ORIONFFCXO ivo://nasa.heasarc/orionffcxo NASA/GSFC HEASARC Ramirez et al. 2026-10-09 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source This table contains the results of Chandra observations of two flanking fields (FFs) in Orion outside the Orion Nebula Cluster (ONC), in the form of a catalog of 417 sources, which includes X-ray luminosity, optical and infrared photometry, and X-ray variability information. 91 variable sources were found, 33 of which have flarelike light curves, and 11 of which have a pattern of a steady increase or decrease over a 10 hour period. The optical and infrared photometry for the stars identified as X-ray sources are consistent with most of these objects being pre-main-sequence stars with ages younger than 10 Myr. The two flanking fields in Orion were observed with the Advanced CCD Imaging Spectrometer (ACIS) detector on board the Chandra X-Ray Observatory. The north Orion flanking field (NOFF) is centered at a J2000 RA and Declination of 05:35:19, -04:48:15, which is about 36' (~5 pc, at a distance of 470 pc) north of the Trapezium cluster and was observed on 2002 August 26 with a total exposure time of 48.8 ks. The south Orion flanking field (SOFF), centered at a J2000 RA and Declination of 05:35:06, -05:40:48, which is about 17' (~ 2.5pc, at a distance of 470 pc) south of the Trapezium cluster, was observed on 2002 September 6 with a total exposure time of 47.9 ks. The data analysis for these observations was performed in the same manner as described in Ramirez et al. (2004, AJ, 127, 2659) for a similar observation of a field in NGC 2264, which should be consulted for the full details. (See also the help file for the HEASARC version of the catalog from the latter reference available at /W3Browse/chandra/ngc2264cxo.html ). This table was created by the HEASARC in February 2007 based on the CDS table J/AJ/128/787, files table1.dat, table3.dat and table4.dat. It does not include the results from the spectral analysis of 44 bright X-ray sources which were presented in Table 2 of the reference paper. This is a service provided by NASA HEASARC . 2004AJ....128..787R https://heasarc.gsfc.nasa.gov/W3Browse/all/orionffcxo.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=orionffcxo& GET text/xml 180 99999 true 83.75225 -5.81649778 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=orionffcxo GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_orionffcxo&Action=More+Options&Action=Parameter+Search&ConeAdd=1 CHANDRA 0.0166666666666667 X-ray Optical Infrared public orionffcxo Orion Flanking Fields Chandra X-Ray Point Source Catalog name Chandra Object 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 ctrpart_name Object Counterpart Designation char nullable vmag V-Band Magnitude mag phot.mag;em.opt.V double nullable count_rate Count Rate (ct/s) ct/s phot.count;em.X-ray double nullable flux X-Ray Flux (erg/s/cm^2) erg/s/cm^2 phot.flux;em.X-ray double nullable log_lx Logarithm of the X-Ray Luminosity (in erg/s) log(erg/s) 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 alt_name_2 Rebull Catalog Designation meta.id char nullable alt_name_3 Carpenter Catalog Designation meta.id char nullable bii Galactic Latitude degree pos.galactic.lat double nullable dec_ctrpart Declination of Counterpart (J2000) char nullable exposure Effective Exposure Time (s) s time.duration;obs.exposure double nullable hmag H-Band Magnitude mag double nullable prob_constant Probability of the Light Curve Being Constant percent short nullable kmag K-Band Magnitude mag double nullable alt_name_4 2MASS Name (JHHMMSSss+DDMMSSs) meta.id char nullable lii Galactic Longitude degree pos.galactic.lon double nullable field_name Orion Flanking Field char nullable source_number X-Ray Source Identification Number meta.id char nullable other_names Other Designations char nullable ic_mag Ic-Band Magnitude mag double nullable extraction_radius Count Extraction Radius (arcsec) arcsec double nullable jmag J-Band Magnitude mag double nullable ra_ctrpart Right Ascension of Counterpart (J2000) char nullable comment_flags Flags Indicate Additional Comments char nullable alt_name_1 Parenago Catalog Designation meta.id char nullable off_axis Off-Axis Angle (arcmin) arcmin instr.offset double nullable alt_name Alternate Object Designation meta.id char nullable psf_fraction Fraction of the Point-Spread Function double nullable