B 
Name  Schema Table  Database  Description  Type  Length  Unit  Default Value  Unified Content Descriptor 
b 
[nspid]CurrentAstrometry, [nspid]PreviousAstrometry 
WSA NonSurvey 
Galactic latitude of device centre 
float 
8 
Degrees 

pos.galactic.lat 
b 
[nspid]Detection, [nspid]DxsSource, [nspid]ExtendedSource, [nspid]GcsPointSource, [nspid]GpsPointSource, [nspid]JHKsource, [nspid]JKsource, [nspid]LasPointSource, [nspid]PointSource, [nspid]Source, [nspid]SynopticSource, [nspid]UKIDSSDetection, [nspid]UdsSource, [nspid]YJHKsource, [nspid]ZYJHKsource 
WSA NonSurvey 
Galactic latitude 
float 
8 
Degrees 

POS_GAL_LAT 
b 
[nspid]MapRemeasAver, [nspid]MapRemeasurement 
WSA NonSurvey 
Galactic latitude 
float 
8 
Degrees 

pos.galactic.lat 
bandMergingCriterion 
[nspid]Programme 
WSA NonSurvey 
maximum timespan over which different filters are merged into sources in the synoptic source table. 
real 
4 
minutes 
0.9999995e9 

beamNS 
[nspid]Multiframe 
WSA NonSurvey 
Topend: NS beam {image primary HDU keyword: NSBEAM} 
real 
4 

0.9999995e9 

beamWE 
[nspid]Multiframe 
WSA NonSurvey 
Topend: WE beam {image primary HDU keyword: WEBEAM} 
real 
4 

0.9999995e9 

bitsPerPix 
[nspid]MultiframeDetector 
WSA NonSurvey 
Number of bits per data pixel, eg. +32 = 4 byte integers {image extension keyword: BITPIX} 
smallint 
2 
FITS bitpix 

meta.number 
bMag 
[nspid]FSstars 
WSA NonSurvey 
B band total magnitude 
real 
4 
mag 
0.9999995e9 
phot.mag 
brAperMag1 
[nspid]SynopticSource 
WSA NonSurvey 
Extended source Br aperture corrected mag (1.0 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
brAperMag1Err 
[nspid]SynopticSource 
WSA NonSurvey 
Error in extended source Br mag (1.0 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
ERROR 
brAperMag2 
[nspid]SynopticSource 
WSA NonSurvey 
Extended source Br aperture corrected mag (1.4 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
brAperMag2Err 
[nspid]SynopticSource 
WSA NonSurvey 
Error in extended source Br mag (1.4 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
ERROR 
brAperMag3 
[nspid]Source 
WSA NonSurvey 
Default point source Br aperture corrected mag (2.0 arcsec aperture diameter) If in doubt use this flux estimator 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
brAperMag3 
[nspid]Source 
WSA NonSurvey 
Default point/extended source Br aperture corrected mag (2.0 arcsec aperture diameter) If in doubt use this flux estimator 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
brAperMag3 
[nspid]SynopticSource 
WSA NonSurvey 
Default point/extended source Br aperture corrected mag (2.0 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
brAperMag3Err 
[nspid]Source 
WSA NonSurvey 
Error in default point source Br mag (2.0 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
ERROR 
brAperMag3Err 
[nspid]Source, [nspid]SynopticSource 
WSA NonSurvey 
Error in default point/extended source Br mag (2.0 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
ERROR 
brAperMag4 
[nspid]Source 
WSA NonSurvey 
Point source Br aperture corrected mag (2.8 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
brAperMag4 
[nspid]Source, [nspid]SynopticSource 
WSA NonSurvey 
Extended source Br aperture corrected mag (2.8 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
brAperMag4Err 
[nspid]Source 
WSA NonSurvey 
Error in point source Br mag (2.8 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
ERROR 
brAperMag4Err 
[nspid]Source, [nspid]SynopticSource 
WSA NonSurvey 
Error in extended source Br mag (2.8 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
ERROR 
brAperMag5 
[nspid]SynopticSource 
WSA NonSurvey 
Extended source Br aperture corrected mag (4.0 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
brAperMag5Err 
[nspid]SynopticSource 
WSA NonSurvey 
Error in extended source Br mag (4.0 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
ERROR 
brAperMag6 
[nspid]Source 
WSA NonSurvey 
Extended source Br aperture corrected mag (5.7 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
brAperMag6 
[nspid]Source 
WSA NonSurvey 
Point source Br aperture corrected mag (5.7 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
brAperMag6Err 
[nspid]Source 
WSA NonSurvey 
Error in extended source Br mag (5.7 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
ERROR 
brAperMag6Err 
[nspid]Source 
WSA NonSurvey 
Error in point source Br mag (5.7 arcsec aperture diameter) 
real 
4 
mag 
0.9999995e9 
ERROR 
braStratAst 
[nspid]VarFrameSetInfo 
WSA NonSurvey 
Strateva parameter, a, in fit to astrometric rms vs magnitude in Br 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. 
braStratPht 
[nspid]VarFrameSetInfo 
WSA NonSurvey 
Strateva parameter, a, in fit to photometric rms vs magnitude in Br 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. 
brbestAper 
[nspid]Variability 
WSA NonSurvey 
Best aperture (16) for photometric statistics in the Br 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) 
brbStratAst 
[nspid]VarFrameSetInfo 
WSA NonSurvey 
Strateva parameter, b, in fit to astrometric rms vs magnitude in Br 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. 
brbStratPht 
[nspid]VarFrameSetInfo 
WSA NonSurvey 
Strateva parameter, b, in fit to photometric rms vs magnitude in Br 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. 
brchiSqAst 
[nspid]VarFrameSetInfo 
WSA NonSurvey 
Goodness of fit of Strateva function to astrometric data in Br 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. 
brchiSqpd 
[nspid]Variability 
WSA NonSurvey 
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. 
brchiSqPht 
[nspid]VarFrameSetInfo 
WSA NonSurvey 
Goodness of fit of Strateva function to photometric data in Br 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. 
brClass 
[nspid]Source, [nspid]SynopticSource 
WSA NonSurvey 
discrete image classification flag in Br 
smallint 
2 

9999 
CLASS_MISC 
brClassStat 
[nspid]Source, [nspid]SynopticSource 
WSA NonSurvey 
N(0,1) stellarnessofprofile statistic in Br 
real 
4 

0.9999995e9 
STAT_PROP 
brcStratAst 
[nspid]VarFrameSetInfo 
WSA NonSurvey 
Strateva parameter, c, in fit to astrometric rms vs magnitude in Br 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. 
brcStratPht 
[nspid]VarFrameSetInfo 
WSA NonSurvey 
Strateva parameter, c, in fit to photometric rms vs magnitude in Br 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. 
brDeblend 
[nspid]Source 
WSA NonSurvey 
placeholder flag indicating parent/child relation in Br 
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. 
brDeblend 
[nspid]SynopticSource 
WSA NonSurvey 
placeholder flag indicating parent/child relation in Br 
int 
4 

99999999 
CODE_MISC 
brEll 
[nspid]Source, [nspid]SynopticSource 
WSA NonSurvey 
1b/a, where a/b=semimajor/minor axes in Br 
real 
4 

0.9999995e9 
PHYS_ELLIPTICITY 
breNum 
[nspid]MergeLog, [nspid]SynopticMergeLog 
WSA NonSurvey 
the extension number of this Br frame 
tinyint 
1 


NUMBER 
brErrBits 
[nspid]Source, [nspid]SynopticSource 
WSA NonSurvey 
processing warning/error bitwise flags in Br 
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. 
brEta 
[nspid]Source, [nspid]SynopticSource 
WSA NonSurvey 
Offset of Br 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. 
brexpML 
[nspid]VarFrameSetInfo 
WSA NonSurvey 
Expected magnitude limit of frameSet in this in Br 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. 
brExpRms 
[nspid]Variability 
WSA NonSurvey 
Rms calculated from polynomial fit to modal RMS as a function of magnitude in Br 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. 
brGausig 
[nspid]Source, [nspid]SynopticSource 
WSA NonSurvey 
RMS of axes of ellipse fit in Br 
real 
4 
pixels 
0.9999995e9 
MORPH_PARAM 
brHallMag 
[nspid]Source 
WSA NonSurvey 
Total point source Br mag 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
brHallMagErr 
[nspid]Source 
WSA NonSurvey 
Error in total point source Br mag 
real 
4 
mag 
0.9999995e9 
ERROR 
brIntRms 
[nspid]Variability 
WSA NonSurvey 
Intrinsic rms in Brband 
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. 
brisDefAst 
[nspid]VarFrameSetInfo 
WSA NonSurvey 
Use a default model for the astrometric noise in Br band. 
tinyint 
1 

0 

brisDefPht 
[nspid]VarFrameSetInfo 
WSA NonSurvey 
Use a default model for the photometric noise in Br band. 
tinyint 
1 

0 

brMagMAD 
[nspid]Variability 
WSA NonSurvey 
Median Absolute Deviation of Br 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. 
brMagRms 
[nspid]Variability 
WSA NonSurvey 
rms of Br 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. 
brmaxCadence 
[nspid]Variability 
WSA NonSurvey 
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. 
brMaxMag 
[nspid]Variability 
WSA NonSurvey 
Maximum magnitude in Br 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. 
brmeanMag 
[nspid]Variability 
WSA NonSurvey 
Mean Br 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. 
brmedCadence 
[nspid]Variability 
WSA NonSurvey 
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. 
brmedianMag 
[nspid]Variability 
WSA NonSurvey 
Median Br 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. 
brmfID 
[nspid]MergeLog, [nspid]SynopticMergeLog 
WSA NonSurvey 
the UID of the relevant Br multiframe 
bigint 
8 


ID_FRAME 
brminCadence 
[nspid]Variability 
WSA NonSurvey 
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. 
brMinMag 
[nspid]Variability 
WSA NonSurvey 
Minimum magnitude in Br 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. 
brmkExt 
[nspid]Source 
WSA NonSurvey 
Extended source colour BrK (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. 
brmkExtErr 
[nspid]Source 
WSA NonSurvey 
Error on extended source colour BrK 
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. 
brmkPnt 
[nspid]Source, [nspid]SynopticSource 
WSA NonSurvey 
Point source colour BrK (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. 
brmkPntErr 
[nspid]Source, [nspid]SynopticSource 
WSA NonSurvey 
Error on point source colour BrK 
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. 
brndof 
[nspid]Variability 
WSA NonSurvey 
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. 
brnDofAst 
[nspid]VarFrameSetInfo 
WSA NonSurvey 
Number of degrees of freedom of astrometric fit in Br 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. 
brnDofPht 
[nspid]VarFrameSetInfo 
WSA NonSurvey 
Number of degrees of freedom of photometric fit in Br 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. 
brnFlaggedObs 
[nspid]Variability 
WSA NonSurvey 
Number of detections in Br 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. 
brnGoodObs 
[nspid]Variability 
WSA NonSurvey 
Number of good detections in Br 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. 
brNgt3sig 
[nspid]Variability 
WSA NonSurvey 
Number of good detections in Brband 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. 
brnMissingObs 
[nspid]Variability 
WSA NonSurvey 
Number of Br 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. 
brPA 
[nspid]Source, [nspid]SynopticSource 
WSA NonSurvey 
ellipse fit celestial orientation in Br 
real 
4 
Degrees 
0.9999995e9 
POS_POSANG 
brPetroMag 
[nspid]Source 
WSA NonSurvey 
Extended source Br mag (Petrosian) 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
brPetroMagErr 
[nspid]Source 
WSA NonSurvey 
Error in extended source Br mag (Petrosian) 
real 
4 
mag 
0.9999995e9 
ERROR 
brppErrBits 
[nspid]Source, [nspid]SynopticSource 
WSA NonSurvey 
additional WFAU postprocessing error bits in Br 
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. 
brprobVar 
[nspid]Variability 
WSA NonSurvey 
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. 
brPsfMag 
[nspid]Source 
WSA NonSurvey 
Point source profilefitted Br mag 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
brPsfMagErr 
[nspid]Source 
WSA NonSurvey 
Error in point source profilefitted Br mag 
real 
4 
mag 
0.9999995e9 
ERROR 
brSeqNum 
[nspid]Source, [nspid]SynopticSource 
WSA NonSurvey 
the running number of the Br detection 
int 
4 

99999999 
ID_NUMBER 
brSerMag2D 
[nspid]Source 
WSA NonSurvey 
Extended source Br mag (profilefitted) 
real 
4 
mag 
0.9999995e9 
PHOT_MAG 
brSerMag2DErr 
[nspid]Source 
WSA NonSurvey 
Error in extended source Br mag (profilefitted) 
real 
4 
mag 
0.9999995e9 
ERROR 
brskewness 
[nspid]Variability 
WSA NonSurvey 
Skewness in Br 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. 
brtotalPeriod 
[nspid]Variability 
WSA NonSurvey 
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. 
brVarClass 
[nspid]Variability 
WSA NonSurvey 
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. 
brXi 
[nspid]Source, [nspid]SynopticSource 
WSA NonSurvey 
Offset of Br 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. 