Chandra Large-Area Synoptic X-Ray Survey of Lockman Hole-NW Chan/Syn/LHN ivo://nasa.heasarc/clasxs NASA/GSFC HEASARC Yang et al.; Steffen et al. 2026-10-09 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source This table contains the X-ray catalog and basic results from the wide-area, moderately deep Chandra Large Area Synoptic X-ray Survey (CLASXS) of the Lockman Hole-Northwest (LHNW) field (Yang et al. 2004), as well as the results from optical and near-infrared photometric and spectroscopic observations of these X-ray sources (Steffen et al. 2004). The nine ACIS-I fields cover a contiguous solid angle of 0.4 square degrees and reach fluxes of 5 x 10&lt;sup&gt;-16&lt;/sup&gt; ergs/cm&lt;sup&gt;2&lt;/sup&gt;/s (0.4 - 2 keV) and 3 x 10&lt;sup&gt;-15&lt;/sup&gt; ergs/cm&lt;sup&gt;2&lt;/sup&gt;/s (2 - 8 keV). (Note that fields LHNW 1-3 were observed during 2001 April 30-May 17, and that the rest of the fields were observed during 2002 April 29-May 4). This survey bridges the gap between ultra-deep pencil-beam surveys, such as the Chandra Deep Fields (CDFs), and shallower, large-area surveys, allowing a better probe of the X-ray sources that contribute most of the 2 - 10 keV cosmic X-ray background (CXB). A total of 525 X-ray point sources and four extended sources were found. There are B, V, R, I, and z&#39; photometry for 521 (99%) of the 525 sources in the X-ray catalog and spectroscopic redshifts for 271 (52%), including 20 stars. The authors did not find evidence for redshift groupings of the X-ray sources, like those found in the Chandra Deep Field surveys, because of the larger solid angle covered by this survey. They separated the X-ray sources by optical spectral type and examined the colors, apparent and absolute magnitudes, and redshift distributions for the broad-line and non-broad-line active galactic nuclei. Combining their wide-area survey with other Chandra and XMM-Newton hard X-ray surveys, they find a definite lack of luminous, high accretion rate sources at z &lt; 1, consistent with previous observations that showed that super-massive black hole growth is dominated at low redshifts by sources with low accretion rates. This table was created by the HEASARC in May 2005 from the merger of 3 CDS tables, corresponding to Tables 2 and 3 from Yang et al. 2005 and Table 1 of Steffen et al. (2005): &lt;p&gt; &lt;pre&gt; J/AJ/128/1501/table2.dat J/AJ/128/1501/table3.dat J/AJ/128/1483/table1.dat &lt;/pre&gt; This is a service provided by NASA HEASARC . 2004AJ....128.1501Y https://heasarc.gsfc.nasa.gov/W3Browse/all/clasxs.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=clasxs& GET text/xml 180 99999 true 158.53845833 57.30661111 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=clasxs GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_clasxs&Action=More+Options&Action=Parameter+Search&ConeAdd=1 CHANDRA 0.0166666666666667 X-ray public clasxs Chandra Large-Area Synoptic X-Ray Survey of Lockman Hole-NW name Source Designation meta.id;meta.main char nullable ra Right Ascension degree pos.eq.ra;meta.main double nullable dec Declination degree pos.eq.dec;meta.main double nullable fb_flux Full Band (0.4-8.0keV) Flux (erg/s/cm^2) erg/s/cm^2 double nullable fb_flux_pos_err Upper 1-Sigma Poisson Error on Full Band Flux erg/s/cm^2 double nullable fb_flux_neg_err Lower 1-Sigma Poisson Error on Full Band Flux erg/s/cm^2 double nullable limit_rc_mag Flag Indicates Rc Magnitude Limit char nullable rc_mag Aperture-Corrected Cousins R-Band AB Magnitude mag double nullable redshift Spectroscopic Redshift src.redshift double nullable ra_optical Optical Right Ascension (J2000 Sexagesimal) char nullable limit_vmag Flag Indicates V Magnitude Limit char nullable hardness_ratio Hardness Ratio phot.flux;arith.ratio;em.X-ray.medium;em.X-ray.soft double nullable zd_mag Aperture-Corrected Sloan z-prime-Band AB Magnitude mag double nullable sb_counts_pos_err Upper 1-Sigma Poisson Error on Soft Band Counts ct double nullable hb_exposure Effective 2.0-8.0keV Band Exposure Time (s) s double nullable fb_counts_neg_err Upper 1-Sigma Poisson Error on Full Band Counts ct double nullable lii Galactic Longitude degree pos.galactic.lon double nullable ic_mag Aperture-Corrected Cousins I-Band AB Magnitude mag double nullable sb_flux_neg_err Lower 1-Sigma Poisson Error on Soft Band Flux erg/s/cm^2 double nullable limit_hb_counts Flag Indicates Limit on Hard Band Counts char nullable sb_counts_neg_err Lower 1-Sigma Poisson Error on Soft Band Counts ct double nullable hb_counts Net Hard Band (2.0-8.0keV) Counts ct double nullable dec_optical Optical Declination (J2000 Sexagesimal) char nullable sb_flux Soft Band (0.4-2.0keV) Flux (erg/s/cm^2) erg/s/cm^2 double nullable limit_hb_flux Flag Indicates Hard Band Flux Limit char nullable best_field_num LHNW Field Number Where the Source Has the Largest Effective Area short nullable limit_fb_flux Flag Indicates Full Band Flux Limit char nullable hb_flux Hard Band (2.0-8.0keV) Flux (erg/s/cm^2) erg/s/cm^2 double nullable off_axis_angle Smallest Aim-Point Distance (arcmin) arcmin double nullable limit_ic_mag Flag Indicates Ic Magnitude Limit char nullable bii Galactic Latitude degree pos.galactic.lat double nullable limit_hardness_ratio Flag Indicates Hardness Ratio Limit char nullable fb_counts_pos_err Upper 1-Sigma Poisson Error on Full Band Counts ct double nullable redshift_flag Spectroscopic Redshift Flag short nullable bmag Aperture-Corrected Johnson B-Band AB Magnitude mag phot.mag;em.opt.B double nullable hb_counts_neg_err Upper 1-Sigma Poisson Error on Hard Band Counts ct double nullable vmag Aperture-Corrected Johnson V-Band AB Magnitude mag phot.mag;em.opt.V double nullable sb_counts Net Soft Band (0.4-2.0keV) Counts ct double nullable num_fields_det LHNW Field Detection Numbers short nullable limit_zd_mag Flag Indicates z-prime Magnitude Limit char nullable sb_exposure Effective 0.4-2.0keV Band Exposure Time (s) s double nullable limit_sb_counts Flag Indicates Limit on Soft Band Counts char nullable limit_sb_flux Flag Indicates Soft Band Flux Limit char nullable ra_error Statistical Uncertainty in Right Ascension arcsec stat.error;pos.eq.ra;meta.main double nullable fb_exposure Effective 0.4-8.0keV Band Exposure Time (s) s double nullable sb2_flux Soft (0.5-2keV) X-Ray Flux (erg/s/cm^2) erg/s/cm^2 double nullable fb_counts Net Full Band (0.4-8.0keV) Counts ct double nullable limit_fb_counts Flag Indicates Limit on Full Band Counts char nullable alt_name Alternative Source Designation meta.id char nullable source_number The Yang et al. (2004, Cat. <J/AJ/128/1501>) Unique Catalog Source Number meta.id short nullable hb_flux_pos_err Upper 1-Sigma Poisson Error on Hard Band Flux erg/s/cm^2 double nullable limit_bmag Flag Indicates B Magnitude Limit char nullable hb_counts_pos_err Upper 1-Sigma Poisson Error on Hard Band Counts ct double nullable dec_error Statistical Uncertainty in Declination arcsec stat.error;pos.eq.dec;meta.main double nullable sb_flux_pos_err Upper 1-Sigma Poisson Error on Soft Band Flux erg/s/cm^2 double nullable hb_flux_neg_err Lower 1-Sigma Poisson Error on Hard Band Flux erg/s/cm^2 double nullable "__x_ra_dec" System unit vector column double nullable "__y_ra_dec" System unit vector column double nullable "__z_ra_dec" System unit vector column double nullable "__row" System index column char nullable