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Last modified: 5 December 2017

Per-Observation Detections Table


Each identified distinct X-ray source on the sky is represented in the catalog by one or more "source observation" entries - one for each observation in which the source has been detected - and a single "master source" entry. The individual source entries record all of the properties about a detection extracted from a single observation, as well as associated file-based data products, which are observation-specific.

Note: Source properties in the catalog which have a value for each science energy band (type "double[6]", "long[6]", and "integer[6]" in the table below) have the corresponding letters appended to their names. For example, "flux_aper_b" and "flux_aper_h" represent the background-subtracted, aperture-corrected broad-band and hard-band energy fluxes, respectively.

Go to: Catalog Columns Index | Alphabetical List
Context Column Name Type Units Description
Observation Identification obsid integer Observation ID (ObsID)
obi integer Observation Interval (ObI)

Pointing Information targname string target name for the observation
ra_targ double deg ICRS right ascension of the target
dec_targ double deg ICRS declination of the target
ra_pnt double deg ICRS right ascension of the mean pointing
dec_pnt double deg ICRS declination of the mean pointing
roll_pnt double deg roll angle of the mean pointing
chipx_pnt double pixel chipx corresponding to (ra_pnt, dec_pnt)
chipy_pnt double pixel chipy corresponding to (ra_pnt, dec_pnt)
chip_id_pnt integer reference ACIS CCD or HRC segment for (chipx_pnt, chipy_pnt)
ra_nom double deg ICRS right ascension of the tangent point
dec_nom double deg ICRS declination of the tangent point
roll_nom double deg roll angle of the tangent point

Timing Information gti_start double s start time for the valid data in mission elapsed time
gti_stop double s stop time for the valid data in mission elapsed time
gti_elapse double s total elapsed time of the observation. The total elapsed time is not equal to the total exposure time of the observation because periods of bad time may have been filtered out.
gti_obs string (TT) start time for the valid data in FITS standard format (ISO 8601)
gti_end string (TT) stop time for the valid data in FITS standard format (ISO 8601)
gti_mjd_obs double MJD (TT) modified Julian date for the start time of the valid data
mjd_ref double MJD (TT) modified Julian date reference corresponding to zero seconds mission elapsed time

Observing Cycle ao integer Announcement of Opportunity (AO) number for the Chandra observing cycle in which the observation was scheduled

Instrument Configuration instrument string instrument used for the observation: ACIS or HRC
grating string grating used for the observation: NONE, HETG, or LETG
datamode string data mode used for the observation
readmode string readout mode used for the observation: TIMED or CONTINUOUS; ACIS only
cycle string cycle for alternating exposure (interleaved) mode observations: P (primary) or S (secondary); ACIS only. Value is P for full-frame observations.
exptime double CCD frame time; ACIS only
timing_mode boolean TRUE if the observation was done in precision timing mode, FALSE if not; HRC only

Aspect Information sim_x double mm mean sim_x position during observation
sim_z double mm mean sim_z position during observation
dy double mm mean dy position during observation
dz double mm mean dz position during observation
dtheta double deg mean dtheta position during observation
deltax double arcsec X translation update from fine astrometry applied to computed asol3 file
deltay double arcsec Y translation update from fine astrometry applied to computed asol3 file
deltarot double deg roll angle update from fine astrometry applied to computed asol3 file
dscale double deg scale factor update from fine astrometry applied to computed asol3 file
man_astrom_flag boolean fine astrometry transform computed manually

Processing Information ascdsver string software version used to create the Level 3 event file
caldbver string calibration database version used to create the Level 3 event file
crdate string creation date and time (UTC) of the Level 3 event file

Source Identification region_id integer source region within the observation

Position and Position Errors theta double arcmin PSF 90% ECF off-axis angle, θ, of the source
phi double deg PSF 90% ECF azimuthal angle, φ, of the source
chipx double pixel the chipx position corresponding to the off-axis angles (θ, φ) of the source
chipy double pixel the chipy position corresponding to the off-axis angles (θ, φ) of the source
chip_id integer reference ACIS CCD or HRC segment for (chipx, chipy)

Source Significance flux_significance double[6] significance of the single-observation detection determined from the ratio of the single-observation detection flux to the estimated error in the local background for each source detection energy band
likelihood double[6] significance of the single-observation detection computed by the single-observation detection algorithm from the maximum likelihood for each source detection energy band

Source Flags conf_code integer[6] indicates whether the source is in a confused region in any source detection energy band
dither_warning_flag boolean TRUE if the highest statistically significant peak in the power spectrum of the source region count rate for each science energy band occurs either at the dither frequency of the observation or at a beat frequency of the dither frequency. Otherwise, the value is FALSE.
edge_code coded byte indicates that the position or region dithered off a chip boundary
extent_code integer[6] indicates whether the source is extended in all science energy bands
multi_chip_code coded byte indicates that the position or region dithered over multiple chip boundaries
pileup_warning double counts/frame/pixel indicates that the source properties may be affected by ACIS pileup
sat_src_flag boolean indicates a saturated source (strong ACIS pileup)
streak_src_flag boolean indicates that the source lies on an ACIS readout streak
var_code coded byte indicates source variability in any science energy band

Source Extent and Errors mjr_axis_raw double[6] arcsec 1σ radius along the major axis of the rotated elliptical Gaussian parameterization of the raw extent of a source for each science energy band
mjr_axis_raw_lolim double[6] arcsec 68% error lower limit on the "mjr_axis_raw" value for each science energy band
mjr_axis_raw_hilim double[6] arcsec 68% error upper limit on the "mjr_axis_raw" value for each science energy band
mnr_axis_raw double[6] arcsec 1σ radius along the minor axis of the rotated elliptical Gaussian parameterization of the raw extent of a source for each science energy band
mnr_axis_raw_lolim double[6] arcsec 68% error lower limit on the "mnr_axis_raw" value for each science energy band
mnr_axis_raw_hilim double[6] arcsec 68% error upper limit on the "mnr_axis_raw" value for each science energy band
pos_angle_raw double[6] deg position angle of the rotated elliptical Gaussian parameterization of the raw extent of a source for each science energy band
pos_angle_raw_lolim double[6] deg 68% error lower limit on the "pos_angle_raw" value for each science energy band
pos_angle_raw_hilim double[6] deg 68% error upper limit on the "pos_angle_raw" value for each science energy band
psf_mjr_axis_raw double[6] arcsec 1σ major axis of the rotated elliptical Gaussian parameterization of the raw extent of the PSF for each science energy band
psf_mjr_axis_raw_lolim double[6] arcsec 68% error lower limit on the "psf_mjr_axis_raw" value for each science energy band
psf_mjr_axis_raw_hilim double[6] arcsec 68% error upper limit on the "psf_mjr_axis_raw" value for each science energy band
psf_mnr_axis_raw double[6] arcsec 1σ minor axis of the rotated elliptical Gaussian parameterization of the raw extent of the PSF for each science energy band
psf_mnr_axis_raw_lolim double[6] arcsec 68% error lower limit on the "psf_mnr_axis_raw" value for each science energy band
psf_mnr_axis_raw_hilim double[6] arcsec 68% error upper limit on the "psf_mnr_axis_raw" value for each science energy band
psf_pos_angle_raw double[6] deg position angle of the 1σ rotated elliptical Gaussian parameterization of the raw extent of the PSF for each science energy band
psf_pos_angle_raw_lolim double[6] deg 68% error upper limit on the "psf_pos_angle_raw" value for each science energy band
psf_pos_angle_raw_hilim double[6] deg 68% error upper limit on the "psf_pos_angle_raw" value for each science energy band
major_axis double[6] arcsec best estimate value for the 1σ radius along the major axis of the rotated elliptical Gaussian parameterization of the deconvolved source extent ellipse for each science energy band
major_axis_lolim double[6] arcsec 1σ major radius of deconvolved elliptical Gaussian source fit 68% lower limit for each science energy band
major_axis_hilim double[6] arcsec 1σ major radius of deconvolved elliptical Gaussian source fit 68% upper limit for each science energy band
minor_axis double[6] arcsec best estimate value for 1σ radius along the minor axis of the rotated elliptical Gaussian parameterization of the deconvolved source extent ellipse for each science energy band
minor_axis_lolim double[6] arcsec 1σ minor radius of deconvolved elliptical Gaussian source fit 68% lower limit for each science energy band
minor_axis_hilim[6] double arcsec 1σ minor radius of deconvolved elliptical Gaussian source fit 68% upper limit for each science energy band
pos_angle double[6] deg best estimate value for the position angle of the rotated elliptical Gaussian parameterization of the deconvolved source extent ellipse of "major_axis" for each science energy band
pos_angle_lolim double[6] deg position angle of "major_axis" 68% lower limit for each science energy band
pos_angle_hilim double[6] deg position angle of "major_axis" 68% upper limit for each science energy band
src_area double[6] sq. arcseconds Equivalent source extent area calculated from the "major_axis" and "minor_axis" for each science energy band

Aperture Photometry cnts_aper long[6] counts total counts measured in the modified source region for each science energy band
cnts_aperbkg long[6] counts total counts measured in the modified background region for each science energy band
src_cnts_aper double[6] counts net background-subtracted source counts inferred from the modified source region for each science energy band
src_cnts_aper_lolim double[6] counts net background-subtracted source counts inferred from the modified source region 68% lower limit for each science energy band
src_cnts_aper_hilim double[6] counts net background-subtracted source counts inferred from the modified source region 68% upper limit for each science energy band
src_rate_aper double[6] counts s-1 background-subtracted source count rate inferred from the modified source region for each science energy band
src_rate_aper_lolim double[6] counts s-1 lower limit on the 68% confidence interval of the "src_rate_aper" value for each science energy band
src_rate_aper_hilim double[6] counts s-1 upper limit on the 68% confidence interval of the "src_rate_aper" value for each science energy band
photflux_aper double[6] photons s-1 cm-2 background-subtracted flux inferred from the modified source region for each science energy band
photflux_aper_lolim double[6] photons s-1 cm-2 lower limit on the 68% confidence interval of the "photflux_aper" value for each science energy band
photflux_aper_hilim double[6] photons s-1 cm-2 upper limit on the 68% confidence interval of the "photflux_aper" value for each science energy band
flux_aper double[6] ergs s-1 cm-2 background-subtracted flux inferred from the modified source region for each science energy band
flux_aper_lolim double[6] ergs s-1 cm-2 lower limit on the 68% confidence interval of the "flux_aper" value for each science energy band
flux_aper_hilim double[6] ergs s-1 cm-2 upper limit on the 68% confidence interval of the "flux_aper" value for each science energy band
cnts_aper90 long[6] counts total counts measured in the modified elliptical aperture for each science energy band
cnts_aper90bkg long[6] counts total counts measured in the modified elliptical background aperture for each science energy band
src_cnts_aper90 double[6] counts net background-subtracted source counts inferred from the modified elliptical aperture for each science energy band
src_cnts_aper90_lolim double[6] counts net background-subtracted source counts inferred from the modified elliptical aperture 68% lower limit for each science energy band
src_cnts_aper90_hilim double[6] counts net background-subtracted source counts inferred from the modified elliptical aperture 68% upper limit for each science energy band
src_rate_aper90 double[6] counts s-1 background-subtracted source count rate inferred from the modified elliptical aperture for each science energy band
src_rate_aper90_lolim double[6] counts s-1 lower limit on the 68% confidence interval of the "src_rate_aper90" value for each science energy band
src_rate_aper90_hilim double[6] counts s-1 upper limit on the 68% confidence interval of the "src_rate_aper90" value for each science energy band
photflux_aper90 double[6] photons s-1 cm-2 background-subtracted flux inferred from the modified elliptical aperture for each science energy band
photflux_aper90_lolim double[6] photons s-1 cm-2 lower limit on the 68% confidence interval of the "photflux_aper90" value for each science energy band
photflux_aper90_hilim double[6] photons s-1 cm-2 upper limit on the 68% confidence interval of the "photflux_aper90" value for each science energy band
flux_aper90 double[6] ergs s-1 cm-2 background-subtracted flux inferred from the modified elliptical aperture for each science energy band
flux_aper90_lolim double[6] ergs s-1 cm-2 lower limit on the 68% confidence interval of the "flux_aper90" value for each science energy band
flux_aper90_hilim double[6] ergs s-1 cm-2 upper limit on the 68% confidence interval of the "flux_aper90" value for each science energy band
ra_aper90 double[6] deg ICRS right ascension of the center of the 90% Encircled Counts Fraction of the PSF for each science energy band
dec_aper90 double[6] deg ICRS declination of the center of the 90% Encircled Counts Fraction of the PSF for each science energy band
mjr_axis_aper90 double[6] arcsec major axis of the elliptical aperture that contains the 90% Encircled Counts Fraction of the PSF at the source location for each science energy band
mnr_axis_aper90 double[6] arcsec minor axis of the elliptical aperture that contains the 90% Encircled Counts Fraction of the PSF at the source location for each science energy band
pos_angle_aper90 double[6] deg position angle of the elliptical aperture that contains the 90% Encircled Counts Fraction of the PSF at the source location for each science energy band
mjr_axis1_aper90bkg double[6] arcsec major axis of the inner annulus of the co-located, scaled elliptical background aperture for each science energy band
mnr_axis1_aper90bkg double[6] arcsec minor axis of the inner annulus of the co-located, scaled elliptical background aperture for each science energy band
mjr_axis2_aper90bkg double[6] arcsec major axis of the outer annulus of the co-located, scaled elliptical background aperture for each science energy band
mnr_axis2_aper90bkg double[6] arcsec minor axis of the outer annulus of the co-located, scaled elliptical background aperture for each science energy band
pos_angle_aper90bkg double[6] deg position angle of the co-located, scaled elliptical background aperture for each science energy band
area_aper double sq. arcsec area of the modified elliptical source region aperture (includes corrections for exclusion regions due to overlapping detections)
area_aperbkg double sq. arcseconds area of the modified annular background region aperture (includes corrections for exclusion regions due to overlapping detections)
area_aper90 double[6] sq. arcseconds area of the modified elliptical aperture from the PSF 90% ECF for each science energy band
area_aper90bkg double[6] sq. arcseconds area of the modified annular background aperture from the PSF 90% ECF for each science energy band
psf_frac_aper double[6] fraction of the PSF included in the modified elliptical source region for each science energy band
psf_frac_aperbkg double[6] fraction of the PSF included in the modified annular background region for each science energy band
psf_frac_aper90 double[6] fraction of the PSF included in the modified elliptical aperture from the PSF 90% ECF for each science energy band
psf_frac_aper90bkg double[6] fraction of the PSF included in the modified annular background aperture from the PSF 90% ECF for each science energy band
phot_nsrcs integer[6] number of sources simultaneously fit to compute aperture photometry quantities

Model Energy Fluxes flux_powlaw_aper double[6] ergs s-1 cm-2 power law model energy flux inferred from the modified source region for each science energy band
flux_powlaw_aper_lolim double[6] ergs s-1 cm-2 lower limit on the 68% confidence interval of the "flux_powlaw_aper" value for each science energy band
flux_powlaw_aper_hilim double[6] ergs s-1 cm-2 upper limit on the 68% confidence interval of the "flux_powlaw_aper" value for each science energy band
flux_bb_aper double[6] ergs s-1 cm-2 black body model energy flux inferred from the modified source region for each science energy band
flux_bb_aper_lolim double[6] ergs s-1 cm-2 lower limit on the 68% confidence interval of the "flux_bb_aper" value for each science energy band
flux_bb_aper_hilim double[6] ergs s-1 cm-2 upper limit on the 68% confidence interval of the "flux_bb_aper" value for each science energy band
flux_brems_aper double[6] ergs s-1 cm-2 bremsstrahlung model energy flux inferred from the modified source region for each science energy band
flux_brems_aper_lolim double[6] ergs s-1 cm-2 lower limit on the 68% confidence interval of the "flux_brems_aper" value for each science energy band
flux_brems_aper_hilim double[6] ergs s-1 cm-2 upper limit on the 68% confidence interval of the "flux_brems_aper" value for each science energy band
flux_apec_aper double[6] ergs s-1 cm-2 APEC model energy flux inferred from the modified source region for each science energy band
flux_apec_aper_lolim double[6] ergs s-1 cm-2 lower limit on the 68% confidence interval of the "flux_apec_aper" value for each science energy band
flux_apec_aper_hilim double[6] ergs s-1 cm-2 upper limit on the 68% confidence interval of the "flux_apec_aper" value for each science energy band
flux_powlaw_aper90 double[6] ergs s-1 cm-2 power law model energy flux inferred from the PSF 90% ECF aperture for each science energy band
flux_powlaw_aper90_lolim double[6] ergs s-1 cm-2 lower limit on the 68% confidence interval of the "flux_powlaw_aper90" value for each science energy band
flux_powlaw_aper90_hilim double[6] ergs s-1 cm-2 upper limit on the 68% confidence interval of the "flux_powlaw_aper90" value for each science energy band
flux_bb_aper90 double[6] ergs s-1 cm-2 black body model energy flux inferred from the PSF 90% ECF aperture for each science energy band
flux_bb_aper90_lolim double[6] ergs s-1 cm-2 lower limit on the 68% confidence interval of the "flux_bb_aper90" value for each science energy band
flux_bb_aper90_hilim double[6] ergs s-1 cm-2 upper limit on the 68% confidence interval of the "flux_bb_aper90" value for each science energy band
flux_brems_aper90 double[6] ergs s-1 cm-2 bremsstrahlung model energy flux inferred from the PSF 90% ECF aperture for each science energy band
flux_brems_aper90_lolim double[6] ergs s-1 cm-2 lower limit on the 68% confidence interval of the "flux_brems_aper90" value for each science energy band
flux_brems_aper90_hilim double[6] ergs s-1 cm-2 upper limit on the 68% confidence interval of the "flux_brems_aper90" value for each science energy band
flux_apec_aper90 double[6] ergs s-1 cm-2 APEC model energy flux inferred from the PSF 90% ECF aperture for each science energy band
flux_apec_aper90_lolim double[6] ergs s-1 cm-2 lower limit on the 68% confidence interval of the "flux_apec_aper90" value for each science energy band
flux_apec_aper90_hilim double[6] ergs s-1 cm-2 upper limit on the 68% confidence interval of the "flux_apec_aper90" value for each science energy band

Hardness Ratios hard_hm double hardness ratio of the hard to medium ACIS science energy bands
hard_hm_lolim double lower confidence limit on "hard_hm" value
hard_hm_hilim double upper confidence limit on "hard_hm" value
hard_hs double hardness ratio of the hard to soft ACIS science energy bands
hard_hs_lolim double lower confidence limit on "hard_hs" value
hard_hs_hilim double upper confidence limit on "hard_hs" value
hard_ms double hardness ratio of the medium to soft ACIS science energy bands
hard_ms_lolim double lower confidence limit on "hard_ms" value
hard_ms_hilim double upper confidence limit on "hard_ms" value

Spectral Properties flux_powlaw double ergs s-1 cm-2 integrated 0.5-7.0 keV flux derived from the best-fitting power law spectral fit
flux_powlaw_lolim double ergs s-1 cm-2 lower limit on the 68% confidence interval of the "flux_powlaw" value
flux_powlaw_hilim double ergs s-1 cm-2 upper limit on the 68% confidence interval of the "flux_powlaw" value
powlaw_gamma double best-fit power law photon index (γ, defined as FE ∼ E)
powlaw_gamma_lolim double lower limit on the 68% confidence interval of the "powlaw_gamma" value
powlaw_gamma_hilim double upper limit on the 68% confidence interval of the "powlaw_gamma" value
powlaw_gamma_rhat double convergence criterion for "powlaw_gamma"
powlaw_nh double HI atoms 1020 cm-2 best-fit power law NH value
powlaw_nh_lolim double HI atoms 1020 cm-2 lower limit on the 68% confidence interval of the "powlaw_nh" value
powlaw_nh_hilim double HI atoms 1020 cm-2 upper limit on the 68% confidence interval of the "powlaw_nh" value
powlaw_nh_rhat double convergence criterion for "powlaw_nh"
powlaw_ampl double amplitude of the best fitting power-law model spectral fit to the PI event data extracted from the source region
powlaw_ampl_lolim double lower confidence limit on "powlaw_ampl"
powlaw_ampl_hilim double upper confidence limit on "powlaw_ampl"
powlaw_ampl_rhat double convergence criterion for "powlaw_ampl"
powlaw_stat double χ2 (data variance) statistic per degree of freedom for the best-fitting absorbed power law spectral fit
flux_bb double ergs s-1 cm-2 integrated 0.5-7.0 keV flux derived from the best-fitting thermal (black body) spectral fit
flux_bb_lolim double ergs s-1 cm-2 lower limit on the 68% confidence interval of the "flux_bb" value
flux_bb_hilim double ergs s-1 cm-2 upper limit on the 68% confidence interval of the "flux_bb" value
bb_kt double keV best-fit thermal (black body) temperature (kT)
bb_kt_lolim double keV lower limit on the 68% confidence interval of the "bb_kt" value
bb_kt_hilim double keV upper limit on the 68% confidence interval of the "bb_kt" value
bb_kt_rhat double convergence criterion for "bb_kt"
bb_nh double HI atoms 1020 cm-2 best-fit thermal (black body) NH value
bb_nh_lolim double HI atoms 1020 cm-2 lower limit on the 68% confidence interval of the "bb_nh" value
bb_nh_hilim double HI atoms 1020 cm-2 upper limit on the 68% confidence interval of the "bb_nh" value
bb_nh_rhat double convergence criterion for "bb_nh"
bb_ampl double amplitude of the best fitting absorbed blackbody model spectral fit to the PI event data extracted from the source region
bb_ampl_lolim double lower confidence limit on "bb_ampl"
bb_ampl_hilim double upper confidence limit on "bb_ampl"
bb_ampl_rhat double convergence criterion for "bb_ampl"
bb_stat double χ2 (data variance) statistic per degree of freedom for the best-fitting thermal (blackbody) spectral fit
flux_brems double ergs s-1 cm-2 integrated 0.5-7.0 keV flux derived from the best-fitting thermal bremsstrahlung spectral fit
flux_brems_lolim double ergs s-1 cm-2 lower limit on the 68% confidence interval of the "flux_brems" value
flux_brems_hilim double ergs s-1 cm-2 upper limit on the 68% confidence interval of the "flux_brems" value
brems_kt double keV best-fit thermal bremsstrahlung temperature (kT)
brems_kt_lolim double keV lower limit on the 68% confidence interval of the "brems_kt" value
brems_kt_hilim double keV upper limit on the 68% confidence interval of the "brems_kt" value
brems_kt_rhat double convergence criterion for "brems_kt"
brems_nh double HI atoms 1020 cm-2 best-fit thermal bremsstrahlung NH value
brems_nh_lolim double HI atoms 1020 cm-2 lower limit on the 68% confidence interval of the "brems_nh" value
brems_nh_hilim double HI atoms 1020 cm-2 upper limit on the 68% confidence interval of the "brems_nh" value
brems_nh_rhat double convergence criterion for "brems_nh"
brems_norm double normalization factor of the best fitting thermal bremsstrahlung model
brems_norm_lolim double lower limit on the 68% confidence interval of the "brems_norm" value
brems_norm_hilim double upper limit on the 68% confidence interval of the "brems_norm" value
brems_norm_rhat double convergence criterion for "brems_norm"
brems_stat double χ2 (data variance) statistic per degree of freedom for the best-fitting absorbed thermal bremsstrahlung spectral fit
flux_apec double ergs s-1 cm-2 integrated 0.5-7.0 keV flux derived from the best-fitting APEC spectral fit
flux_apec_lolim double ergs s-1 cm-2 lower limit on the 68% confidence interval of the "flux_apec" value
flux_apec_hilim double ergs s-1 cm-2 upper limit on the 68% confidence interval of the "flux_apec" value
apec_kt double keV best-fit APEC plasma temperature (kT)
apec_kt_lolim double keV lower limit on the 68% confidence interval of the "apec_kt" value
apec_kt_hilim double keV upper limit on the 68% confidence interval of the "apec_kt" value
apec_kt_rhat double convergence criterion for "apec_kt"
apec_abund double best-fit metal abundances (Abundanc)
apec_abund_lolim double lower limit on the 68% confidence interval of the "apec_abund" value
apec_abund_hilim double upper limit on the 68% confidence interval of the "apec_abund" value
apec_abund_rhat double convergence criterion for "apec_abund"
apec_z double best-fit APEC redshift (z)
apec_z_lolim double lower limit on the 68% confidence interval of the "apec_z" value
apec_z_hilim double upper limit on the 68% confidence interval of the "apec_z" value
apec_z_rhat double convergence criterion for "apec_z"
apec_nh double HI atoms 1020 cm-2 best-fit APEC NH value
apec_nh_lolim double HI atoms 1020 cm-2 lower limit on the 68% confidence interval of the "apec_nh" value
apec_nh_hilim double HI atoms 1020 cm-2 upper limit on the 68% confidence interval of the "apec_nh" value
apec_nh_rhat double convergence criterion for "apec_nh"
apec_norm double normalization factor of the best fitting APEC plasma model
apec_norm_lolim double lower limit on the 68% confidence interval of the "apec_norm" value
apec_norm_hilim double upper limit on the 68% confidence interval of the "apec_norm" value
apec_norm_rhat double convergence criterion for "apec_norm"
apec_stat double χ2 (data variance) statistic per degree of freedom for the best-fitting absorbed APEC spectral fit

Source Variability var_index integer[6] variability index in the range [0,10] for each science energy band that combines the "var_prob" value with the fractions of the multi-resolution light curve output by the Gregory-Loredo analysis that are within 3σ and 5σ of the average count rate, to evaluate whether the source region flux is uniform throughout the observation
var_prob double[6] Gregory-Loredo variability probability for each science energy band
ks_prob double[6] Kolmogorov-Smirnov test probability for each science energy band
kp_prob double[6] Kuiper's test probability for each science energy band
var_sigma double[6] counts s-1 time-averaged 1σ statistical variability of the source region count rate for each science energy band
var_mean double[6] counts s-1 time-averaged value of the source region count rate for each science energy band
var_min double[6] counts s-1 minimum value of the source region count rate for each science energy band
var_max double[6] counts s-1 maximum value of the source region count rate for each science energy band

Source Timing Information livetime double s effective exposure time for the observation after applying the good time intervals and deadtime correction factor

Source Instrument Information detector string detector elements over which the background region bounding box dithers during the observation: HRC-I, HRC-S, or ACIS-<n>, where <n> is string of the CCD Ids (e.g. "ACIS-78"); see the ACIS focal plane figure in the POG.


Last modified: 5 December 2017
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