Home | Overview | Browser | Access | Login | Cookbook | nonSurvey 
 
  WSA logo

Glossary of WSA attributes

This Glossary alphabetically lists all attributes used in the UKIDSSDR11 database(s) held in the WSA. If you would like to have more information about the schema tables please use the UKIDSSDR11 Schema Browser (other Browser versions).
A B C D E F G H I J K L M
N O P Q R S T U V W X Y Z

Z

NameSchema TableDatabaseDescriptionTypeLengthUnitDefault ValueUnified Content Descriptor
z allwise_sc WISE Unit sphere position z value float 8      
z11 Multiframe WSA Spherical: Z11 {image primary HDU keyword: Z11} real 4   -0.9999995e9  
z11 Multiframe WSACalib Spherical: Z11 {image primary HDU keyword: Z11} real 4   -0.9999995e9  
z11 Multiframe WSATransit Spherical: Z11 {image primary HDU keyword: Z11} real 4   -0.9999995e9  
z11 Multiframe WSAUHS Spherical: Z11 {image primary HDU keyword: Z11} real 4   -0.9999995e9  
z7 Multiframe WSA Coma: Z7 {image primary HDU keyword: Z7} real 4   -0.9999995e9  
z7 Multiframe WSACalib Coma: Z7 {image primary HDU keyword: Z7} real 4   -0.9999995e9  
z7 Multiframe WSATransit Coma: Z7 {image primary HDU keyword: Z7} real 4   -0.9999995e9  
z7 Multiframe WSAUHS Coma: Z7 {image primary HDU keyword: Z7} real 4   -0.9999995e9  
z8 Multiframe WSA Coma: Z8 {image primary HDU keyword: Z8} real 4   -0.9999995e9  
z8 Multiframe WSACalib Coma: Z8 {image primary HDU keyword: Z8} real 4   -0.9999995e9  
z8 Multiframe WSATransit Coma: Z8 {image primary HDU keyword: Z8} real 4   -0.9999995e9  
z8 Multiframe WSAUHS Coma: Z8 {image primary HDU keyword: Z8} real 4   -0.9999995e9  
zAperMag1 calSynopticSource WSACalib Extended source Z aperture corrected mag (1.0 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG
zAperMag1Err calSynopticSource WSACalib Error in extended source Z mag (1.0 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR
zAperMag2 calSynopticSource WSACalib Extended source Z aperture corrected mag (1.4 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG
zAperMag2Err calSynopticSource WSACalib Error in extended source Z mag (1.4 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR
zAperMag3 calSource WSACalib Default point/extended source Z aperture corrected mag (2.0 arcsec aperture diameter)
If in doubt use this flux estimator
real 4 mag -0.9999995e9 PHOT_MAG
zAperMag3 calSynopticSource WSACalib Default point/extended source Z aperture corrected mag (2.0 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG
zAperMag3 gcsPointSource, gcsZYJHKsource, reliableGcsPointSource WSA Default point source Z aperture corrected mag (2.0 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG
zAperMag3 gcsSource WSA Default point source Z aperture corrected mag (2.0 arcsec aperture diameter)
If in doubt use this flux estimator
real 4 mag -0.9999995e9 PHOT_MAG
zAperMag3Err calSource, calSynopticSource WSACalib Error in default point/extended source Z mag (2.0 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR
zAperMag3Err gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource WSA Error in default point source Z mag (2.0 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR
zAperMag4 calSource, calSynopticSource WSACalib Extended source Z aperture corrected mag (2.8 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG
zAperMag4 gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource WSA Point source Z aperture corrected mag (2.8 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG
zAperMag4Err calSource, calSynopticSource WSACalib Error in extended source Z mag (2.8 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR
zAperMag4Err gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource WSA Error in point source Z mag (2.8 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR
zAperMag5 calSynopticSource WSACalib Extended source Z aperture corrected mag (4.0 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG
zAperMag5Err calSynopticSource WSACalib Error in extended source Z mag (4.0 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR
zAperMag6 calSource WSACalib Extended source Z aperture corrected mag (5.7 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG
zAperMag6 gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource WSA Point source Z aperture corrected mag (5.7 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG
zAperMag6Err calSource WSACalib Error in extended source Z mag (5.7 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR
zAperMag6Err gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource WSA Error in point source Z mag (5.7 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR
zApFillFac StackObjectAttributes PS1DR2 Aperture fill factor from z filter stack detection. real 4   -999  
zApFlux StackObjectAttributes PS1DR2 Aperture flux from z filter stack detection. real 4 Janskys -999  
zApFluxErr StackObjectAttributes PS1DR2 Error in aperture flux from z filter stack detection. real 4 Janskys -999  
zApMag StackObjectThin PS1DR2 Aperture magnitude from z filter stack detection. real 4 AB magnitudes -999  
zApMagErr StackObjectThin PS1DR2 Error in aperture magnitude from z filter stack detection. real 4 AB magnitudes -999  
zApRadius StackObjectAttributes PS1DR2 Aperture radius for z filter stack detection. real 4 arcsec -999  
zaStratAst calVarFrameSetInfo WSACalib Strateva parameter, a, in fit to astrometric rms vs magnitude in Z band, see Sesar et al. 2007. real 4   -0.9999995e9  
The best fit solution to the expected RMS position around the mean for all objects in the frameset. Objects were binned in ranges of magnitude and the median RMS (after clipping out variable objects using the median-absolute deviation) was calculated. The Strateva function $\zeta(m)>=a+b\,10^{0.4m}+c\,10^{0.8m}$ was fit, where $\zeta(m)$ is the expected RMS as a function of magnitude. The chi-squared and number of degrees of freedom are also calculated.
zaStratPht calVarFrameSetInfo WSACalib Strateva parameter, a, in fit to photometric rms vs magnitude in Z band, see Sesar et al. 2007. real 4   -0.9999995e9  
The best fit solution to the expected RMS brightness (in magnitudes) for all objects in the frameset. Objects were binned in ranges of magnitude and the median RMS (after clipping out variable objects using the median-absolute deviation) was calculated. The Strateva function $\zeta(m)>=a+b\,10^{0.4m}+c\,10^{0.8m}$ was fit, where $\zeta(m)$ is the expected RMS as a function of magnitude. The chi-squared and number of degrees of freedom are also calculated. This technique was used in Sesar et al. 2007, AJ, 134, 2236.
zbestAper calVariability WSACalib Best aperture (1-6) for photometric statistics in the Z band int 4   -9999  
Aperture magnitude (1-6) which gives the lowest RMS for the object. All apertures have the appropriate aperture correction. This can give better values in crowded regions than aperMag3 (see Irwin et al. 2007, MNRAS, 375, 1449)
zbStratAst calVarFrameSetInfo WSACalib Strateva parameter, b, in fit to astrometric rms vs magnitude in Z band, see Sesar et al. 2007. real 4   -0.9999995e9  
The best fit solution to the expected RMS position around the mean for all objects in the frameset. Objects were binned in ranges of magnitude and the median RMS (after clipping out variable objects using the median-absolute deviation) was calculated. The Strateva function $\zeta(m)>=a+b\,10^{0.4m}+c\,10^{0.8m}$ was fit, where $\zeta(m)$ is the expected RMS as a function of magnitude. The chi-squared and number of degrees of freedom are also calculated.
zbStratPht calVarFrameSetInfo WSACalib Strateva parameter, b, in fit to photometric rms vs magnitude in Z band, see Sesar et al. 2007. real 4   -0.9999995e9  
The best fit solution to the expected RMS brightness (in magnitudes) for all objects in the frameset. Objects were binned in ranges of magnitude and the median RMS (after clipping out variable objects using the median-absolute deviation) was calculated. The Strateva function $\zeta(m)>=a+b\,10^{0.4m}+c\,10^{0.8m}$ was fit, where $\zeta(m)$ is the expected RMS as a function of magnitude. The chi-squared and number of degrees of freedom are also calculated. This technique was used in Sesar et al. 2007, AJ, 134, 2236.
zchiSqAst calVarFrameSetInfo WSACalib Goodness of fit of Strateva function to astrometric data in Z band real 4   -0.9999995e9  
The best fit solution to the expected RMS position around the mean for all objects in the frameset. Objects were binned in ranges of magnitude and the median RMS (after clipping out variable objects using the median-absolute deviation) was calculated. The Strateva function $\zeta(m)>=a+b\,10^{0.4m}+c\,10^{0.8m}$ was fit, where $\zeta(m)$ is the expected RMS as a function of magnitude. The chi-squared and number of degrees of freedom are also calculated.
zchiSqpd calVariability WSACalib Chi square (per degree of freedom) fit to data (mean and expected rms) real 4   -0.9999995e9  
The photometry is calculated for good observations in the best aperture. The mean, rms, median, median absolute deviation, minMag and maxMag are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. The number of good detections that are more than 3 standard deviations can indicate a distribution with many outliers. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.
zchiSqPht calVarFrameSetInfo WSACalib Goodness of fit of Strateva function to photometric data in Z band real 4   -0.9999995e9  
The best fit solution to the expected RMS brightness (in magnitudes) for all objects in the frameset. Objects were binned in ranges of magnitude and the median RMS (after clipping out variable objects using the median-absolute deviation) was calculated. The Strateva function $\zeta(m)>=a+b\,10^{0.4m}+c\,10^{0.8m}$ was fit, where $\zeta(m)$ is the expected RMS as a function of magnitude. The chi-squared and number of degrees of freedom are also calculated. This technique was used in Sesar et al. 2007, AJ, 134, 2236.
zClass calSource, calSynopticSource WSACalib discrete image classification flag in Z smallint 2   -9999 CLASS_MISC
zClass gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource WSA discrete image classification flag in Z smallint 2   -9999 CLASS_MISC
zClassStat calSource, calSynopticSource WSACalib N(0,1) stellarness-of-profile statistic in Z real 4   -0.9999995e9 STAT_PROP
zClassStat gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource WSA N(0,1) stellarness-of-profile statistic in Z real 4   -0.9999995e9 STAT_PROP
zcStratAst calVarFrameSetInfo WSACalib Strateva parameter, c, in fit to astrometric rms vs magnitude in Z band, see Sesar et al. 2007. real 4   -0.9999995e9  
The best fit solution to the expected RMS position around the mean for all objects in the frameset. Objects were binned in ranges of magnitude and the median RMS (after clipping out variable objects using the median-absolute deviation) was calculated. The Strateva function $\zeta(m)>=a+b\,10^{0.4m}+c\,10^{0.8m}$ was fit, where $\zeta(m)$ is the expected RMS as a function of magnitude. The chi-squared and number of degrees of freedom are also calculated.
zcStratPht calVarFrameSetInfo WSACalib Strateva parameter, c, in fit to photometric rms vs magnitude in Z band, see Sesar et al. 2007. real 4   -0.9999995e9  
The best fit solution to the expected RMS brightness (in magnitudes) for all objects in the frameset. Objects were binned in ranges of magnitude and the median RMS (after clipping out variable objects using the median-absolute deviation) was calculated. The Strateva function $\zeta(m)>=a+b\,10^{0.4m}+c\,10^{0.8m}$ was fit, where $\zeta(m)$ is the expected RMS as a function of magnitude. The chi-squared and number of degrees of freedom are also calculated. This technique was used in Sesar et al. 2007, AJ, 134, 2236.
zd twomass_scn 2MASS Scan's distance from the zenith at beginning of scan. real 4 degrees   POS_ZD_RES
zd twomass_sixx2_scn 2MASS beginning zenith distance of scan data real 4 deg    
zDeblend calSource WSACalib placeholder flag indicating parent/child relation in Z int 4   -99999999 CODE_MISC
This CASU pipeline processing source extraction flag is a placeholder only, and is always set to zero in all passbands in the merged source lists. If you need to know when a particular image detection is a component of a deblend or not, test bit 4 of attribute ppErrBits (see corresponding glossary entry) which is set by WFAU's post-processing software based on testing the areal profiles aprof2-8 (these are set by CASU to -1 for deblended components, or positive values for non-deblended detections). We encode this in an information bit of ppErrBits for convenience when querying the merged source tables.
zDeblend calSynopticSource WSACalib placeholder flag indicating parent/child relation in Z int 4   -99999999 CODE_MISC
zDeblend gcsPointSource, gcsZYJHKsource, reliableGcsPointSource WSA placeholder flag indicating parent/child relation in Z int 4   -99999999 CODE_MISC
zDeblend gcsSource WSA placeholder flag indicating parent/child relation in Z int 4   -99999999 CODE_MISC
This CASU pipeline processing source extraction flag is a placeholder only, and is always set to zero in all passbands in the merged source lists. If you need to know when a particular image detection is a component of a deblend or not, test bit 4 of attribute ppErrBits (see corresponding glossary entry) which is set by WFAU's post-processing software based on testing the areal profiles aprof2-8 (these are set by CASU to -1 for deblended components, or positive values for non-deblended detections). We encode this in an information bit of ppErrBits for convenience when querying the merged source tables.
zdec StackObjectThin PS1DR2 Declination from z filter stack detection. float 8 degrees -999  
zdecErr StackObjectThin PS1DR2 Declination error from z filter stack detection. real 4 arcsec -999  
zEll calSource, calSynopticSource WSACalib 1-b/a, where a/b=semi-major/minor axes in Z real 4   -0.9999995e9 PHYS_ELLIPTICITY
zEll gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource WSA 1-b/a, where a/b=semi-major/minor axes in Z real 4   -0.9999995e9 PHYS_ELLIPTICITY
zeNum calMergeLog, calSynopticMergeLog WSACalib the extension number of this Z frame tinyint 1     NUMBER
zeNum gcsMergeLog WSA the extension number of this Z frame tinyint 1     NUMBER
zeNum gcsZYJHKmergeLog WSA the extension number of this frame tinyint 1     NUMBER
zEpoch StackObjectThin PS1DR2 Modified Julian Date of the mean epoch of images contributing to the the z-band stack (equinox J2000). float 8 days -999  
zeroPoint ExternalProduct WSA Zeropoint of each product real 4   -0.9999995e9  
zeroPoint ExternalProduct WSAUHS Zeropoint of each product real 4   -0.9999995e9  
zeropoint RequiredMosaicTopLevel WSAUHS Zeropoint of each product real 4   -0.9999995e9  
zErrBits calSource, calSynopticSource WSACalib processing warning/error bitwise flags in Z int 4   -99999999 CODE_MISC
Apparently not actually an error bit flag, but a count of the number of zero confidence pixels in the default (2 arcsec diameter) aperture.
zErrBits gcsPointSource, gcsZYJHKsource, reliableGcsPointSource WSA processing warning/error bitwise flags in Z int 4   -99999999 CODE_MISC
zErrBits gcsSource WSA processing warning/error bitwise flags in Z int 4   -99999999 CODE_MISC
Apparently not actually an error bit flag, but a count of the number of zero confidence pixels in the default (2 arcsec diameter) aperture.
zEta calSource, calSynopticSource WSACalib Offset of Z detection from master position (+north/-south) real 4 arcsec -0.9999995e9 POS_EQ_DEC_OFF
When associating individual passband detections into merged sources, a generous (in terms of the positional uncertainties) pairing radius of 2.0 (UKIDSS LAS and GPS; UHS; also non-survey programmes) or 1.0 (UKIDSS GPS, DXS and UDS) arcseconds is used, the higher value enabling pairing of moving sources when epoch separations may be several years. Such a large association criterion can of course lead to spurious pairings in the merged sources lists (although note that between passband pairs, handshake pairing is done: both passbands must agree that the candidate pair is their nearest neighbour for the pair to propagate through into the merged source table). In order to help filter spurious pairings out, and assuming that large positional offsets between the different passband detections are not expected (e.g. because of source motion, or larger than usual positional uncertainties) then the attributes Xi and Eta can be used to filter any pairings with suspiciously large offsets in one or more bands. For example, for a clean sample of QSOs from the LAS, you might wish to insist that the offsets in the selected sample are all below 1 arcsecond: simply add WHERE clauses into the SQL sample selection script to exclude all Xi and Eta values larger than the threshold you want. NB: the master position is the position of the detection in the shortest passband in the set, rather than the ra/dec of the source as stored in source attributes of the same name. The former is used in the pairing process, while the latter is generally the optimally weighted mean position from an astrometric solution or other combinatorial process of all individual detection positions across the available passbands.
zEta gcsPointSource, gcsZYJHKsource, reliableGcsPointSource WSA Offset of Z detection from master position (+north/-south) real 4 arcsec -0.9999995e9 POS_EQ_DEC_OFF
zEta gcsSource WSA Offset of Z detection from master position (+north/-south) real 4 arcsec -0.9999995e9 POS_EQ_DEC_OFF
When associating individual passband detections into merged sources, a generous (in terms of the positional uncertainties) pairing radius of 2.0 (UKIDSS LAS and GPS; UHS; also non-survey programmes) or 1.0 (UKIDSS GPS, DXS and UDS) arcseconds is used, the higher value enabling pairing of moving sources when epoch separations may be several years. Such a large association criterion can of course lead to spurious pairings in the merged sources lists (although note that between passband pairs, handshake pairing is done: both passbands must agree that the candidate pair is their nearest neighbour for the pair to propagate through into the merged source table). In order to help filter spurious pairings out, and assuming that large positional offsets between the different passband detections are not expected (e.g. because of source motion, or larger than usual positional uncertainties) then the attributes Xi and Eta can be used to filter any pairings with suspiciously large offsets in one or more bands. For example, for a clean sample of QSOs from the LAS, you might wish to insist that the offsets in the selected sample are all below 1 arcsecond: simply add WHERE clauses into the SQL sample selection script to exclude all Xi and Eta values larger than the threshold you want. NB: the master position is the position of the detection in the shortest passband in the set, rather than the ra/dec of the source as stored in source attributes of the same name. The former is used in the pairing process, while the latter is generally the optimally weighted mean position from an astrometric solution or other combinatorial process of all individual detection positions across the available passbands.
zexpML calVarFrameSetInfo WSACalib Expected magnitude limit of frameSet in this in Z band. real 4   -0.9999995e9  
The expected magnitude limit of an intermediate stack, based on the total exposure time. expML=Filter.oneSecML+1.25*log10(totalExpTime). Since different intermediate stacks can have different exposure times, the totalExpTime is the minimum, as long as the number of stacks with this minimum make up 10% of the total. This is a more conservative treatment than just taking the mean or median total exposure time.
zExpRms calVariability WSACalib Rms calculated from polynomial fit to modal RMS as a function of magnitude in Z band real 4 mag -0.9999995e9  
The photometry is calculated for good observations in the best aperture. The mean, rms, median, median absolute deviation, minMag and maxMag are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. The number of good detections that are more than 3 standard deviations can indicate a distribution with many outliers. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.
zexpTime StackObjectAttributes PS1DR2 Exposure time of the z filter stack. Necessary for converting listed fluxes and magnitudes back to measured ADU counts. real 4 seconds -999  
zExtNSigma StackObjectAttributes PS1DR2 An extendedness measure for the z filter stack detection based on the deviation between PSF and Kron (1980) magnitudes, normalized by the PSF magnitude uncertainty. real 4   -999  
zFlags MeanObject PS1DR2 Information flag bitmask for mean object from z filter detections. Values listed in ObjectFilterFlags. int 4   0  
zGausig calSource, calSynopticSource WSACalib RMS of axes of ellipse fit in Z real 4 pixels -0.9999995e9 MORPH_PARAM
zGausig gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource WSA RMS of axes of ellipse fit in Z real 4 pixels -0.9999995e9 MORPH_PARAM
zHallMag calSource WSACalib Total point source Z mag real 4 mag -0.9999995e9 PHOT_MAG
zHallMag gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource WSA Total point source Z mag real 4 mag -0.9999995e9 PHOT_MAG
zHallMagErr calSource WSACalib Error in total point source Z mag real 4 mag -0.9999995e9 ERROR
zHallMagErr gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource WSA Error in total point source Z mag real 4 mag -0.9999995e9 ERROR
zinfoFlag StackObjectThin PS1DR2 Information flag bitmask indicating details of the z filter stack photometry. Values listed in DetectionFlags. bigint 8   0  
zinfoFlag2 StackObjectThin PS1DR2 Information flag bitmask indicating details of the z filter stack photometry. Values listed in DetectionFlags2. int 4   0  
zinfoFlag3 StackObjectThin PS1DR2 Information flag bitmask indicating details of the z filter stack photometry. Values listed in DetectionFlags3. int 4   0  
zIntRms calVariability WSACalib Intrinsic rms in Z-band real 4 mag -0.9999995e9  
The photometry is calculated for good observations in the best aperture. The mean, rms, median, median absolute deviation, minMag and maxMag are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. The number of good detections that are more than 3 standard deviations can indicate a distribution with many outliers. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.
zippDetectID StackObjectAttributes, StackObjectThin PS1DR2 IPP internal detection identifier. bigint 8      
zisDefAst calVarFrameSetInfo WSACalib Use a default model for the astrometric noise in Z band. tinyint 1   0  
zisDefPht calVarFrameSetInfo WSACalib Use a default model for the photometric noise in Z band. tinyint 1   0  
zKronFlux StackObjectAttributes PS1DR2 Kron (1980) flux from z filter stack detection. real 4 Janskys -999  
zKronFluxErr StackObjectAttributes PS1DR2 Error in Kron (1980) flux from z filter stack detection. real 4 Janskys -999  
zKronMag StackObjectThin PS1DR2 Kron (1980) magnitude from z filter stack detection. real 4 AB magnitudes -999  
zKronMagErr StackObjectThin PS1DR2 Error in Kron (1980) magnitude from z filter stack detection. real 4 AB magnitudes -999  
zKronRad StackObjectAttributes PS1DR2 Kron (1980) radius from z filter stack detection. real 4 arcsec -999  
zMagMAD calVariability WSACalib Median Absolute Deviation of Z magnitude real 4 mag -0.9999995e9  
The photometry is calculated for good observations in the best aperture. The mean, rms, median, median absolute deviation, minMag and maxMag are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. The number of good detections that are more than 3 standard deviations can indicate a distribution with many outliers. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.
zMagRms calVariability WSACalib rms of Z magnitude real 4 mag -0.9999995e9  
The photometry is calculated for good observations in the best aperture. The mean, rms, median, median absolute deviation, minMag and maxMag are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. The number of good detections that are more than 3 standard deviations can indicate a distribution with many outliers. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.
zmaxCadence calVariability WSACalib maximum gap between observations real 4 days -0.9999995e9  
The observations are classified as good, flagged or missing. Flagged observations are ones where the object has a ppErrBit flag. Missing observations are observations of the part of the sky that include the position of the object, but had no detection. All the statistics are calculated from good observations. The cadence parameters give the minimum, median and maximum time between observations, which is useful to know if the data could be used to find a particular type of variable.
zMaxMag calVariability WSACalib Maximum magnitude in Z band, of good detections real 4   -0.9999995e9  
The photometry is calculated for good observations in the best aperture. The mean, rms, median, median absolute deviation, minMag and maxMag are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. The number of good detections that are more than 3 standard deviations can indicate a distribution with many outliers. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.
zMeanApMag MeanObject PS1DR2 Mean aperture magnitude from z filter detections. real 4 AB magnitudes -999  
zMeanApMagErr MeanObject PS1DR2 Error in mean aperture magnitude from z filter detections. real 4 AB magnitudes -999  
zMeanApMagNpt MeanObject PS1DR2 Number of measurements included in mean aperture magnitude from z filter detections. smallint 2   -999  
zMeanApMagStd MeanObject PS1DR2 Standard deviation of aperture magnitudes from z filter detections. real 4 AB magnitudes -999  
zMeanKronMag MeanObject PS1DR2 Mean Kron (1980) magnitude from z filter detections. real 4 AB magnitudes -999  
zMeanKronMagErr MeanObject PS1DR2 Error in mean Kron (1980) magnitude from z filter detections. real 4 AB magnitudes -999  
zMeanKronMagNpt MeanObject PS1DR2 Number of measurements included in mean Kron (1980) magnitude from z filter detections. smallint 2   -999  
zMeanKronMagStd MeanObject PS1DR2 Standard deviation of Kron (1980) magnitudes from z filter detections. real 4 AB magnitudes -999  
zmeanMag calVariability WSACalib Mean Z magnitude real 4 mag -0.9999995e9  
The photometry is calculated for good observations in the best aperture. The mean, rms, median, median absolute deviation, minMag and maxMag are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. The number of good detections that are more than 3 standard deviations can indicate a distribution with many outliers. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.
zMeanPSFMag MeanObject PS1DR2 Mean PSF magnitude from z filter detections. real 4 AB magnitudes -999  
zMeanPSFMagErr MeanObject PS1DR2 Error in mean PSF magnitude from z filter detections. real 4 AB magnitudes -999  
zMeanPSFMagMax MeanObject PS1DR2 Maximum PSF magnitude from z filter detections. real 4 AB magnitudes -999  
zMeanPSFMagMin MeanObject PS1DR2 Minimum PSF magnitude from z filter detections. real 4 AB magnitudes -999  
zMeanPSFMagNpt MeanObject PS1DR2 Number of measurements included in mean PSF magnitude from z filter detections. smallint 2   -999  
zMeanPSFMagStd MeanObject PS1DR2 Standard deviation of PSF magnitudes from z filter detections. real 4 AB magnitudes -999  
zmedCadence calVariability WSACalib median gap between observations real 4 days -0.9999995e9  
The observations are classified as good, flagged or missing. Flagged observations are ones where the object has a ppErrBit flag. Missing observations are observations of the part of the sky that include the position of the object, but had no detection. All the statistics are calculated from good observations. The cadence parameters give the minimum, median and maximum time between observations, which is useful to know if the data could be used to find a particular type of variable.
zmedianMag calVariability WSACalib Median Z magnitude real 4 mag -0.9999995e9  
The photometry is calculated for good observations in the best aperture. The mean, rms, median, median absolute deviation, minMag and maxMag are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. The number of good detections that are more than 3 standard deviations can indicate a distribution with many outliers. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.
zmfID calMergeLog, calSynopticMergeLog WSACalib the UID of the relevant Z multiframe bigint 8     ID_FRAME
zmfID gcsMergeLog WSA the UID of the relevant Z multiframe bigint 8     ID_FRAME
zmfID gcsZYJHKmergeLog WSA the UID of the relevant multiframe bigint 8     ID_FRAME
zminCadence calVariability WSACalib minimum gap between observations real 4 days -0.9999995e9  
The observations are classified as good, flagged or missing. Flagged observations are ones where the object has a ppErrBit flag. Missing observations are observations of the part of the sky that include the position of the object, but had no detection. All the statistics are calculated from good observations. The cadence parameters give the minimum, median and maximum time between observations, which is useful to know if the data could be used to find a particular type of variable.
zMinMag calVariability WSACalib Minimum magnitude in Z band, of good detections real 4   -0.9999995e9  
The photometry is calculated for good observations in the best aperture. The mean, rms, median, median absolute deviation, minMag and maxMag are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. The number of good detections that are more than 3 standard deviations can indicate a distribution with many outliers. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.
zmomentR1 StackObjectAttributes PS1DR2 First radial moment for z filter stack detection. real 4 arcsec -999  
zmomentRH StackObjectAttributes PS1DR2 Half radial moment (r^0.5 weighting) for z filter stack detection. real 4 arcsec^0.5 -999  
zmomentXX StackObjectAttributes PS1DR2 Second moment M_xx for z filter stack detection. real 4 arcsec^2 -999  
zmomentXY StackObjectAttributes PS1DR2 Second moment M_xy for z filter stack detection. real 4 arcsec^2 -999  
zmomentYY StackObjectAttributes PS1DR2 Second moment M_yy for z filter stack detection. real 4 arcsec^2 -999  
zmyExt calSource WSACalib Extended source colour Z-Y (using aperMag3) real 4 mag -0.9999995e9 PHOT_COLOR
Default colours from pairs of adjacent passbands within a given set (e.g. Y-J, J-H and H-K for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the point-source colours and extended source colours are computed from the aperture corrected AperMag3 fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands) and generally good signal-to-noise. At some point in the future, this may be changed such that point-source colours will be computed from the PSF-fitted measures and extended source colours computed from the 2-d Sersic model profile fits.
zmyExt gcsPointSource, gcsZYJHKsource, reliableGcsPointSource WSA Extended source colour Z-Y (using aperMag3) real 4 mag -0.9999995e9 PHOT_COLOR
zmyExt gcsSource WSA Extended source colour Z-Y (using aperMag3) real 4 mag -0.9999995e9 PHOT_COLOR
Default colours from pairs of adjacent passbands within a given set (e.g. Y-J, J-H and H-K for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the point-source colours and extended source colours are computed from the aperture corrected AperMag3 fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands) and generally good signal-to-noise. At some point in the future, this may be changed such that point-source colours will be computed from the PSF-fitted measures and extended source colours computed from the 2-d Sersic model profile fits.
zmyExtErr calSource WSACalib Error on extended source colour Z-Y real 4 mag -0.9999995e9 ERROR
Default colours from pairs of adjacent passbands within a given set (e.g. Y-J, J-H and H-K for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the point-source colours and extended source colours are computed from the aperture corrected AperMag3 fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands) and generally good signal-to-noise. At some point in the future, this may be changed such that point-source colours will be computed from the PSF-fitted measures and extended source colours computed from the 2-d Sersic model profile fits.
zmyExtErr gcsPointSource, gcsZYJHKsource, reliableGcsPointSource WSA Error on extended source colour Z-Y real 4 mag -0.9999995e9 ERROR
zmyExtErr gcsSource WSA Error on extended source colour Z-Y real 4 mag -0.9999995e9 ERROR
Default colours from pairs of adjacent passbands within a given set (e.g. Y-J, J-H and H-K for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the point-source colours and extended source colours are computed from the aperture corrected AperMag3 fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands) and generally good signal-to-noise. At some point in the future, this may be changed such that point-source colours will be computed from the PSF-fitted measures and extended source colours computed from the 2-d Sersic model profile fits.
zmyPnt calSource, calSynopticSource WSACalib Point source colour Z-Y (using aperMag3) real 4 mag -0.9999995e9 PHOT_COLOR
Default colours from pairs of adjacent passbands within a given set (e.g. Y-J, J-H and H-K for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the point-source colours and extended source colours are computed from the aperture corrected AperMag3 fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands) and generally good signal-to-noise. At some point in the future, this may be changed such that point-source colours will be computed from the PSF-fitted measures and extended source colours computed from the 2-d Sersic model profile fits.
zmyPnt gcsPointSource, gcsZYJHKsource, reliableGcsPointSource WSA Point source colour Z-Y (using aperMag3) real 4 mag -0.9999995e9 PHOT_COLOR
zmyPnt gcsSource WSA Point source colour Z-Y (using aperMag3) real 4 mag -0.9999995e9 PHOT_COLOR
Default colours from pairs of adjacent passbands within a given set (e.g. Y-J, J-H and H-K for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the point-source colours and extended source colours are computed from the aperture corrected AperMag3 fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands) and generally good signal-to-noise. At some point in the future, this may be changed such that point-source colours will be computed from the PSF-fitted measures and extended source colours computed from the 2-d Sersic model profile fits.
zmyPntErr calSource, calSynopticSource WSACalib Error on point source colour Z-Y real 4 mag -0.9999995e9 ERROR
Default colours from pairs of adjacent passbands within a given set (e.g. Y-J, J-H and H-K for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the point-source colours and extended source colours are computed from the aperture corrected AperMag3 fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands) and generally good signal-to-noise. At some point in the future, this may be changed such that point-source colours will be computed from the PSF-fitted measures and extended source colours computed from the 2-d Sersic model profile fits.
zmyPntErr gcsPointSource, gcsZYJHKsource, reliableGcsPointSource WSA Error on point source colour Z-Y real 4 mag -0.9999995e9 ERROR
zmyPntErr gcsSource WSA Error on point source colour Z-Y real 4 mag -0.9999995e9 ERROR
Default colours from pairs of adjacent passbands within a given set (e.g. Y-J, J-H and H-K for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the point-source colours and extended source colours are computed from the aperture corrected AperMag3 fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands) and generally good signal-to-noise. At some point in the future, this may be changed such that point-source colours will be computed from the PSF-fitted measures and extended source colours computed from the 2-d Sersic model profile fits.
zndof calVariability WSACalib Number of degrees of freedom for chisquare smallint 2   -9999  
The photometry is calculated for good observations in the best aperture. The mean, rms, median, median absolute deviation, minMag and maxMag are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. The number of good detections that are more than 3 standard deviations can indicate a distribution with many outliers. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.
znDofAst calVarFrameSetInfo WSACalib Number of degrees of freedom of astrometric fit in Z band. smallint 2   -9999  
The best fit solution to the expected RMS position around the mean for all objects in the frameset. Objects were binned in ranges of magnitude and the median RMS (after clipping out variable objects using the median-absolute deviation) was calculated. The Strateva function $\zeta(m)>=a+b\,10^{0.4m}+c\,10^{0.8m}$ was fit, where $\zeta(m)$ is the expected RMS as a function of magnitude. The chi-squared and number of degrees of freedom are also calculated.
znDofPht calVarFrameSetInfo WSACalib Number of degrees of freedom of photometric fit in Z band. smallint 2   -9999  
The best fit solution to the expected RMS brightness (in magnitudes) for all objects in the frameset. Objects were binned in ranges of magnitude and the median RMS (after clipping out variable objects using the median-absolute deviation) was calculated. The Strateva function $\zeta(m)>=a+b\,10^{0.4m}+c\,10^{0.8m}$ was fit, where $\zeta(m)$ is the expected RMS as a function of magnitude. The chi-squared and number of degrees of freedom are also calculated. This technique was used in Sesar et al. 2007, AJ, 134, 2236.
znFlaggedObs calVariability WSACalib Number of detections in Z band flagged as potentially spurious by calDetection.ppErrBits int 4   0  
The observations are classified as good, flagged or missing. Flagged observations are ones where the object has a ppErrBit flag. Missing observations are observations of the part of the sky that include the position of the object, but had no detection. All the statistics are calculated from good observations. The cadence parameters give the minimum, median and maximum time between observations, which is useful to know if the data could be used to find a particular type of variable.
znFrames StackObjectThin PS1DR2 Number of input frames/exposures contributing to the z filter stack detection. int 4   -999  
znGoodObs calVariability WSACalib Number of good detections in Z band int 4   0  
The observations are classified as good, flagged or missing. Flagged observations are ones where the object has a ppErrBit flag. Missing observations are observations of the part of the sky that include the position of the object, but had no detection. All the statistics are calculated from good observations. The cadence parameters give the minimum, median and maximum time between observations, which is useful to know if the data could be used to find a particular type of variable.
zNgt3sig calVariability WSACalib Number of good detections in Z-band that are more than 3 sigma deviations smallint 2   -9999  
The photometry is calculated for good observations in the best aperture. The mean, rms, median, median absolute deviation, minMag and maxMag are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. The number of good detections that are more than 3 standard deviations can indicate a distribution with many outliers. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.
znMissingObs calVariability WSACalib Number of Z band frames that this object should have been detected on and was not int 4   0  
The observations are classified as good, flagged or missing. Flagged observations are ones where the object has a ppErrBit flag. Missing observations are observations of the part of the sky that include the position of the object, but had no detection. All the statistics are calculated from good observations. The cadence parameters give the minimum, median and maximum time between observations, which is useful to know if the data could be used to find a particular type of variable.
zone ExternalSurveyTable WSA default (0) or special (n) zone smallint 2     obs.field
zone ExternalSurveyTable WSACalib default (0) or special (n) zone smallint 2     obs.field
zone ExternalSurveyTable WSATransit default (0) or special (n) zone smallint 2     obs.field
zone ExternalSurveyTable WSAUHS default (0) or special (n) zone smallint 2     obs.field
zoneID ObjectThin PS1DR2 Local zone index, found by dividing the sky into bands of declination 1/2 arcminute in height: zoneID = floor((90 + declination)/0.0083333). int 4     meta.id
zp Detection PS1DR2 Photometric zeropoint. Necessary for converting listed fluxes and magnitudes back to measured ADU counts. real 4 magnitudes 0  
zPA calSource, calSynopticSource WSACalib ellipse fit celestial orientation in Z real 4 Degrees -0.9999995e9 POS_POS-ANG
zPA gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource WSA ellipse fit celestial orientation in Z real 4 Degrees -0.9999995e9 POS_POS-ANG
zPetroMag calSource WSACalib Extended source Z mag (Petrosian) real 4 mag -0.9999995e9 PHOT_MAG
zPetroMag gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource WSA Extended source Z mag (Petrosian) real 4 mag -0.9999995e9 PHOT_MAG
zPetroMagErr calSource WSACalib Error in extended source Z mag (Petrosian) real 4 mag -0.9999995e9 ERROR
zPetroMagErr gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource WSA Error in extended source Z mag (Petrosian) real 4 mag -0.9999995e9 ERROR
zPhoto twompzPhotoz TWOMPZ Photometric redshift obtained with the ANNz framework {image primary HDU keyword: zphoto} real 4   -0.9999995e9  
zPhoto_ANN wiseScosPhotoz, wiseScosPhotozRejects, wiseScosSvm WISExSCOSPZ Photometric redshift obtained with the ANNz framework {image primary HDU keyword: zAnnz} real 4   -0.9999995e9  
zPhoto_Corr wiseScosPhotoz, wiseScosPhotozRejects, wiseScosSvm WISExSCOSPZ Photometric redshift corrected at dec(1950)>2.5 for a hemispherical offset {image primary HDU keyword: zCorr} real 4   -0.9999995e9  
zPlateScale StackObjectAttributes PS1DR2 Local plate scale for the z filter stack. real 4 arcsec/pixel 0  
zppErrBits calSource, calSynopticSource WSACalib additional WFAU post-processing error bits in Z int 4   0 CODE_MISC
Post-processing error quality bit flags assigned (NB: from UKIDSS DR2 release onwards) in the WSA curation procedure for survey data. From least to most significant byte in the 4-byte integer attribute byte 0 (bits 0 to 7) corresponds to information on generally innocuous conditions that are nonetheless potentially significant as regards the integrity of that detection; byte 1 (bits 8 to 15) corresponds to warnings; byte 2 (bits 16 to 23) corresponds to important warnings; and finally byte 3 (bits 24 to 31) corresponds to severe warnings:
ByteBitDetection quality issue Threshold or bit mask Applies to
DecimalHexadecimal
0 4 Deblended 16 0x00000010 All VDFS catalogues
0 6 Bad pixel(s) in default aperture 64 0x00000040 All VDFS catalogues
1 15 Source in poor flat field region 32768 0x00008000 All but mosaics
2 16 Close to saturated 65536 0x00010000 All VDFS catalogues (though deeps excluded prior to DR8)
2 17 Photometric calibration probably subject to systematic error 131072 0x00020000 GPS only
2 19 Possible crosstalk artefact/contamination 524288 0x00080000 All but GPS
2 22 Lies within a dither offset of the stacked frame boundary 4194304 0x00400000 All but mosaics

In this way, the higher the error quality bit flag value, the more likely it is that the detection is spurious. The decimal threshold (column 4) gives the minimum value of the quality flag for a detection having the given condition (since other bits in the flag may be set also; the corresponding hexadecimal value, where each digit corresponds to 4 bits in the flag, can be easier to compute when writing SQL queries to test for a given condition). For example, to exclude all K band sources in the LAS having any error quality condition other than informational ones, include a predicate ... AND kppErrBits ≤ 255. See the SQL Cookbook and other online pages for further information.
zppErrBits gcsPointSource, gcsZYJHKsource, reliableGcsPointSource WSA additional WFAU post-processing error bits in Z int 4   0 CODE_MISC
zppErrBits gcsSource WSA additional WFAU post-processing error bits in Z int 4   0 CODE_MISC
Post-processing error quality bit flags assigned (NB: from UKIDSS DR2 release onwards) in the WSA curation procedure for survey data. From least to most significant byte in the 4-byte integer attribute byte 0 (bits 0 to 7) corresponds to information on generally innocuous conditions that are nonetheless potentially significant as regards the integrity of that detection; byte 1 (bits 8 to 15) corresponds to warnings; byte 2 (bits 16 to 23) corresponds to important warnings; and finally byte 3 (bits 24 to 31) corresponds to severe warnings:
ByteBitDetection quality issue Threshold or bit mask Applies to
DecimalHexadecimal
0 4 Deblended 16 0x00000010 All VDFS catalogues
0 6 Bad pixel(s) in default aperture 64 0x00000040 All VDFS catalogues
1 15 Source in poor flat field region 32768 0x00008000 All but mosaics
2 16 Close to saturated 65536 0x00010000 All VDFS catalogues (though deeps excluded prior to DR8)
2 17 Photometric calibration probably subject to systematic error 131072 0x00020000 GPS only
2 19 Possible crosstalk artefact/contamination 524288 0x00080000 All but GPS
2 22 Lies within a dither offset of the stacked frame boundary 4194304 0x00400000 All but mosaics

In this way, the higher the error quality bit flag value, the more likely it is that the detection is spurious. The decimal threshold (column 4) gives the minimum value of the quality flag for a detection having the given condition (since other bits in the flag may be set also; the corresponding hexadecimal value, where each digit corresponds to 4 bits in the flag, can be easier to compute when writing SQL queries to test for a given condition). For example, to exclude all K band sources in the LAS having any error quality condition other than informational ones, include a predicate ... AND kppErrBits ≤ 255. See the SQL Cookbook and other online pages for further information.
zprobVar calVariability WSACalib Probability of variable from chi-square (and other data) real 4   -0.9999995e9  
The photometry is calculated for good observations in the best aperture. The mean, rms, median, median absolute deviation, minMag and maxMag are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. The number of good detections that are more than 3 standard deviations can indicate a distribution with many outliers. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.
zpsfChiSq StackObjectAttributes PS1DR2 Reduced chi squared value of the PSF model fit for z filter stack detection. real 4   -999  
zpsfCore StackObjectAttributes PS1DR2 PSF core parameter k from z filter stack detection, where F = F0 / (1 + k r^2 + r^3.33). real 4   -999  
zPSFFlux StackObjectAttributes PS1DR2 PSF flux from z filter stack detection. real 4 Janskys -999  
zPSFFluxErr StackObjectAttributes PS1DR2 Error in PSF flux from z filter stack detection. real 4 Janskys -999  
zpsfLikelihood StackObjectAttributes PS1DR2 Likelihood that this z filter stack detection is best fit by a PSF. real 4   -999  
zPSFMag StackObjectThin PS1DR2 PSF magnitude from z filter stack detection. real 4 AB magnitudes -999  
zPsfMag calSource WSACalib Point source profile-fitted Z mag real 4 mag -0.9999995e9 PHOT_MAG
zPsfMag gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource WSA Point source profile-fitted Z mag real 4 mag -0.9999995e9 PHOT_MAG
zPSFMagErr StackObjectThin PS1DR2 Error in PSF magnitude from z filter stack detection. real 4 AB magnitudes -999  
zPsfMagErr calSource WSACalib Error in point source profile-fitted Z mag real 4 mag -0.9999995e9 ERROR
zPsfMagErr gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource WSA Error in point source profile-fitted Z mag real 4 mag -0.9999995e9 ERROR
zpsfMajorFWHM StackObjectAttributes PS1DR2 PSF major axis FWHM from z filter stack detection. real 4 arcsec -999  
zpsfMinorFWHM StackObjectAttributes PS1DR2 PSF minor axis FWHM from z filter stack detection. real 4 arcsec -999  
zpsfQf StackObjectAttributes PS1DR2 PSF coverage factor for z filter stack detection. real 4   -999  
zpsfQfPerfect StackObjectAttributes PS1DR2 PSF-weighted fraction of pixels totally unmasked for z filter stack detection. real 4   -999  
zpsfTheta StackObjectAttributes PS1DR2 PSF major axis orientation from z filter stack detection. real 4 degrees -999  
zpSystem ExternalProduct WSA System of zeropoint (Vega/AB) varchar 16   'NONE'  
zpSystem ExternalProduct WSAUHS System of zeropoint (Vega/AB) varchar 16   'NONE'  
zpSystem RequiredMosaicTopLevel WSAUHS System of zeropoint (Vega/AB) varchar 8   'NONE'  
zQfPerfect MeanObject PS1DR2 Maximum PSF weighted fraction of pixels totally unmasked from z filter detections. real 4   -999  
zra StackObjectThin PS1DR2 Right ascension from z filter stack detection. float 8 degrees -999  
zraErr StackObjectThin PS1DR2 Right ascension error from z filter stack detection. real 4 arcsec -999  
zSeqNum calSource, calSynopticSource WSACalib the running number of the Z detection int 4   -99999999 ID_NUMBER
zSeqNum gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource WSA the running number of the Z detection int 4   -99999999 ID_NUMBER
zSerMag2D calSource WSACalib Extended source Z mag (profile-fitted) real 4 mag -0.9999995e9 PHOT_MAG
zSerMag2D gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource WSA Extended source Z mag (profile-fitted) real 4 mag -0.9999995e9 PHOT_MAG
zSerMag2DErr calSource WSACalib Error in extended source Z mag (profile-fitted) real 4 mag -0.9999995e9 ERROR
zSerMag2DErr gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource WSA Error in extended source Z mag (profile-fitted) real 4 mag -0.9999995e9 ERROR
zskewness calVariability WSACalib Skewness in Z band (see Sesar et al. 2007) real 4   -0.9999995e9  
The photometry is calculated for good observations in the best aperture. The mean, rms, median, median absolute deviation, minMag and maxMag are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. The number of good detections that are more than 3 standard deviations can indicate a distribution with many outliers. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.
zsky StackObjectAttributes PS1DR2 Residual background sky level at the z filter stack detection. real 4 Janskys/arcsec^2 -999  
zskyErr StackObjectAttributes PS1DR2 Error in residual background sky level at the z filter stack detection. real 4 Janskys/arcsec^2 -999  
ZSOURCE mgcBrightSpec MGC Identifier for best redshift and quality varchar 10      
zSpec twompzPhotoz TWOMPZ Spectroscopic redshift {image primary HDU keyword: zspec} real 4   -0.9999995e9  
zstackDetectID StackObjectAttributes, StackObjectThin PS1DR2 Unique stack detection identifier. bigint 8      
zstackImageID StackObjectAttributes, StackObjectThin PS1DR2 Unique stack identifier for z filter detection. bigint 8      
ztotalPeriod calVariability WSACalib total period of observations (last obs-first obs) real 4 days -0.9999995e9  
The observations are classified as good, flagged or missing. Flagged observations are ones where the object has a ppErrBit flag. Missing observations are observations of the part of the sky that include the position of the object, but had no detection. All the statistics are calculated from good observations. The cadence parameters give the minimum, median and maximum time between observations, which is useful to know if the data could be used to find a particular type of variable.
zVarClass calVariability WSACalib Classification of variability in this band smallint 2   -9999  
The photometry is calculated for good observations in the best aperture. The mean, rms, median, median absolute deviation, minMag and maxMag are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. The number of good detections that are more than 3 standard deviations can indicate a distribution with many outliers. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.
zXi calSource, calSynopticSource WSACalib Offset of Z detection from master position (+east/-west) real 4 arcsec -0.9999995e9 POS_EQ_RA_OFF
When associating individual passband detections into merged sources, a generous (in terms of the positional uncertainties) pairing radius of 2.0 (UKIDSS LAS and GPS; UHS; also non-survey programmes) or 1.0 (UKIDSS GPS, DXS and UDS) arcseconds is used, the higher value enabling pairing of moving sources when epoch separations may be several years. Such a large association criterion can of course lead to spurious pairings in the merged sources lists (although note that between passband pairs, handshake pairing is done: both passbands must agree that the candidate pair is their nearest neighbour for the pair to propagate through into the merged source table). In order to help filter spurious pairings out, and assuming that large positional offsets between the different passband detections are not expected (e.g. because of source motion, or larger than usual positional uncertainties) then the attributes Xi and Eta can be used to filter any pairings with suspiciously large offsets in one or more bands. For example, for a clean sample of QSOs from the LAS, you might wish to insist that the offsets in the selected sample are all below 1 arcsecond: simply add WHERE clauses into the SQL sample selection script to exclude all Xi and Eta values larger than the threshold you want. NB: the master position is the position of the detection in the shortest passband in the set, rather than the ra/dec of the source as stored in source attributes of the same name. The former is used in the pairing process, while the latter is generally the optimally weighted mean position from an astrometric solution or other combinatorial process of all individual detection positions across the available passbands.
zXi gcsPointSource, gcsZYJHKsource, reliableGcsPointSource WSA Offset of Z detection from master position (+east/-west) real 4 arcsec -0.9999995e9 POS_EQ_RA_OFF
zXi gcsSource WSA Offset of Z detection from master position (+east/-west) real 4 arcsec -0.9999995e9 POS_EQ_RA_OFF
When associating individual passband detections into merged sources, a generous (in terms of the positional uncertainties) pairing radius of 2.0 (UKIDSS LAS and GPS; UHS; also non-survey programmes) or 1.0 (UKIDSS GPS, DXS and UDS) arcseconds is used, the higher value enabling pairing of moving sources when epoch separations may be several years. Such a large association criterion can of course lead to spurious pairings in the merged sources lists (although note that between passband pairs, handshake pairing is done: both passbands must agree that the candidate pair is their nearest neighbour for the pair to propagate through into the merged source table). In order to help filter spurious pairings out, and assuming that large positional offsets between the different passband detections are not expected (e.g. because of source motion, or larger than usual positional uncertainties) then the attributes Xi and Eta can be used to filter any pairings with suspiciously large offsets in one or more bands. For example, for a clean sample of QSOs from the LAS, you might wish to insist that the offsets in the selected sample are all below 1 arcsecond: simply add WHERE clauses into the SQL sample selection script to exclude all Xi and Eta values larger than the threshold you want. NB: the master position is the position of the detection in the shortest passband in the set, rather than the ra/dec of the source as stored in source attributes of the same name. The former is used in the pairing process, while the latter is generally the optimally weighted mean position from an astrometric solution or other combinatorial process of all individual detection positions across the available passbands.
zxPos StackObjectAttributes PS1DR2 PSF x center location from z filter stack detection. real 4 sky pixels -999  
zxPosErr StackObjectAttributes PS1DR2 Error in PSF x center location from z filter stack detection. real 4 sky pixels -999  
zyiWS calVariability WSACalib Welch-Stetson statistic between Z and Y. This assumes colour does not vary much and helps remove variation due to a few poor detections real 4   -0.9999995e9  
The Welch-Stetson statistic is a measure of the correlation of the variability between two bands. We use the calculation in Welch D.L. and Stetson P.B. 1993, AJ, 105, 5, which is also used in Sesar et al. 2007, AJ, 134, 2236. We use the aperMag3 magnitude when comparing between bands.
zyPos StackObjectAttributes PS1DR2 PSF y center location from z filter stack detection. real 4 sky pixels -999  
zyPosErr StackObjectAttributes PS1DR2 Error in PSF y center location from z filter stack detection. real 4 sky pixels -999  
zzp StackObjectAttributes PS1DR2 Photometric zeropoint for the z filter stack. Necessary for converting listed fluxes and magnitudes back to measured ADU counts. real 4 magnitudes 0  



Home | Overview | Browser | Access | Login | Cookbook | nonSurvey
Listing | Region | MenuQuery | FreeSQL
Links | Credits

WFAU, Institute for Astronomy,
Royal Observatory, Blackford Hill
Edinburgh, EH9 3HJ, UK

wsa-support@roe.ac.uk
17/01/2022