LALACETCXO ivo://nasa.heasarc/lalacetcxo NASA/GSFC HEASARC Wang et al. 2026-10-09 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source The 174 ks Chandra Advanced CCD Imaging Spectrometer (ACIS) exposure of the Large Area Lyman Alpha Survey (LALA) Cetus field is the second of the two deep Chandra images on LALA fields. In their paper, the authors present the Chandra X-ray sources detected in the Cetus field, along with an analysis of X-ray source counts, the stacked X-ray spectrum, and the optical identifications. A total of 188 X-ray sources were detected: 174 in the 0.5-7.0 keV band, 154 in the 0.5-2.0 keV band, and 113 in the 2.0-7.0 keV band. The X-ray source counts were derived and compared with the 172 ks exposure LALA Bootes field (available as the LALABOOCXO table in Browse). Interestingly, the authors find consistent hard-band X-ray source density, but a (36 +/- 12)% higher soft-band X-ray source density in the Cetus field. The weighted stacked spectrum of the detected X-ray sources can be fitted by a power law with photon index Gamma = 1.55. Based on the weighted stacked spectrum, the authors find that the resolved fraction of the X-ray background drops from (72 +/- 1)% at 0.5-1.0 keV to (63 +/- 4)% at 6.0-8.0 keV. The unresolved spectrum can be fitted by a power law over the range 0.5-7 keV, with a photon index Gamma = 1.22. Optical counterparts are also presented for 154 of the X-ray sources, down to a limiting magnitude of r' = 25.9 (Vega), using a deep r'-band image obtained with the MMT. This table was created by the HEASARC in October 2010 based on the CDS table J/ApJ/669/765 file table1.dat This is a service provided by NASA HEASARC . 2007ApJ...669..765W https://heasarc.gsfc.nasa.gov/W3Browse/all/lalacetcxo.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=lalacetcxo& GET text/xml 180 99999 true 31.14125 -5.26230556 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=lalacetcxo GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_lalacetcxo&Action=More+Options&Action=Parameter+Search&ConeAdd=1 CHANDRA 0.0166666666666667 Optical X-ray public lalacetcxo LALA Cetus Field Chandra X-Ray Point Source Catalog source_number Sequential Identification Number for Each Source in Catalog meta.id;src short nullable name Source Designation (CXOLALA2 JHHMMSS.s+DDMMSS.s) 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 error_radius 3-Sigma Uncertainties of Centroid Position as Given by WAVDETECT arcsec stat.error;pos double nullable fb_counts Total Band (0.5-10keV) Net Counts ct phot;em.X-ray double nullable fb_counts_pos_err Upper Error on Total Band (0.5-10keV) Net Counts ct stat.error;phot;em.X-ray double nullable fb_counts_neg_err Lower Error on Total Band (0.5-10keV) Net Counts ct stat.error;phot;em.X-ray double nullable rmag_limit Limit Flag for r-prime Band Magnitude meta.code;phot.mag;em.opt.R char nullable rmag r-prime Band Magnitude from AUTO SExtractor mag phot.mag;em.opt.R double nullable rmag_error RMS Uncertainty on r-prime Band Magnitude mag stat.error;phot.mag;em.opt.R double nullable rmag_flag Note for r-prime Band Magnitude meta.note;phot.mag;em.opt.R char nullable sb_flux Flux Density in Soft Band (0.5-2keV) erg/s/cm^2 phot.flux;em.X-ray.soft double nullable hardness_ratio_neg_err Lower Error on Hardness Ratio stat.error;phot.flux;arith.ratio;em.X-ray double nullable sb_flux_limit Limit Flag for Flux Density in Soft Band (0.5-2keV) meta.code;phot.flux;em.X-ray.soft char nullable hb_counts_pos_err Upper Error on Hard Band (2-10keV) Net Counts ct stat.error;phot;em.X-ray.medium double nullable fb_flux Flux Density in Total Band (0.5-10keV) erg/s/cm^2 phot.flux;em.X-ray double nullable hb_flux_limit Limit Flag for Flux Density in Hard Band (2-10keV) meta.code;phot.flux;em.X-ray.medium char nullable lii Galactic Longitude degree pos.galactic.lon double nullable ra_offset Offset in Right Ascension of the Detected Optical Counterpart arcsec pos.angDistance double nullable detection_bands Flag [TSH] Indicates Band Detections meta.code;instr.bandpass char nullable sb_counts_neg_err Lower Error on Soft Band (0.5-2keV) Net Counts ct stat.error;phot;em.X-ray.soft double nullable bii Galactic Latitude degree pos.galactic.lat double nullable hb_counts Hard Band (2-10keV) Net Counts ct phot;em.X-ray.medium double nullable source_flag Flag [X] Indicates Multiplicity Index meta.code.multip char nullable hardness_ratio_pos_err Upper Error on Hardness Ratio stat.error;phot.flux;arith.ratio;em.X-ray double nullable hb_flux Flux Density in Hard Band (2-10keV) erg/s/cm^2 phot.flux;em.X-ray.medium double nullable sb_counts_pos_err Upper Error on Soft Band (0.5-2keV) Net Counts ct stat.error;phot;em.X-ray.soft double nullable dec_offset Offset in Declination of the Detected Optical Counterpart arcsec pos.angDistance double nullable sb_counts Soft Band (0.5-2keV) Net Counts ct phot;em.X-ray.soft double nullable hardness_ratio Hardness Ratio (H-S)/(H+S) phot.flux;arith.ratio;em.X-ray double nullable alt_name Alternative Catalog-Based Source Designation meta.id char nullable hb_counts_neg_err Lower Error on Hard Band (2-10keV) Net Counts ct stat.error;phot;em.X-ray.medium 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