a constant photon index of 2.0 was used, since the authors' source selection technique preferentially selected objects with 0.5-2.0 keV to R-band flux ratios < 0.1, which are observed to have effective photon indices of ~2.

Photon_Index_Pos_Err
The upper error in the photon index.

Photon_Index_Neg_Err
The lower error in the photon index.

FB_Flux_Limit
This parameter is a flag that is set to '<' if the quoted full-band flux is a lower limit.

FB_Flux
The observed-frame flux in the full band computed using the counts in this band, the appropriate exposure map, and the spectral slope given in the photon_index parameter, in erg/s/cm^2. The fluxes have not been corrected for absorption by the Galaxy or by material intrinsic to the source. Fow a power low model with a photon index of 1.4, the soft-band and hard-band Galactic absorption corrections are ~2.1% and ~0.1%, respectively.

SB_Flux_Limit
This parameter is a flag that is set to '<' if the quoted soft-band flux is a lower limit.

SB_Flux
The observed-frame flux in the soft band computed using the counts in this band, the appropriate exposure map, and the spectral slope given in the photon_index parameter, in erg/s/cm^2. The fluxes have not been corrected for absorption by the Galaxy or by material intrinsic to the source. Fow a power low model with a photon index of 1.4, the soft-band and hard-band Galactic absorption corrections are ~2.1% and ~0.1%, respectively.

HB_Flux_Limit
This parameter is a flag that is set to '<' if the quoted hard-band flux is a lower limit.

HB_Flux
The observed-frame flux in the hard band computed using the counts in this band, the appropriate exposure map, and the spectral slope given in the photon_index parameter, in erg/s/cm^2. The fluxes have not been corrected for absorption by the Galaxy or by material intrinsic to the source. Fow a power low model with a photon index of 1.4, the soft-band and hard-band Galactic absorption corrections are ~2.1% and ~0.1%, respectively.

ECDFS_Field
The observational (E-CDF-S) field number corresponding to the detected source. For the 14 sources that were detected in more than one observational field, the field in which the source had the greatest number of full-band counts is listed here.

Log_Min_FP_Prob
The logarithm of the minimum false-positive probability run with wavdetect in which each source was detected. A lower false-positive probability indicates a more significant source detection. Note that 655 (~86%) and 596 (~78%) of the sources were detected with false-positive probabilities thresholds of 1 x 10^-7 and 1 x 10^-8, respectively.

Notes
This parameter contains coded notes on the sources as follows:

      D = a source detected in more than one of the four observational fields.
      U = object lying in the UDF (see Figure 2 of the published paper).
      G = object that was identified as a Galactic star through the optical
          spectrophotometric COMBO-17 survey (Wolf et al. 2004, A&A, 421, 913).
      O = object that has a large cross-band (i.e., between the three standard
          bands) positional offsets (>2''); all of these sources lie at
          off-axis angles of >8'.
      M = source where the photometry was performed manually.
      S = close-double or close-triple source where manual separation was
          required.
      C = source detected within the boundary of the ~1 Ms CDF-S exposure that
          has no A03 or G02 counterpart.  Several of these sources are located
          in low-sensitivity regions of the ~1 Ms CDF-S, and a few of these
          sources may be variable.  For further explanation of many of these
  	notes, see the text in section 3.3.2 of the published paper.
      L = Object from the supplementary optical bright catalog where the X-ray
          source lies > 1.3'' from the centroid but is still within the extent
          of the optical emission.
  

Contact Person

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

Page Author: Browse Software Development Team
Last Modified: 25-Jan-2006