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Last modified: 5 December 2017

Stacked Observation Detections Table


The concept of Stacks are new to CSC 2.0, as discussed on the Catalog Organization page.

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
Stack Identification detect_stack_id detect stack identifier (designation of observation stack used for source detection) in the format '{acis|hrc}fJhhmmsss{+|-}ddmmss_nnn'
ra_stack detect stack tangent plane reference position, ICRS right ascension
dec_stack detect stack tangent plane reference position, ICRS declination

Instrument Information instrument string instrument used for the observation: ACIS or HRC
grating string grating used for the observation: NONE, HETG, or LETG

Processing Information ascdsver string software version used to create the Level 3 detect stack event data file
caldbver string calibration database version used to calibrate the Level 3 detect stack event data file
crdate string creation date/time of the Level 3 detect stack event data file, UTC (yyyy-mm-ddThh:mm:ss)

Source Identification region_id integer detection region identifier (component number)

Source Position and Position Errors ra double deg detection position, ICRS right ascension
dec double deg detection position, ICRS declination
err_ellipse_r0 double arcsec major radius of the 95% confidence level position error ellipse
err_ellipse_r1 double arcsec minor radius of the 95% confidence level position error ellipse
err_ellipse_ang double deg position angle of the major axis 95% confidence level error ellipse referenced from local true north.
theta_mean double arcmin mean source region aperture off-axis angle from all stacked observations

Source Significance flux_significance double[6] significance of the stacked-observation detection determined from the ratio of the stacked-observation detection flux to the estimated error in the local background for each science energy band
detect_significance double[6] significance of the stacked-observation detection computed by the stacked-observation detection algorithm for each science energy band
likelihood double[6] log-likelihood of the stacked-observation detection computed by the Maximum Likelihood Estimator fit to the photon counts distribution for each science energy band
likelihood_class string highest detection likelihood classification across all energy bands

Source Codes and Flags conf_code integer compact detection may be confused (bit encoded: 1: background region overlaps another background region; 2: background region overlaps another source region; 4: source region overlaps another background region; 8: source region overlaps another source region; 256: compact detection is overlaid on an extended detection)
dither_warning_flag boolean highest statistically significant peak in the power spectrum of the detection source region count rate occurs at the dither frequency or at a beat frequency of the dither frequency in one or more of the stacked observations
edge_code coded byte detection position, or source or background region dithered off a detector boundary (chip pixel mask) during one or more of the stacked observations (bit encoded: 1: background region dithers off detector boundary; 2:source region dithers off detector boundary; 4: detection position dither off detector boundary)
extent_code integer detection is extended, or deconvolved compact detection extent is inconsistent with a point source at the 90% confidence level in one or more of the stacked observations and energy bands (bit encoded: 1, 2, 4, 8, 16, 32: deconvolved compact detection extent is not consistent with a point source in the ACIS ultrasoft, soft, medium, hard, broad, or HRC wide (~0.1-10.0 keV) energy band, respectively; 256: extended detection)
multi_chip_code coded byte source position, or source or background region dithered multiple detector chips during one or more of the stacked observations (bit encoded: 1: background region dithers across 2 chips; 2: background region dithers across >2 chips; 4: source region dithers across 2 chips; 8: source region dithers across >2 chips; 16: detection position dithers across 2 chips; 32: detection position dither across >2 chips)
pileup_flag boolean ACIS pile-up fraction exceeds ~ 10% in all stacked observations; detection properties may be affected
sat_src_flag boolean detection is saturated in all stacked observations (strong ACIS pileup); detection properties are unreliable
streak_src_flag boolean detection located on an ACIS readout streak in all stacked observations; detection properties may be affected
var_flag boolean detection displays flux variability within one or more of the stacked observations, or between stacked observations in one or more energy bands
var_inter_hard_flag boolean detection hardness ratios are statistically inconsistent between two or more of the stacked observations
man_add_flag boolean detection was manually added to the catalog
man_inc_flag boolean detection manually included to the catalog (detection was rejected by automated criteria)
man_pos_flag boolean best fit detection position was manually modified
man_reg_flag boolean source region parameters manually modified (dimensions, initial guess position input to the MLE fit)

Source Extent major_axis double[6] arcsec 1σ radius along the major axis of the ellipse defining the deconvolved source extent for each science energy band
major_axis_lolim double[6] arcsec lower limit on the 68% confidence interval of the deconvolved source extent 1σ major axis for each science energy band
major_axis_hilim double[6] arcsec upper limit on the 68% confidence interval of the deconvolved source extent 1σ major axis for each science energy band
minor_axis double[6] arcsec 1σ radius along the minor axis of the ellipse defining the deconvolved source extent for each science energy band
minor_axis_lolim double[6] arcsec lower limit on the 68% confidence interval of the deconvolved source extent 1σ minor axis for each science energy band
minor_axis_hilim double[6] arcsec upper limit on the 68% confidence interval of the deconvolved source extent 1σ minor axis for each science energy band
pos_angle double[6] deg position angle of the major axis of the ellipse defining the deconvolved source extent for each science energy band, referenced from local true north
pos_angle_lolim double[6] deg lower limit on the 68% confidence interval of the deconvolved source extent position angle for each science energy band referenced from local true north
pos_angle_hilim double[6] deg upper limit on the 68% confidence interval of the deconvolved source extent position angle for each science energy band referenced from local true north
src_area double[6] sq. arcseconds area of the deconvolved source extent ellipse, or area of the detection polygon for extended detections for each science energy band

Source Fluxes src_cnts_aper double[6] counts aperture-corrected detection net counts inferred from the source region aperture for each science energy band
src_cnts_aper_lolim double[6] counts 68% lower confidence limit of the aperture-corrected detection net counts inferred from the source region aperture for each science energy band
src_cnts_aper_hilim double[6] counts 68% upper confidence limit of the aperture-corrected detection net counts inferred from the source region aperture for each science energy band
src_rate_aper double[6] counts s-1 aperture-corrected detection net count rate inferred from the source region aperture for each science energy band
src_rate_aper_lolim double[6] counts s-1 68% lower confidence limit of the aperture-corrected detection net count rate inferred from the source region aperture for each science energy band
src_rate_aper_hilim double[6] counts s-1 68% upper confidence limit of the aperture-corrected detection net count rate inferred from the source region aperture for each science energy band
photflux_aper double[6] photons s-1 cm-2 aperture-corrected detection net photon flux inferred from the source region aperture, calculated by counting X-ray events for ecach science energy band
photflux_aper_lolim double[6] photons s-1 cm-2 68% lower confidence limit of the aperture-corrected detection net photon flux inferred from the source region aperture, calculated by counting X-ray events for each science energy band
photflux_aper_hilim double[6] photons s-1 cm-2 68% uppoer confidence limit of the aperture-corrected detection net photon flux inferred from the source region aperture, calculated by counting X-ray events for each science energy band
flux_aper double[6] ergs s-1 cm-2 aperture-corrected detection net energy flux inferred from the source region aperture, calculated by counting X-ray events for each science energy band
flux_aper_lolim double[6] ergs s-1 cm-2 68% lower confidence limit of the aperture-corrected detection net energy flux inferred from the source region aperture, calculated by counting X-ray events for each science energy band
flux_aper_hilim double[6] ergs s-1 cm-2 68% upper confidence limit of the aperture-corrected detection net energy flux inferred from the source region aperture, calculated by counting X-ray events for each science energy band
src_cnts_aper90 double[6] counts aperture-corrected detection net counts inferred from the PSF 90% ECF aperture for each science energy band
src_cnts_aper90_lolim double[6] counts 68% lower confidence limit of the aperture-corrected detection net counts inferred from the PSF 90% ECF aperture for each science energy band
src_cnts_aper90_hilim double[6] counts 68% upper confidence limit of the aperture-corrected detection net counts inferred from the PSF 90% ECF aperture for each science energy band
src_rate_aper90 double[6] counts s-1 aperture-corrected detection net count rate inferred from the PSF 90% ECF aperture for each science energy band
src_rate_aper90_lolim double[6] counts s-1 68% lower confidence limit of the aperture-corrected detection net count rate inferred from the PSF 90% ECF aperture for each science energy band
src_rate_aper90_hilim double[6] counts s-1 68% upper confidence limit of the aperture-corrected detection net count rate inferred from the PSF 90% ECF aperture for each science energy band
photflux_aper90 double[6] photons s-1 cm-2 aperture-corrected detection net photon flux inferred from the PSF 90% ECF aperture, calculated by counting X-ray events for each science energy band
photflux_aper90_lolim double[6] photons s-1 cm-2 68% lower confidence limit of the aperture-corrected detection net photon flux inferred from the PSF 90% ECF aperture, calculated by counting X-ray events for each science energy band
photflux_aper90_hilim double[6] photons s-1 cm-2 68% upper confidence limit of the aperture-corrected detection net photon flux inferred from the PSF 90% ECF aperture, calculated by counting X-ray events for each science energy band
flux_aper90 double[6] ergs s-1 cm-2 aperture-corrected detection net energy flux inferred from the PSF 90% ECF aperture, calculated by counting X-ray events for each science energy band
flux_aper90_lolim double[6] ergs s-1 cm-2 68% lower confidence limit of the aperture-corrected detection net energy flux inferred from the PSF 90% ECF aperture, calculated by counting X-ray events for each science energy band
flux_aper90_hilim double[6] ergs s-1 cm-2 68% upper confidence limit of the aperture-corrected detection net energy flux inferred from the PSF 90% ECF aperture, calculated by counting X-ray events for each science energy band

Source Aperture ra_aper double deg ICRS right ascension of the center of the source region and background region apertures
dec_aper double deg ICRS declination of the center of the source region and background region apertures
mjr_axis_aper double arcsec semi-major axis of the elliptical source region aperture
mnr_axis_aper double arcsec semi-minor axis of the elliptical source region aperture
pos_angle_aper double deg position angle of the semi-major axis of the elliptical source region aperture referenced from local true north
mjr_axis1_aperbkg double arcsec semi-major axis of the inner ellipse of the annular background region aperture
mnr_axis1_aperbkg double arcsec semi-minor axis of the inner ellipse of the annular background region aperture
mjr_axis2_aperbkg double arcsec semi-major axis of the outer ellipse of the annular background region aperture
mnr_axis2_aperbkg double arcsec semi-minor axis of the outer ellipse of the annular background region aperture
pos_angle_aperbkg double deg position angle of the inner and outer semi-major axes of the annular background region aperture referenced from local true north
phot_nsrcs integer[6] number of detections simultaneously fit to compute aperture photometry quantities

Hardness Ratios hard_hm double hardness ratio of the hard to medium ACIS science energy bands
hard_hm_lolim double 68% lower confidence limit on "hard_hm" value
hard_hm_hilim double 68% upper confidence limit on "hard_hm" value
var_inter_hard_prob_hm double inter-stacked-observation hardness ratio variability probability of the hard to medium ACIS science energy bands
var_inter_hard_sigma_prob_hm double inter-stacked-observation hardness ratio variability standard deviation of the hard to medium ACIS science energy bands
hard_hs double hardness ratio of the hard to soft ACIS science energy bands
hard_hs_lolim double 68% lower confidence limit on "hard_hs" value
hard_hs_hilim double 68% upper confidence limit on "hard_hs" value
var_inter_hard_prob_hs double inter-stacked-observation hardness ratio variability probability of the hard to soft ACIS science energy bands
var_inter_hard_sigma_prob_hs double inter-stacked-observation hardness ratio variability standard deviation of the hard to soft ACIS science energy bands
hard_ms double hardness ratio of the medium to soft ACIS science energy bands
hard_ms_lolim double 68% lower confidence limit on "hard_ms" value
hard_ms_hilim double 68% upper confidence limit on "hard_ms" value
var_inter_hard_prob_ms double inter-stacked-observation hardness ratio variability probability of the medium to soft ACIS science energy bands
var_inter_hard_sigma_prob_ms double inter-stacked-observation hardness ratio variability standard deviation of the medium to soft ACIS science energy bands

Temporal Variability var_intra_index integer[6] intra-observation Gregory-Loredo variability index in the range [0, 10]: indicates whether the source region photon flux is constant within an observation (highest value across all stacked observations) for each science energy band
var_intra_prob double[6] intra-observation Gregory-Loredo variability probability (highest value across all stacked observations for each science energy band
ks_intra_prob double[6] intra-observation Kolmogorov-Smirnov test variability probability (highest value across all observations) for each science energy band
kp_intra_prob double[6] intra-observation Kuiper's test variability probability (highest value across all stacked observations) for each science energy band
var_inter_index integer[6] inter-stacked-observation variability index in the range [0, 10]: indicates whether the source region photon flux is constant between observations for each science energy band
var_inter_prob double[6] inter-stacked observation variability probability, calculated from the χ2 distribution of the photon fluxes of the individual observations for each science energy band
var_inter_sigma double[6] photons s-1 cm-2 inter-stacked-observation flux variability standard deviation; the spread of the individual observation photon fluxes about the error weighted mean for each science energy band

Timing Information livetime double s effective stacked observation exposure time at the location of the detection after applying the good time intervals and deadtime correction factor


Last modified: 5 December 2017
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