3XMM-DR7s logo

Description of all catalogue columns

The table column "Stack" comprises a short summary of how the parameter value in the summary row per stack is calculated, "Observation" of the value derived for the individual contributing observation. Values per instrument are labelled by CC, which stands for one of PN, M1, M2. The standard energy bands, defined as for 3XMM, are abbreviated by 1<= n <=5 and for the hardness ratios by 1<= i <=4. The names of columns that are also present in the other 3XMM catalogues are linked to their documentation.

Columns 1 – 4: Detection characteristics
Columns 5 – 15: Coordinates and associated identifier
Columns 16 – 233XMM counterpart: values copied from 3XMM-DR7
Columns 24 – 71: Fluxes
Columns 72 – 117: Count rates and count numbers
Columns 118 – 139: Detection and extent likelihoods
Columns 140 – 171: Hardness ratios
Columns 172 – 233: Fit characteristics
Columns 234 – 238: Quality flags
Columns 239 – 268: Inter-observation variability of sources with at least two contributing observations
Columns 269 – 273: 3XMM-DR7 intra-observation variability of sources with a DR7 light curve
Columns 274 – 284: Observation characteristics

Columns 1 – 4: Detection characteristics
Column name Format Unit Description Observation Stack
SRCID long Identifier of the detection. Sources in the stacked catalogue are marked by a leading "3". Assigned to all rows per source
OBS_ID string XMM-Newton observation identifier. Per observation null
N_OBS integer Number of observations involved in the stack. null Per stack
N_CONTRIB integer Number of observations in which the source was fitted. null Per stack
Columns 5 – 15: Coordinates and associated identifier
Column name Format Unit Description Observation Stack
RA double degrees Right ascension (J2000). Combined fit
DEC double degrees Declination (J2000). Combined fit
RADEC_ERR float arcsec Square root of the sum of the squared 1σ errors in X_IMA and Y_IMA $\sqrt{\sigma_\textrm{X_IMA}^2+\sigma_\textrm{Y_IMA}^2}$ , converted to arcsec. Combined fit
LII double degrees Galactic longitude. Combined fit
BII double degrees Galactic latitude. Combined fit
X_IMA(_ERR) float pixel X coordinate within the re-binned image and its 1σ error. Image pixels are binned to 4″×4″. Combined fit
Y_IMA(_ERR) float pixel Y coordinate within the re-binned image and its 1σ error. Image pixels are binned to 4″×4″. Combined fit
DIST_NN float arcsec Distance to the nearest neighbouring detection. Combined fit
SRCNAME string Source name in the style of the 3XMM IAU names, ending on an "s" for stacked detection. Assigned to all rows per source
Columns 16 – 23: 3XMM counterpart: values copied from 3XMM-DR7
Column name Format Unit Description Observation Stack
IAUNAME_3XMMDR7 string IAU name assigned to the nearest unique source in 3XMM-DR7. Assigned to all rows per source with a 3XMM-DR7 counterpart
SRCID_3XMMDR7 long Unique source identifier of the nearest source in 3XMM-DR7 within a correlation radius of three times the sum of the position errors. Null, if no counterpart is found. Assigned to all rows per source with a 3XMM-DR7 counterpart
DETID_3XMMDR7 long Identifier of the 3XMM-DR7 per-observation detection that contributes to the unique source SRCID_3XMMDR7, if existing. Per OBS_ID null
RA_3XMMDR7 double degrees Mean right ascension of the unique 3XMM-DR7 source and its contributing detections after field rectifications. RA per DETID_3XMMDR7 SC_RA per SRCID_3XMMDR7
DEC_3XMMDR7 double degrees Mean declination of the unique 3XMM-DR7 source and its contributing detections after field rectifications. DEC per DETID_3XMMDR7 SC_DEC per SRCID_3XMMDR7
POSERR_3XMMDR7 float arcsec Position error of the unique 3XMM-DR7 source and its contributing detections, including statistical and systematic errors from the field rectification. POSERR per DETID_3XMMDR7 SC_POSERR per SRCID_3XMMDR7
DIST_3XMMDR7 double arcsec Distance between the source and the nearest unique source / its contributing detection in 3XMM-DR7. Distance to DETID_3XMMDR7 Distance to SRCID_3XMMDR7
NDETECT_3XMMDR7 integer Number of DR7 detections N_DETECTIONS of the nearest unique source in 3XMM-DR7. null Per SRCID_3XMMDR7
Columns 24 – 71: Fluxes
Column name Format Unit Description Observation Stack
EP_FLUX float erg cm–2 s–1 All-EPIC flux: dead-time corrected count rates in the entire PSF, multiplied with the respective energy conversion factors. Null, if the exposure is zero, e.g. on chip gaps, or if the covered PSF fraction is below 15%. Weighted mean of the instrument fluxes
EP_FLUX_ERR float erg cm–2 s–1 1σ error on EP_FLUX. Mean of the instrument fluxes weighted by the inverse squared errors
EP_n_FLUX(_ERR) float erg cm–2 s–1 All-EPIC flux and 1σ flux error in energy band n. Null, if the exposure is zero or if the covered PSF fraction is below 15%. Zero with non-zero errors, if no counts are detected in spite of sufficient PSF coverage. Mean of the instrument values weighted by the inverse squared errors
CC_FLUX(_ERR) float erg cm–2 s–1 Total flux and 1σ flux error in instrument CC. Null / zero as before. Sum of fluxes and flux errors per energy band
CC_n_FLUX(_ERR) float erg cm–2 s–1 Flux and 1σ flux error per instrument CC and energy band n. Null / zero as before. Fit per input image Mean of the observation-level values weighted by the exposure time
Columns 72 – 117: Count rates and count numbers
Column name Format Unit Description Observation Stack
EP_RATE float counts s–1 All-EPIC count rate: background-subtracted and vignetting corrected count rate in the entire PSF. Null, if the exposure is zero or if the covered PSF fraction is below 15%. Zero with non-zero errors, if no counts are detected in spite of sufficient PSF coverage. Sum of the instrument-level count rates Mean of the observation-level rates weighted by the exposure time
EP_RATE_ERR float counts s–1 1σ error on the count rate. Null, if the exposure is zero or if the covered PSF fraction is below 15%. Square root of the quadratic sum of the errors per instrument Combined observation-level errors weighted by the exposure time
CC_RATE(_ERR) float counts s–1 Total count rate and count-rate error on instrument CC. Null / zero as before. Sum of the values per energy band Mean of the observation-level values weighted by the exposure time
CC_n_RATE(_ERR) float counts s–1 Count rate and count-rate error per instrument CC and energy band n. Null / zero as before. Fit per input image Mean of the observation-level values weighted by the exposure time
EP_CTS float counts s–1 All-EPIC count number: background-subtracted source counts in the entire PSF. Null, if the exposure is zero or if the covered PSF fraction is below 15%. Sum of the source counts per instrument
EP_CTS_ERR float counts s–1 1σ error on the count number. Null, if the exposure is zero or if the covered PSF fraction is below 15%. Square root of the quadratic sum of the errors per instrument
CC_CTS(_ERR) float counts s–1 Total count number and error on instrument CC. Sum of the values per energy band
Columns 118 – 139: Detection and extent likelihoods
Column name Format Unit Description Observation Stack
EP_DET_ML float Total equivalent maximum detection likelihood, normalised to two degrees of freedom. Calculated from all valid contributing images
CC_DET_ML float Equivalent maximum detection likelihood for instrument CC, normalised to two degrees of freedom. Equivalent maximum detection likelihood for instrument CC, normalised to two degrees of freedom
CC_n_DET_ML float Equivalent maximum detection likelihood per instrument CC and energy band n, normalised to two degrees of freedom. Value per input image Calculated from all valid contributing images per instrument and energy band
EXTENT float arcsec Source extent radius, derived from the model source PSF convolved with a beta profile. Below an extent of 6arcsec, it is considered unresolved and set to zero, the source is "point-like". Combined fit
EXTENT_ERR float arcsec 1σ error on the source extent radius. Null, if the extent radius is below 6arcsec. Combined fit
EXTENT_ML float Likelihood that the source is extended with radius EXTENT. Null, if the source is considered point-like. Combined fit
Columns 140 – 171: Hardness ratios
Column name Format Unit Description Observation Stack
EP_HRi float Equivalent all-EPIC hardness ratios (ri+1-ri) / (ri+1+ri) between the count rates r in energy bands i and i+1. Mean of all active instruments
EP_HRi_ERR float 1σ error on hardness ratio EP_HRi. Error propagation of the contributing values
CC_HRi(_ERR) float Hardness ratios (ri+1-ri) / (ri+1+ri) between the count rates r in energy bands i and i+1 per instrument. Per input images Mean of the observations
Columns 172 – 233: Fit characteristics
Column name Format Unit Description Observation Stack
CC_EXP float seconds Exposure map values per instrument CC, including vignetting effects. The effective good exposure time is given in the ONTIME columns, described below. Sum of the contributing images
CC_n_EXP float seconds Exposure map values per instrument CC and energy band. Fit per input image Sum of the contributing images
CC_BG float counts px–1 Background model at the central position of the source on the CCD. Null, if the exposure map is zero and if the centre of the source is located on a bad chip area. Sum of the contributing images
CC_n_BG float counts px–1 Background model in energy band n at the CCD position of the source. Sum of the contributing images in energy band n
EP_ONTIME float seconds Total good exposure time at the central position of the source on the CCD. Zero, if the centre of the source is located on a bad chip area. Maximum of the good exposure time per instrument Sum of the maximum ontimes per observation
CC_ONTIME float seconds Total good exposure time of instrument CC at the CCD position of the source. Times are calculated by the task evselect and not vignetting corrected. Read from the headers of the input files. Sum of the observation-level values.
CC_MASKFRAC float Mean chip coverage in the detection mask per instrument, weighted by the point spread function of the source. Minimum of the slightly differing values per energy band Maximum of the observation-level values
EP_OFFAX float arcmin Angular distance of the source to the boresight. Minimum of the values per instrument. null
CC_OFFAX float arcmin Angular distance of the source to the boresight in instrument CC. Combined fit null
CC_n_VIG float Vignetting fraction in instrument CC and energy band n at the central position of the source. Read from the calibration data base null
Columns 234 – 238: Quality flags
Column name Format Unit Description Observation Stack
STACK_FLAG integer Summarised quality flag of the detection. "0", if all flags are false. "1", if at least one of flags 1, 2, 3, 9 is true. "2", if at least one of flags 4–8 is true. "3", if STACK_FLAG is 2 for all contributing observations. Numeric version of EP_FLAG
EP_FLAG string Quality flags of the detection, automatically set and combined into a nine-characters string. A flag "true" means a warning on a detection condition. Worst flag of all instruments Worst flag of all observations
CC_FLAG string Quality flags in instrument CC. Set per input image Worst flag of all observations
Columns 239 – 268: Inter-observation variability of sources with at least two contributing observations
Column name Format Unit Description Observation Stack
VAR_CHI2 float Reduced chi square of inter-observation flux variability in all contributing observations with valid non-zero fluxes. null $\frac{1}{n-1}\sum_{k=1}^n \left(\frac{F_k-F_\textrm{EPIC}}{\sigma_k}\right)^2$
VAR_CHI2_n float Reduced chi squre of inter-observation flux variability in energy band n. null
VAR_PROB double Probability that the measured flux values are consistent with constant inter-observation flux, derived from VAR_CHI2. The smaller VAR_PROB, the more likely the source shows inter-observation flux variability. null $\int_{\chi^2}^\infty
 \frac{x^{\nu/2-1}e^{-x/2}}{2^{\nu/2}\Gamma(\nu/2)} dx$
VAR_PROB_n double Probability that the measured flux values are consistent with constant inter-observation flux in energy band n. null
FRATIO float Ratio between highest and lowest (non-zero, non-null) mean flux. null Fmax/Fmin
FRATIO_ERR float 1σ error on the flux ratio. null $\left(\frac{\sigma_{F\textrm{min}}^2}{F_\textrm{min}^2}+\frac{\sigma_{F\textrm{max}}^2}{F_\textrm{max}^2}\right)^{-0.5}\,\frac{F_\textrm{max}}{F_\textrm{min}}$
FRATIO_n(_ERR) float Ratio between highest and lowest mean flux in energy band n and its 1σ error. null
FLUXVAR float Largest difference between mean all-EPIC fluxes in terms of sigma. null $\max(\frac{\vert F_k-F_\vert\vert}{\sqrt{\sigma_k^2+\sigma_l^2}} \forall k,l\in[1,n])$
FLUXVAR_n float Largest difference between mean all-EPIC fluxes in terms of sigma in energy band n. null
Columns 269 – 273: 3XMM-DR7 intra-observation variability of sources with a DR7 light curve
Column name Format Unit Description Observation Stack
CHI2PROB_3XMMDR7 double EPIC chi square probability that the time series of the nearest unique source in 3XMM-DR7 is consistent with the source having constant flux during the observation. EP_CHI2PROB in 3XMM-DR7 SC_CHI2PROB in 3XMM-DR7: Minimum of all contributing 3XMM-DR7 observations
FVAR_3XMMDR7 double Fractional variance of the nearest unique source in 3XMM-DR7. FVAR in 3XMM-DR7 of the instrument with minimum CHI2PROB SC_FVAR in 3XMM-DR7: Observation with minimum CHI2PROB
FVARERR_3XMMDR7 double 1σ error on FVAR_3XMMDR7. FVAR_ERR in 3XMM-DR7 of the instrument with minimum CHI2PROB SC_FVAR_ERR in 3XMM-DR7: Observation with minimum CHI2PROB
VAR_FLAG_3XMMDR7 boolean Variability flag of the nearest unique source in 3XMM-DR7. True, if at least one exposure has CHI2PROB below 10–5. VAR_FLAG in 3XMM-DR7 SC_VAR_FLAG in 3XMM-DR7: Observation with minimum CHI2PROB
SUM_FLAG_3XMMDR7 integer SUM_FLAG in 3XMM-DR7 SC_SUM_FLAG in 3XMM-DR7
Columns 274 – 284: Observation characteristics
Column name Format Unit Description Observation Stack
MJD_FIRST double days Modified Julian Date of the start of the observation (JD–2400000.5). Read from the headers of the input files First contributing observation
MJD_LAST double days Modified Julian Date of the end of the observation (JD–2400000.5). Read from the headers of the input files Last contributing observation
PA_PNT float degrees Mean position angle of the spacecraft during the observation. File headers null
REVOLUT short XMM-Newton orbit of the observation. File headers null
CC_SUBMODE string Observing mode of instrument CC. File headers null
CC_FILTER string Filter used during the observation. File headers null
URL_3XMMDR7 string Web page of the nearest unique source in 3XMM-DR7.

Last Update: 10-July-2018