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NUSTARSSC2 - NuSTAR Serendipitous Survey 40-Month Secondary Source Catalog

HEASARC
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Overview

This table contains some of the science results from the Nuclear Spectroscopic Telescope Array (NuSTAR) Serendipitous Survey. The catalog incorporates data taken during the first 40 months of NuSTAR operation, which provide ~20 Ms of effective exposure time over 331 fields, with an areal coverage of 13 deg2. The primary catalog (available as the HEASARC NUSTARSSC table) contains 498 sources (the abstract of the reference paper states that there are 497 sources) detected in total over the 3-24 keV energy range. There are 276 sources with spectroscopic redshifts and classifications, largely resulting from the authors' extensive campaign of ground-based spectroscopic follow-up. The authors characterize the overall sample in terms of the X-ray, optical, and infrared source properties. The sample is primarily composed of active galactic nuclei (AGN), detected over a large range in redshift from z = 0.002 to 3.4 (median redshift z of 0.56), but also includes 16 spectroscopically confirmed Galactic sources. There is a large range in X-ray flux, from log (f_3-24_keV) ~ -14 to -11 (in units of erg s-1 cm-2), and in rest-frame 10-40 keV luminosity, from log (L10-40keV) ~ 39 to 46 (in units of erg s-1), with a median of 44.1. Approximately 79% of the NuSTAR sources have lower-energy (<10 keV) X-ray counterparts from XMM-Newton, Chandra, and Swift XRT observations. The mid-infrared (MIR) analysis, using WISE all-sky survey data, shows that MIR AGN color selections miss a large fraction of the NuSTAR-selected AGN population, from ~15% at the highest luminosities (LX > 1044 erg s-1) to ~80% at the lowest luminosities (LX < 1043 erg s-1). The authors' optical spectroscopic analysis finds that the observed fraction of optically obscured AGN (i.e., the type 2 fraction) is FType2 = 53 (+14, -15) per cent, for a well-defined subset of the 8-24 keV selected sample. This is higher, albeit at a low significance level, than the type 2 fraction measured for redshift- and luminosity-matched AGNs selected by < 10 keV X-ray missions.

This table contains the Secondary NuSTAR Serendipitous Source Catalog of 64 sources found using wavdetect to search for significant emission peaks in the FPMA and FPMB data separately (see Section 2.1.1 of Alexander et al. 2013, ApJ, 773, 125) and in the combined A+B data. These sources are listed in Table 7 of the reference paper. This method was developed alongside the primary one (Section 2.3 of the reference paper) in order to investigate the optimum source detection methodologies for NuSTAR and to identify sources in regions of the NuSTAR coverage that are automatically excluded in the primary source detection. The authors emphasize that these secondary sources are not used in any of the science analyses presented in their paper. Nevertheless, these secondary sources are robust NuSTAR detections, some of which will be incorporated in future NuSTAR studies, and for many of them (35 out of the 43 sources with spectroscopic identifications) the authors have obtained new spectroscopic redshifts and classifications through their follow-up program. The X-ray photometric parameters for 4 sources are left blank as in these cases the A+B data prohibit reliable photometric constraints. Additional information on these Secondary Catalog sources that the authors obtained using optical spectroscopy is available in Table 8 of the reference paper (q.v.).

This table does NOT contain the the 498 sources in the Primary NuSTAR Serendipitous Source Catalog that were found using the source detection procedure described in Section 2.3 of the reference paper, and that are listed in Table 5 (op. cit.).


Catalog Bibcode

2017ApJ...836...99L

References

The NuSTAR Serendipitous Survey: the 40 Month Catalog and the Properties of
the Distant High Energy X-ray Source Population.
      Lansbury G.B., Stern D., Aird J., Alexander D.M., Fuentes C.,
      Harrison F.A., Treister E., Bauer F.E., Tomsick J.A., Balokovic M.,
      Del Moro A., Gandhi P., Ajello M., Annuar A., Ballantyne D.R.,
      Boggs S.E., Brandt W.N., Brightman M., Chen C.-T.J., Christensen F.E.,
      Civano F., Comastri A., Craig W.W., Forster K., Grefenstette B.W.,
      Hailey C.J., Hickox R.C., Jiang B., Jun H.D., Koss M., Marchesi S.,
      Melo A.D., Mullaney J.R., Noirot G., Schulze S., Walton D.J.,
      Zappacosta L., Zhang W.W.
     <Astrophys. J. 836, 99 (2017)>
     =2017ApJ...836...99L        (SIMBAD/NED BibCode)

Provenance

This table was created by the HEASARC in July 2017 based on the machine-readable version of Table 7 from the reference paper, the Secondary NuSTAR Serendipitous Source Catalog, that was obtained from the ApJ web site.

Parameters

Source_Number
A sequential identification number from 1 to 64 for each NuSTAR X-ray source in the Secondary Catalog, sorted in order of increasing J2000.0 Right Ascension. Notice that the 498 sources in the Primary NuSTAR Serendipitous Source Catalog are numbered from 1 to 498, so, when referring to a source in this present catalog, the HEASARC suggests using a prefix of 'S' as a unique descriptor.

Name
The NuSTAR J2000.0 position-based source designation, viz., 'NuSTAR JHHMMSS+DDMM.m', as registered with the Dictionary of Nomenclature of Celestial Objects.

RA
The Right Ascension of the NuSTAR source in the selected equinox. This was given in J2000.0 decimal degree coordinates to a precision of 10-6 degrees in the original table.

Dec
The Declination of the NuSTAR source in the selected equinox. This was given in J2000.0 decimal degree coordinates to a precision of 10-6 degrees in the original table.

LII
The Galactic Longitude of the NuSTAR source.

BII
The Galactic Latitude of the NuSTAR source.

SB_Counts
The soft-band (3-8 keV) total counts in the source (i.e., all counts within the source aperture). This photometric quantity is calculated at the indicated source coordinates using a source aperture of 30 arcseconds radius (see Section 2.4 of the reference paper). The value is non-aperture-corrected, i.e., it corresponds to the 30-arcsecond value, and has not been corrected to the full PSF values.

SB_Bck_Counts
The estimated number of background counts in the soft band scaled to the source aperture.

SB_Net_Counts
The net (background-subtracted) soft-band (3-8 keV) counts in the source. This photometric quantity is calculated at the indicated source coordinates using a source aperture of 30 arcseconds radius (see Section 2.4 of the reference paper). The value is non-aperture-corrected, i.e., it corresponds to the 30-arcsecond value, and has not been corrected to the full PSF values. For sources not detected in this band (indicated by having a value of -99.000 for the associated error parameter), the quoted value corresponds to the 90% confidence level upper limit.

SB_Net_Counts_Error
The uncertainty in the net soft-band (3-8 keV) source counts. If the corresponding counts quantity is an upper limit rather than a detection, this error is set to -99.000.

HB_Counts
The hard-band (8-24 keV) total counts in the source (i.e., all counts within the source aperture). This photometric quantity is calculated at the indicated source coordinates using a source aperture of 30 arcseconds radius (see Section 2.4 of the reference paper). The value is non-aperture-corrected , i.e., it correspond to the 30-arcsecond value, and has not been corrected to the full PSF values.

HB_Bck_Counts
The estimated number of background counts in the hard band scaled to the source aperture.

HB_Net_Counts
The net (background-subtracted) hard-band (8-24 keV) counts in the source. This photometric quantity is calculated at the indicated source coordinates using a source aperture of 30 arcseconds radius (see Section 2.4 of the reference paper). The value is non-aperture-corrected, i.e., it corresponds to the 30-arcsecond value, and has not been corrected to the full PSF values. For sources not detected in this band (indicated by having a value of -99.000 for the associated error parameter), the quoted value corresponds to the 90% confidence level upper limit.

HB_Net_Counts_Error
The uncertainty in the net hard-band (8-24 keV) source counts. If the corresponding counts quantity is an upper limit rather than a detection, this error is set to -99.000.

FB_Counts
The full-band (3-24 keV) total counts in the source (i.e., all counts within the source aperture). This photometric quantity is calculated at the indicated source coordinates using a source aperture of 30 arcseconds radius (see Section 2.4 of the reference paper). The value is non-aperture-corrected , i.e., it correspond to the 30-arcsecond value, and has not been corrected to the full PSF values.

FB_Bck_Counts
The estimated number of background counts in the full band scaled to the source aperture.

FB_Net_Counts
The net (background-subtracted) full-band (3-24 keV) counts in the source. This photometric quantity is calculated at the indicated source coordinates using a source aperture of 30 arcseconds radius (see Section 2.4 of the reference paper). The value is non-aperture-corrected , i.e., it correspond to the 30-arcsecond value, and has not been corrected to the full PSF values. For sources not detected in this band (indicated by having a value of -99.000 for the associated error parameter), the quoted value corresponds to the 90% confidence level upper limit.

FB_Net_Counts_Error
The uncertainty in the net full-band (3-24 keV) source counts. If the corresponding counts quantity is an upper limit rather than a detection, this error is set to -99.000.

SB_Exposure
The average net, vignetting-corrected exposure time, in seconds, at the source coordinates, for the soft energy band. These correspond to the A+B data, so that they should be divided by 2 to obtain the average exposure per FPM.

HB_Exposure
The average net, vignetting-corrected exposure time, in seconds, at the source coordinates, for the hard energy band. These correspond to the A+B data, so that they should be divided by 2 to obtain the average exposure per FPM.

FB_Exposure
The average net, vignetting-corrected exposure time, in seconds, at the source coordinates, for the full energy band. These correspond to the A+B data, so that they should be divided by 2 to obtain the average exposure per FPM.

SB_Net_Rate
The aperture-corrected total count rate of the source in the soft band as determined from the corresponding photometric counts (sb_counts), estimated background counts (sb_bck_counts), and exposure time (sb_exposure), in ct/s.

SB_Net_Rate_Error
The uncertainty in the aperture-corrected total count rate of the source in the soft band, in ct/s. If the corresponding count rate is an upper limit rather than a detection, this error is set to -99.000.

HB_Net_Rate
The aperture-corrected total count rate of the source in the hard band as determined from the corresponding photometric counts (hb_counts), estimated background counts (hb_bck_counts), and exposure time (hb_exposure), in ct/s.

HB_Net_Rate_Error
The uncertainty in the aperture-corrected total count rate of the source in the hard band, in ct/s. If the corresponding count rate is an upper limit rather than a detection, this error is set to -99.000.

FB_Net_Rate
The aperture-corrected total count rate of the source in the full band as determined from the corresponding photometric counts (fb_counts), estimated background counts (fb_bck_counts), and exposure time (fb_exposure), in ct/s.

FB_Net_Rate_Error
The uncertainty in the aperture-corrected total count rate of the source in the full band, in ct/s. If the corresponding count rate is an upper limit rather than a detection, this error is set to -99.000.

SB_Flux
The observed-frame flux of the source in the soft band, after deblending has been performed, in erg s-1 cm-2. To measure fluxes, the authors convert from the deblended 30" soft-band count rates using the conversion factor of 6.7 x 10-11 erg cm-2 s-1. This conversion factor was derived to account for the NuSTAR response, and assumes an unabsorbed power law with a photon index of Gammaeff = 1.8 (typical of AGN detected by NuSTAR; e.g., Alexander et al. 2013, ApJ, 773, 125). The conversion factor returns the aperture-corrected flux, i.e., it is corrected to the 100% encircled-energy fraction of the PSF.

SB_Flux_Error
The 84% confidence level uncertainty in the observed-frame flux of the source in the soft band, after deblending has been performed, in erg s-1 cm-2. If the corresponding flux is an upper limit rather than a detection, this error is set to -99.000.

HB_Flux
The observed-frame flux of the source in the hard band, after deblending has been performed, in erg s-1 cm-2. To measure fluxes, the authors convert from the deblended 30" hard-band count rates using the conversion factor of 13.9 x 10-11 erg cm-2 s-1. This conversion factor was derived to account for the NuSTAR response, and assumes an unabsorbed power law with a photon index of Gammaeff = 1.8 (typical of AGN detected by NuSTAR; e.g., Alexander et al. 2013, ApJ, 773, 125). The conversion factor returns the aperture-corrected flux, i.e., it is corrected to the 100% encircled-energy fraction of the PSF.

HB_Flux_Error
The 84% confidence level uncertainty in the observed-frame flux of the source in the hard band, after deblending has been performed, in erg s-1 cm-2. If the corresponding flux is an upper limit rather than a detection, this error is set to -99.000.

FB_Flux
The observed-frame flux of the source in the full band, after deblending has been performed, in erg s-1 cm-2. To measure fluxes, the authors convert from the deblended 30" full-band count rates using the conversion factor of 9.4 x 10-11 erg cm-2 s-1. This conversion factor was derived to account for the NuSTAR response, and assumes an unabsorbed power law with a photon index of Gammaeff = 1.8 (typical of AGN detected by NuSTAR; e.g., Alexander et al. 2013, ApJ, 773, 125). The conversion factor returns the aperture-corrected flux, i.e., it is corrected to the 100% encircled-energy fraction of the PSF.

FB_Flux_Error
The 84% confidence level uncertainty in the observed-frame flux of the source in the full band, after deblending has been performed, in erg s-1 cm-2. If the corresponding flux is an upper limit rather than a detection, this error is set to -99.000.

Softxray_Ctrpart_Orig
The name of the observatory or instrument which detected the lower-energy (<10 keV) X-ray counterpart of the NuSTAR source: CXO, XMM or (Swift) XRT. (See Section 3.1 of the reference paper for details of the soft X-ray counterpart matching procedure).

Softxray_Ctrpart_RA
The Right Ascension of the soft X-ray counterpart in the selected equinox. This was given in J2000 decimal degree coordinates to a precision of 10-6 degrees in the original table.

Softxray_Ctrpart_Dec
The Declination of the soft X-ray counterpart in the selected equinox. This was given in J2000 decimal degree coordinates to a precision of 10-6 degrees in the original table.

Opt_Ctrpart_Orig
An abbreviated code indicating the origin of the adopted optical or other wavelength counterpart, as follows (see Section 3.2 of the reference paper for details of the optical counterpart matching procedure):

   Code      Reference

   SDSS      Sources with soft X-ray counterparts and successful matches in
             the SDSS DR7 catalog (York et al. 2000, AJ, 120, 1579);
   USNO      Sources with soft X-ray counterparts and successful
             matches in the USNOB1 catalog (Monet et al. 2003, AJ, 125, 948);
   MAN       Sources with a soft X-ray counterpart and a corresponding optical
             counterpart manually identified in the available optical coverage.
   WISE      Sources with a WISE infrared counterpart.
  

Opt_RA
The Right Ascension of the optical or other wavelength counterpart in the selected equinox. This was given in J2000 decimal degree coordinates to a precision of 10-6 degrees in the original table.

Opt_Dec
The Declination of the optical or other wavelength counterpart in the selected equinox. This was given in J2000 decimal degree coordinates to a precision of 10-6 degrees in the original table.

Redshift
The spectroscopic redshift of the NuSTAR source. The large majority of the redshifts were obtained through the authors' own campaign of ground-based spectroscopic follow-up of NuSTAR serendipitous survey sources (see Section 3.3.1 of the reference paper).

RF_Hardxray_Luminosity
The rest-frame 10-40 keV luminosity of the NuSTAR source, in erg s-1, estimated from the quoted X-ray fluxes, following the procedure outlined in Section 2.4 of the reference paper. Negative luminosity values indicate upper limits. The luminosities are observed values, uncorrected for any absorption along the line of sight. The intrinsic luminosities may therefore be higher, for highly absorbed AGN.

Primary_Exclude_Code
A character code indicating the reason for the source not being included in the Primary Catalog. These reasons are categorized into four groups: (1) 'E' means that the source is within or very close to the peripheral region of the NuSTAR mosaic, which is excluded from the primary source detection (33% of cases); (2) 'T' that the source is narrowly offset from the central science target position for the NuSTAR observation (and thus automatically excluded; see Section 2.3 of the reference paper), or from another bright source in the field (11%); (3) 'X' that the source lies in a region which is masked out, or is in a NuSTAR field which is excluded, from the primary source detection (44%), e.g., due to highly contaminating stray light or a bright science target; or (4) 'L' that the source has a comparatively low detection significance (12%).


Contact Person

Questions regarding the NUSTARSSC2 database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 12-Jul-2017