Y 
Name  Schema Table  Database  Description  Type  Length  Unit  Default Value  Unified Content Descriptor 
y 
UKIDSSDetection 
WSA 
Y coordinate of detection 
real 
4 
pixels 

POS_PLATE_Y 
y 
allwise_sc2 
WISE 
Unit sphere position y value 
float 
8 



y 
calDetection 
WSACalib 
Y coordinate of detection {catalogue TType keyword: Y_coordinate} Intensityweighted isophotal centreofgravity in Y. 
real 
4 
pixels 

POS_PLATE_Y 
y 
dxsDetection, gcsDetection, gpsDetection, lasDetection 
WSA 
Y coordinate of detection {catalogue TType keyword: Y_coordinate} Intensityweighted isophotal centreofgravity in Y. 
real 
4 
pixels 

POS_PLATE_Y 
y 
ptsDetection 
WSATransit 
Y coordinate of detection {catalogue TType keyword: Y_coordinate} Intensityweighted isophotal centreofgravity in Y. 
real 
4 
pixels 

POS_PLATE_Y 
y 
udsDetection 
WSA 
Y coordinate of detection (SE: Y_IMAGE) {catalogue TType keyword: Y_coordinate} Intensityweighted isophotal centreofgravity in Y. 
real 
4 
pixels 

POS_PLATE_Y 
y 
uhsDetection, uhsDetectionAll 
WSAUHS 
Y coordinate of detection {catalogue TType keyword: Y_coordinate} Intensityweighted isophotal centreofgravity in Y. 
real 
4 
pixels 

POS_PLATE_Y 
y_coadd 
twomass_xsc 
2MASS 
y (inscan) position (coadd coord.). 
real 
4 
arcsec 

INST_POS 
Y_IMAGE 
mgcDetection 
MGC 
Object y position 
real 
4 
pixel 


Y_OFF 
mgcGalaxyStruct 
MGC 
Y offset of Galaxy Centre 
real 
4 

99.99 

Y_OFFm 
mgcGalaxyStruct 
MGC 
Y offset error () 
real 
4 

99.99 

Y_OFFp 
mgcGalaxyStruct 
MGC 
Y offset error (+) 
real 
4 

99.99 

yAperMag1 
calSynopticSource 
WSACalib 
Extended source Y aperture corrected mag (1.0 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
yAperMag1Err 
calSynopticSource 
WSACalib 
Error in extended source Y mag (1.0 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
ERROR 
yAperMag2 
calSynopticSource 
WSACalib 
Extended source Y aperture corrected mag (1.4 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
yAperMag2Err 
calSynopticSource 
WSACalib 
Error in extended source Y mag (1.4 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
ERROR 
yAperMag3 
calSource 
WSACalib 
Default point/extended source Y aperture corrected mag (2.0 arcsec aperture diameter) If in doubt use this flux estimator 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
yAperMag3 
calSynopticSource 
WSACalib 
Default point/extended source Y aperture corrected mag (2.0 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
yAperMag3 
gcsPointSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
Default point source Y aperture corrected mag (2.0 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
yAperMag3 
gcsSource, lasSource 
WSA 
Default point source Y aperture corrected mag (2.0 arcsec aperture diameter) If in doubt use this flux estimator 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
yAperMag3Err 
calSource, calSynopticSource 
WSACalib 
Error in default point/extended source Y mag (2.0 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
ERROR 
yAperMag3Err 
gcsPointSource, gcsSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
Error in default point source Y mag (2.0 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
ERROR 
yAperMag4 
calSource, calSynopticSource 
WSACalib 
Extended source Y aperture corrected mag (2.8 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
yAperMag4 
gcsPointSource, gcsSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
Point source Y aperture corrected mag (2.8 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
yAperMag4Err 
calSource, calSynopticSource 
WSACalib 
Error in extended source Y mag (2.8 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
ERROR 
yAperMag4Err 
gcsPointSource, gcsSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
Error in point source Y mag (2.8 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
ERROR 
yAperMag5 
calSynopticSource 
WSACalib 
Extended source Y aperture corrected mag (4.0 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
yAperMag5Err 
calSynopticSource 
WSACalib 
Error in extended source Y mag (4.0 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
ERROR 
yAperMag6 
calSource 
WSACalib 
Extended source Y aperture corrected mag (5.7 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
yAperMag6 
gcsPointSource, gcsSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
Point source Y aperture corrected mag (5.7 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
yAperMag6Err 
calSource 
WSACalib 
Error in extended source Y mag (5.7 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
ERROR 
yAperMag6Err 
gcsPointSource, gcsSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
Error in point source Y mag (5.7 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
ERROR 
yaStratAst 
calVarFrameSetInfo 
WSACalib 
Strateva parameter, a, in fit to astrometric rms vs magnitude in Y 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 medianabsolute 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 chisquared and number of degrees of freedom are also calculated. 
yaStratPht 
calVarFrameSetInfo 
WSACalib 
Strateva parameter, a, in fit to photometric rms vs magnitude in Y 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 medianabsolute 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 chisquared and number of degrees of freedom are also calculated. This technique was used in Sesar et al. 2007, AJ, 134, 2236. 
ybestAper 
calVariability 
WSACalib 
Best aperture (16) for photometric statistics in the Y band 
int 
4 

9999 

Aperture magnitude (16) 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) 
ybStratAst 
calVarFrameSetInfo 
WSACalib 
Strateva parameter, b, in fit to astrometric rms vs magnitude in Y 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 medianabsolute 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 chisquared and number of degrees of freedom are also calculated. 
ybStratPht 
calVarFrameSetInfo 
WSACalib 
Strateva parameter, b, in fit to photometric rms vs magnitude in Y 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 medianabsolute 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 chisquared and number of degrees of freedom are also calculated. This technique was used in Sesar et al. 2007, AJ, 134, 2236. 
ychiSqAst 
calVarFrameSetInfo 
WSACalib 
Goodness of fit of Strateva function to astrometric data in Y 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 medianabsolute 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 chisquared and number of degrees of freedom are also calculated. 
ychiSqpd 
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 chisquared is calculated, assuming a nonvariable object which has the noise from the expectedrms and mean calculated as above. The probVar statistic assumes a chisquared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3. 
ychiSqPht 
calVarFrameSetInfo 
WSACalib 
Goodness of fit of Strateva function to photometric data in Y 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 medianabsolute 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 chisquared and number of degrees of freedom are also calculated. This technique was used in Sesar et al. 2007, AJ, 134, 2236. 
yClass 
calSource, calSynopticSource 
WSACalib 
discrete image classification flag in Y 
smallint 
2 

9999 
CLASS_MISC 
yClass 
gcsPointSource, gcsSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
discrete image classification flag in Y 
smallint 
2 

9999 
CLASS_MISC 
yClassStat 
calSource, calSynopticSource 
WSACalib 
N(0,1) stellarnessofprofile statistic in Y 
real 
4 

0.9999995e9 
STAT_PROP 
yClassStat 
gcsPointSource, gcsSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
N(0,1) stellarnessofprofile statistic in Y 
real 
4 

0.9999995e9 
STAT_PROP 
ycStratAst 
calVarFrameSetInfo 
WSACalib 
Strateva parameter, c, in fit to astrometric rms vs magnitude in Y 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 medianabsolute 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 chisquared and number of degrees of freedom are also calculated. 
ycStratPht 
calVarFrameSetInfo 
WSACalib 
Strateva parameter, c, in fit to photometric rms vs magnitude in Y 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 medianabsolute 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 chisquared and number of degrees of freedom are also calculated. This technique was used in Sesar et al. 2007, AJ, 134, 2236. 
yDeblend 
calSource 
WSACalib 
placeholder flag indicating parent/child relation in Y 
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 postprocessing software based on testing the areal profiles aprof28 (these are set by CASU to 1 for deblended components, or positive values for nondeblended detections). We encode this in an information bit of ppErrBits for convenience when querying the merged source tables. 
yDeblend 
calSynopticSource 
WSACalib 
placeholder flag indicating parent/child relation in Y 
int 
4 

99999999 
CODE_MISC 
yDeblend 
gcsPointSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
placeholder flag indicating parent/child relation in Y 
int 
4 

99999999 
CODE_MISC 
yDeblend 
gcsSource, lasSource 
WSA 
placeholder flag indicating parent/child relation in Y 
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 postprocessing software based on testing the areal profiles aprof28 (these are set by CASU to 1 for deblended components, or positive values for nondeblended detections). We encode this in an information bit of ppErrBits for convenience when querying the merged source tables. 
yEll 
calSource, calSynopticSource 
WSACalib 
1b/a, where a/b=semimajor/minor axes in Y 
real 
4 

0.9999995e9 
PHYS_ELLIPTICITY 
yEll 
gcsPointSource, gcsSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
1b/a, where a/b=semimajor/minor axes in Y 
real 
4 

0.9999995e9 
PHYS_ELLIPTICITY 
yeNum 
calMergeLog, calSynopticMergeLog 
WSACalib 
the extension number of this Y frame 
tinyint 
1 


NUMBER 
yeNum 
gcsMergeLog, gcsZYJHKmergeLog, lasMergeLog 
WSA 
the extension number of this Y frame 
tinyint 
1 


NUMBER 
yeNum 
lasYJHKmergeLog 
WSA 
the extension number of this frame 
tinyint 
1 


NUMBER 
yErr 
UKIDSSDetection 
WSA 
Error in Y coordinate 
real 
4 
pixels 

ERROR 
yErr 
calDetection 
WSACalib 
Error in Y coordinate {catalogue TType keyword: Y_coordinate_err} Estimate of centroid error. 
real 
4 
pixels 

ERROR 
yErr 
dxsDetection, gcsDetection, gpsDetection, lasDetection 
WSA 
Error in Y coordinate {catalogue TType keyword: Y_coordinate_err} Estimate of centroid error. 
real 
4 
pixels 

ERROR 
yErr 
ptsDetection 
WSATransit 
Error in Y coordinate {catalogue TType keyword: Y_coordinate_err} Estimate of centroid error. 
real 
4 
pixels 

ERROR 
yErr 
udsDetection 
WSA 
Error in Y coordinate (SE: ERRY2_IMAGE^{½}) {catalogue TType keyword: Y_coordinate_err} Estimate of centroid error. 
real 
4 
pixels 

ERROR 
yErr 
uhsDetection, uhsDetectionAll 
WSAUHS 
Error in Y coordinate {catalogue TType keyword: Y_coordinate_err} Estimate of centroid error. 
real 
4 
pixels 

ERROR 
yErrBits 
calSource, calSynopticSource 
WSACalib 
processing warning/error bitwise flags in Y 
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. 
yErrBits 
gcsPointSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
processing warning/error bitwise flags in Y 
int 
4 

99999999 
CODE_MISC 
yErrBits 
gcsSource, lasSource 
WSA 
processing warning/error bitwise flags in Y 
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. 
yEta 
calSource, calSynopticSource 
WSACalib 
Offset of Y 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 nonsurvey 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. 
yEta 
gcsPointSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
Offset of Y detection from master position (+north/south) 
real 
4 
arcsec 
0.9999995e9 
POS_EQ_DEC_OFF 
yEta 
gcsSource, lasSource 
WSA 
Offset of Y 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 nonsurvey 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. 
yexpML 
calVarFrameSetInfo 
WSACalib 
Expected magnitude limit of frameSet in this in Y 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. 
yExpRms 
calVariability 
WSACalib 
Rms calculated from polynomial fit to modal RMS as a function of magnitude in Y 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 chisquared is calculated, assuming a nonvariable object which has the noise from the expectedrms and mean calculated as above. The probVar statistic assumes a chisquared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3. 
yGausig 
calSource, calSynopticSource 
WSACalib 
RMS of axes of ellipse fit in Y 
real 
4 
pixels 
0.9999995e9 
MORPH_PARAM 
yGausig 
gcsPointSource, gcsSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
RMS of axes of ellipse fit in Y 
real 
4 
pixels 
0.9999995e9 
MORPH_PARAM 
yHallMag 
calSource 
WSACalib 
Total point source Y mag 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
yHallMag 
gcsPointSource, gcsSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
Total point source Y mag 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
yHallMagErr 
calSource 
WSACalib 
Error in total point source Y mag 
real 
4 
mag 
0.9999995e9 
ERROR 
yHallMagErr 
gcsPointSource, gcsSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
Error in total point source Y mag 
real 
4 
mag 
0.9999995e9 
ERROR 
yIntRms 
calVariability 
WSACalib 
Intrinsic rms in Yband 
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 chisquared is calculated, assuming a nonvariable object which has the noise from the expectedrms and mean calculated as above. The probVar statistic assumes a chisquared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3. 
yisDefAst 
calVarFrameSetInfo 
WSACalib 
Use a default model for the astrometric noise in Y band. 
tinyint 
1 

0 

yisDefPht 
calVarFrameSetInfo 
WSACalib 
Use a default model for the photometric noise in Y band. 
tinyint 
1 

0 

yjiWS 
calVariability 
WSACalib 
WelchStetson statistic between Y and J. This assumes colour does not vary much and helps remove variation due to a few poor detections 
real 
4 

0.9999995e9 

The WelchStetson 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. 
yMagMAD 
calVariability 
WSACalib 
Median Absolute Deviation of Y 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 chisquared is calculated, assuming a nonvariable object which has the noise from the expectedrms and mean calculated as above. The probVar statistic assumes a chisquared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3. 
yMagRms 
calVariability 
WSACalib 
rms of Y 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 chisquared is calculated, assuming a nonvariable object which has the noise from the expectedrms and mean calculated as above. The probVar statistic assumes a chisquared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3. 
ymaxCadence 
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. 
yMaxMag 
calVariability 
WSACalib 
Maximum magnitude in Y 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 chisquared is calculated, assuming a nonvariable object which has the noise from the expectedrms and mean calculated as above. The probVar statistic assumes a chisquared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3. 
ymeanMag 
calVariability 
WSACalib 
Mean Y 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 chisquared is calculated, assuming a nonvariable object which has the noise from the expectedrms and mean calculated as above. The probVar statistic assumes a chisquared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3. 
ymedCadence 
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. 
ymedianMag 
calVariability 
WSACalib 
Median Y 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 chisquared is calculated, assuming a nonvariable object which has the noise from the expectedrms and mean calculated as above. The probVar statistic assumes a chisquared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3. 
ymfID 
calMergeLog, calSynopticMergeLog 
WSACalib 
the UID of the relevant Y multiframe 
bigint 
8 


ID_FRAME 
ymfID 
gcsMergeLog, gcsZYJHKmergeLog, lasMergeLog 
WSA 
the UID of the relevant Y multiframe 
bigint 
8 


ID_FRAME 
ymfID 
lasYJHKmergeLog 
WSA 
the UID of the relevant multiframe 
bigint 
8 


ID_FRAME 
yminCadence 
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. 
yMinMag 
calVariability 
WSACalib 
Minimum magnitude in Y 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 chisquared is calculated, assuming a nonvariable object which has the noise from the expectedrms and mean calculated as above. The probVar statistic assumes a chisquared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3. 
ymj_1Ext 
lasExtendedSource, lasPointSource, lasYJHKsource, reliableLasPointSource 
WSA 
Extended source colour YJ_1 (using aperMag3) 
real 
4 
mag 
0.9999995e9 
PHOT_COLOR 
ymj_1Ext 
lasSource 
WSA 
Extended source colour YJ_1 (using aperMag3) 
real 
4 
mag 
0.9999995e9 
PHOT_COLOR 
Default colours from pairs of adjacent passbands within a given set (e.g. YJ, JH and HK for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the pointsource 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 signaltonoise. At some point in the future, this may be changed such that pointsource colours will be computed from the PSFfitted measures and extended source colours computed from the 2d Sersic model profile fits. 
ymj_1ExtErr 
lasExtendedSource, lasPointSource, lasYJHKsource, reliableLasPointSource 
WSA 
Error on extended source colour YJ_1 
real 
4 
mag 
0.9999995e9 
ERROR 
ymj_1ExtErr 
lasSource 
WSA 
Error on extended source colour YJ_1 
real 
4 
mag 
0.9999995e9 
ERROR 
Default colours from pairs of adjacent passbands within a given set (e.g. YJ, JH and HK for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the pointsource 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 signaltonoise. At some point in the future, this may be changed such that pointsource colours will be computed from the PSFfitted measures and extended source colours computed from the 2d Sersic model profile fits. 
ymj_1Pnt 
lasExtendedSource, lasPointSource, lasYJHKsource, reliableLasPointSource 
WSA 
Point source colour YJ_1 (using aperMag3) 
real 
4 
mag 
0.9999995e9 
PHOT_COLOR 
ymj_1Pnt 
lasSource 
WSA 
Point source colour YJ_1 (using aperMag3) 
real 
4 
mag 
0.9999995e9 
PHOT_COLOR 
Default colours from pairs of adjacent passbands within a given set (e.g. YJ, JH and HK for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the pointsource 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 signaltonoise. At some point in the future, this may be changed such that pointsource colours will be computed from the PSFfitted measures and extended source colours computed from the 2d Sersic model profile fits. 
ymj_1PntErr 
lasExtendedSource, lasPointSource, lasYJHKsource, reliableLasPointSource 
WSA 
Error on point source colour YJ_1 
real 
4 
mag 
0.9999995e9 
ERROR 
ymj_1PntErr 
lasSource 
WSA 
Error on point source colour YJ_1 
real 
4 
mag 
0.9999995e9 
ERROR 
Default colours from pairs of adjacent passbands within a given set (e.g. YJ, JH and HK for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the pointsource 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 signaltonoise. At some point in the future, this may be changed such that pointsource colours will be computed from the PSFfitted measures and extended source colours computed from the 2d Sersic model profile fits. 
ymj_2Ext 
lasExtendedSource, lasPointSource, lasYJHKsource, reliableLasPointSource 
WSA 
Extended source colour YJ_2 (using aperMag3) 
real 
4 
mag 
0.9999995e9 
PHOT_COLOR 
ymj_2Ext 
lasSource 
WSA 
Extended source colour YJ_2 (using aperMag3) 
real 
4 
mag 
0.9999995e9 
PHOT_COLOR 
Default colours from pairs of adjacent passbands within a given set (e.g. YJ, JH and HK for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the pointsource 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 signaltonoise. At some point in the future, this may be changed such that pointsource colours will be computed from the PSFfitted measures and extended source colours computed from the 2d Sersic model profile fits. 
ymj_2ExtErr 
lasExtendedSource, lasPointSource, lasYJHKsource, reliableLasPointSource 
WSA 
Error on extended source colour YJ_2 
real 
4 
mag 
0.9999995e9 
ERROR 
ymj_2ExtErr 
lasSource 
WSA 
Error on extended source colour YJ_2 
real 
4 
mag 
0.9999995e9 
ERROR 
Default colours from pairs of adjacent passbands within a given set (e.g. YJ, JH and HK for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the pointsource 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 signaltonoise. At some point in the future, this may be changed such that pointsource colours will be computed from the PSFfitted measures and extended source colours computed from the 2d Sersic model profile fits. 
ymj_2Pnt 
lasExtendedSource, lasPointSource, lasYJHKsource, reliableLasPointSource 
WSA 
Point source colour YJ_2 (using aperMag3) 
real 
4 
mag 
0.9999995e9 
PHOT_COLOR 
ymj_2Pnt 
lasSource 
WSA 
Point source colour YJ_2 (using aperMag3) 
real 
4 
mag 
0.9999995e9 
PHOT_COLOR 
Default colours from pairs of adjacent passbands within a given set (e.g. YJ, JH and HK for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the pointsource 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 signaltonoise. At some point in the future, this may be changed such that pointsource colours will be computed from the PSFfitted measures and extended source colours computed from the 2d Sersic model profile fits. 
ymj_2PntErr 
lasExtendedSource, lasPointSource, lasYJHKsource, reliableLasPointSource 
WSA 
Error on point source colour YJ_2 
real 
4 
mag 
0.9999995e9 
ERROR 
ymj_2PntErr 
lasSource 
WSA 
Error on point source colour YJ_2 
real 
4 
mag 
0.9999995e9 
ERROR 
Default colours from pairs of adjacent passbands within a given set (e.g. YJ, JH and HK for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the pointsource 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 signaltonoise. At some point in the future, this may be changed such that pointsource colours will be computed from the PSFfitted measures and extended source colours computed from the 2d Sersic model profile fits. 
ymjExt 
calSource 
WSACalib 
Extended source colour YJ (using aperMag3) 
real 
4 
mag 
0.9999995e9 
PHOT_COLOR 
Default colours from pairs of adjacent passbands within a given set (e.g. YJ, JH and HK for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the pointsource 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 signaltonoise. At some point in the future, this may be changed such that pointsource colours will be computed from the PSFfitted measures and extended source colours computed from the 2d Sersic model profile fits. 
ymjExt 
gcsPointSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
Extended source colour YJ (using aperMag3) 
real 
4 
mag 
0.9999995e9 
PHOT_COLOR 
ymjExt 
gcsSource, lasSource 
WSA 
Extended source colour YJ (using aperMag3) 
real 
4 
mag 
0.9999995e9 
PHOT_COLOR 
Default colours from pairs of adjacent passbands within a given set (e.g. YJ, JH and HK for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the pointsource 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 signaltonoise. At some point in the future, this may be changed such that pointsource colours will be computed from the PSFfitted measures and extended source colours computed from the 2d Sersic model profile fits. 
ymjExtErr 
calSource 
WSACalib 
Error on extended source colour YJ 
real 
4 
mag 
0.9999995e9 
ERROR 
Default colours from pairs of adjacent passbands within a given set (e.g. YJ, JH and HK for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the pointsource 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 signaltonoise. At some point in the future, this may be changed such that pointsource colours will be computed from the PSFfitted measures and extended source colours computed from the 2d Sersic model profile fits. 
ymjExtErr 
gcsPointSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
Error on extended source colour YJ 
real 
4 
mag 
0.9999995e9 
ERROR 
ymjExtErr 
gcsSource, lasSource 
WSA 
Error on extended source colour YJ 
real 
4 
mag 
0.9999995e9 
ERROR 
Default colours from pairs of adjacent passbands within a given set (e.g. YJ, JH and HK for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the pointsource 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 signaltonoise. At some point in the future, this may be changed such that pointsource colours will be computed from the PSFfitted measures and extended source colours computed from the 2d Sersic model profile fits. 
ymjPnt 
calSource, calSynopticSource 
WSACalib 
Point source colour YJ (using aperMag3) 
real 
4 
mag 
0.9999995e9 
PHOT_COLOR 
Default colours from pairs of adjacent passbands within a given set (e.g. YJ, JH and HK for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the pointsource 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 signaltonoise. At some point in the future, this may be changed such that pointsource colours will be computed from the PSFfitted measures and extended source colours computed from the 2d Sersic model profile fits. 
ymjPnt 
gcsPointSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
Point source colour YJ (using aperMag3) 
real 
4 
mag 
0.9999995e9 
PHOT_COLOR 
ymjPnt 
gcsSource, lasSource 
WSA 
Point source colour YJ (using aperMag3) 
real 
4 
mag 
0.9999995e9 
PHOT_COLOR 
Default colours from pairs of adjacent passbands within a given set (e.g. YJ, JH and HK for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the pointsource 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 signaltonoise. At some point in the future, this may be changed such that pointsource colours will be computed from the PSFfitted measures and extended source colours computed from the 2d Sersic model profile fits. 
ymjPntErr 
calSource, calSynopticSource 
WSACalib 
Error on point source colour YJ 
real 
4 
mag 
0.9999995e9 
ERROR 
Default colours from pairs of adjacent passbands within a given set (e.g. YJ, JH and HK for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the pointsource 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 signaltonoise. At some point in the future, this may be changed such that pointsource colours will be computed from the PSFfitted measures and extended source colours computed from the 2d Sersic model profile fits. 
ymjPntErr 
gcsPointSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
Error on point source colour YJ 
real 
4 
mag 
0.9999995e9 
ERROR 
ymjPntErr 
gcsSource, lasSource 
WSA 
Error on point source colour YJ 
real 
4 
mag 
0.9999995e9 
ERROR 
Default colours from pairs of adjacent passbands within a given set (e.g. YJ, JH and HK for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the pointsource 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 signaltonoise. At some point in the future, this may be changed such that pointsource colours will be computed from the PSFfitted measures and extended source colours computed from the 2d Sersic model profile fits. 
yndof 
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 chisquared is calculated, assuming a nonvariable object which has the noise from the expectedrms and mean calculated as above. The probVar statistic assumes a chisquared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3. 
ynDofAst 
calVarFrameSetInfo 
WSACalib 
Number of degrees of freedom of astrometric fit in Y 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 medianabsolute 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 chisquared and number of degrees of freedom are also calculated. 
ynDofPht 
calVarFrameSetInfo 
WSACalib 
Number of degrees of freedom of photometric fit in Y 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 medianabsolute 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 chisquared and number of degrees of freedom are also calculated. This technique was used in Sesar et al. 2007, AJ, 134, 2236. 
ynFlaggedObs 
calVariability 
WSACalib 
Number of detections in Y 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. 
ynGoodObs 
calVariability 
WSACalib 
Number of good detections in Y 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. 
yNgt3sig 
calVariability 
WSACalib 
Number of good detections in Yband 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 chisquared is calculated, assuming a nonvariable object which has the noise from the expectedrms and mean calculated as above. The probVar statistic assumes a chisquared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3. 
ynMissingObs 
calVariability 
WSACalib 
Number of Y 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. 
yPA 
calSource, calSynopticSource 
WSACalib 
ellipse fit celestial orientation in Y 
real 
4 
Degrees 
0.9999995e9 
POS_POSANG 
yPA 
gcsPointSource, gcsSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
ellipse fit celestial orientation in Y 
real 
4 
Degrees 
0.9999995e9 
POS_POSANG 
yPetroMag 
calSource 
WSACalib 
Extended source Y mag (Petrosian) 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
yPetroMag 
gcsPointSource, gcsSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
Extended source Y mag (Petrosian) 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
yPetroMagErr 
calSource 
WSACalib 
Error in extended source Y mag (Petrosian) 
real 
4 
mag 
0.9999995e9 
ERROR 
yPetroMagErr 
gcsPointSource, gcsSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
Error in extended source Y mag (Petrosian) 
real 
4 
mag 
0.9999995e9 
ERROR 
yPixSize 
CurrentAstrometry 
WSACalib 
Angular size of pixels in Y 
real 
4 
Arcseconds 
0.9999995e9 
pos.angDistance 
yPixSize 
CurrentAstrometry 
WSATransit 
Angular size of pixels in Y 
real 
4 
Arcseconds 
0.9999995e9 
pos.angDistance 
yPixSize 
CurrentAstrometry 
WSAUHS 
Angular size of pixels in Y 
real 
4 
Arcseconds 
0.9999995e9 
pos.angDistance 
yPixSize 
CurrentAstrometry, PreviousAstrometry 
WSA 
Angular size of pixels in Y 
real 
4 
Arcseconds 
0.9999995e9 
pos.angDistance 
yPos 
nvssSource 
NVSS 
Y position (Dec direction) of the radio source 
real 
4 
pixels 

POS_CCD_Y 
yppErrBits 
calSource, calSynopticSource 
WSACalib 
additional WFAU postprocessing error bits in Y 
int 
4 

0 
CODE_MISC 
Postprocessing 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 4byte 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: Byte  Bit  Detection quality issue  Threshold or bit mask  Applies to     Decimal  Hexadecimal   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. 
yppErrBits 
gcsPointSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
additional WFAU postprocessing error bits in Y 
int 
4 

0 
CODE_MISC 
yppErrBits 
gcsSource, lasSource 
WSA 
additional WFAU postprocessing error bits in Y 
int 
4 

0 
CODE_MISC 
Postprocessing 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 4byte 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: Byte  Bit  Detection quality issue  Threshold or bit mask  Applies to     Decimal  Hexadecimal   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. 
yprobVar 
calVariability 
WSACalib 
Probability of variable from chisquare (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 chisquared is calculated, assuming a nonvariable object which has the noise from the expectedrms and mean calculated as above. The probVar statistic assumes a chisquared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3. 
yPsfMag 
calSource 
WSACalib 
Point source profilefitted Y mag 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
yPsfMag 
gcsPointSource, gcsSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
Point source profilefitted Y mag 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
yPsfMagErr 
calSource 
WSACalib 
Error in point source profilefitted Y mag 
real 
4 
mag 
0.9999995e9 
ERROR 
yPsfMagErr 
gcsPointSource, gcsSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
Error in point source profilefitted Y mag 
real 
4 
mag 
0.9999995e9 
ERROR 
ySeqNum 
calSource, calSynopticSource 
WSACalib 
the running number of the Y detection 
int 
4 

99999999 
ID_NUMBER 
ySeqNum 
gcsPointSource, gcsSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
the running number of the Y detection 
int 
4 

99999999 
ID_NUMBER 
ySerMag2D 
calSource 
WSACalib 
Extended source Y mag (profilefitted) 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
ySerMag2D 
gcsPointSource, gcsSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
Extended source Y mag (profilefitted) 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
ySerMag2DErr 
calSource 
WSACalib 
Error in extended source Y mag (profilefitted) 
real 
4 
mag 
0.9999995e9 
ERROR 
ySerMag2DErr 
gcsPointSource, gcsSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
Error in extended source Y mag (profilefitted) 
real 
4 
mag 
0.9999995e9 
ERROR 
ySize 
MultiframeDetector 
WSA 
Corresponding image size (Y); value only available if catalogue file exists {catalogue extension keyword: NYOUT} 
int 
4 

99999999 
meta.number 
ySize 
MultiframeDetector 
WSACalib 
Corresponding image size (Y); value only available if catalogue file exists {catalogue extension keyword: NYOUT} 
int 
4 

99999999 
meta.number 
ySize 
MultiframeDetector 
WSATransit 
Corresponding image size (Y); value only available if catalogue file exists {catalogue extension keyword: NYOUT} 
int 
4 

99999999 
meta.number 
ySize 
MultiframeDetector 
WSAUHS 
Corresponding image size (Y); value only available if catalogue file exists {catalogue extension keyword: NYOUT} 
int 
4 

99999999 
meta.number 
yskewness 
calVariability 
WSACalib 
Skewness in Y 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 chisquared is calculated, assuming a nonvariable object which has the noise from the expectedrms and mean calculated as above. The probVar statistic assumes a chisquared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3. 
ytotalPeriod 
calVariability 
WSACalib 
total period of observations (last obsfirst 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. 
yVarClass 
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 chisquared is calculated, assuming a nonvariable object which has the noise from the expectedrms and mean calculated as above. The probVar statistic assumes a chisquared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3. 
yXi 
calSource, calSynopticSource 
WSACalib 
Offset of Y 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 nonsurvey 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. 
yXi 
gcsPointSource, gcsZYJHKsource, lasExtendedSource, lasPointSource, lasYJHKsource, reliableGcsPointSource, reliableLasPointSource 
WSA 
Offset of Y detection from master position (+east/west) 
real 
4 
arcsec 
0.9999995e9 
POS_EQ_RA_OFF 
yXi 
gcsSource, lasSource 
WSA 
Offset of Y 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 nonsurvey 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. 