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** Announcement - Workshop: Science from UKIDSS II, 15-17 Dec 2008, London UK **
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Glossary of WSA attributes

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

Z

NameSchema TableDatabaseDescriptionTypeLengthUnitDefault ValueUnified Content Descriptor
z11 Multiframe WSA Spherical: Z11 {image primary HDU keyword: Z11} real 4   -0.9999995e9  
z7 Multiframe WSA Coma: Z7 {image primary HDU keyword: Z7} real 4   -0.9999995e9  
z8 Multiframe WSA Coma: Z8 {image primary HDU keyword: Z8} real 4   -0.9999995e9  
zAperMag3 gcsSource WSA Default point/extended source Z aperture corrected mag (2.0 arcsec aperture diameter)
If in doubt use this flux estimator
real 4 mag -0.9999995e9 PHOT_MAG
zAperMag3Err gcsSource WSA Error in default point/extended source Z mag (2.0 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR
zAperMag4 gcsSource WSA Extended source Z aperture corrected mag (2.8 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG
zAperMag4Err gcsSource WSA Error in extended source Z mag (2.8 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR
zAperMag6 gcsSource WSA Extended source Z aperture corrected mag (5.7 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG
zAperMag6Err gcsSource WSA Error in extended source Z mag (5.7 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR
zClass gcsSource, gcsSourceRemeasurement WSA discrete image classification flag in Z smallint 2   -9999 CLASS_MISC
zClassStat gcsSource, gcsSourceRemeasurement WSA N(0,1) stellarness-of-profile statistic in Z real 4   -0.9999995e9 STAT_PROP
zd twomass_scn 2MASS Scan's distance from the zenith at beginning of scan. real 4 degrees   POS_ZD_RES
zDeblend gcsSource, gcsSourceRemeasurement WSA flag indicating parent/child relation in Z int 4   -99999999 CODE_MISC
zEll gcsSource, gcsSourceRemeasurement WSA 1-b/a, where a/b=semi-major/minor axes in Z real 4   -0.9999995e9 PHYS_ELLIPTICITY
zeNum gcsMergeLog WSA the extension number of this Z frame tinyint 1     NUMBER
zErrBits gcsSource, gcsSourceRemeasurement WSA processing warning/error bitwise flags in Z int 4   -99999999 CODE_MISC
zEta gcsSource WSA Offset of Z detection from master position (+north/-south) real 4 arcsec -0.9999995e9 POS_EQ_DEC_OFF
When associating individual passband detections into merged sources, a generous (in terms of the positional uncertainties) pairing radius of typically 5 arcseconds is used, 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, 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.
zGausig gcsSource, gcsSourceRemeasurement WSA RMS of axes of ellipse fit in Z real 4 pixels -0.9999995e9 MORPH_PARAM
zHallMag gcsSource WSA Total point source Z mag real 4 mag -0.9999995e9 PHOT_MAG
zHallMagErr gcsSource WSA Error in total point source Z mag real 4 mag -0.9999995e9 ERROR
zMag CurrentStdStarInfo, PreviousStdStarInfo WSA Z band total magnitude of star (from external sources if primary) real 4 mag   PHOT_INT-MAG
zMag gcsSourceRemeasurement WSA Z mag (as appropriate for this merged source) real 4 mag -0.9999995e9 PHOT_MAG
zMagErr CurrentStdStarInfo, PreviousStdStarInfo WSA Z band magnitude error of star real 4 mag   ERROR
zMagErr gcsSourceRemeasurement WSA Error in Z mag real 4 mag -0.9999995e9 ERROR
zmfID gcsMergeLog WSA the UID of the relevant Z multiframe bigint 8     ID_FRAME
zmy gcsSourceRemeasurement WSA Default colour Z-Y (using appropriate mags) real 4 mag   PHOT_COLOR
zmyErr gcsSourceRemeasurement WSA Error on colour Z-Y real 4 mag   ERROR
zmyExt gcsSource WSA Extended source colour Z-Y (using aperMag3) real 4 mag -0.9999995e9 PHOT_COLOR
Default colours from pairs of adjacent passbands within a given set (e.g. Y-J, J-H and H-K for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the point-source colours and extended source colours are computed from the aperture corrected AperMag3 fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands) and generally good signal-to-noise. At some point in the future, this may be changed such that point-source colours will be computed from the PSF-fitted measures and extended source colours computed from the 2-d Sersic model profile fits.
zmyExtErr gcsSource WSA Error on extended source colour Z-Y real 4 mag -0.9999995e9 ERROR
Default colours from pairs of adjacent passbands within a given set (e.g. Y-J, J-H and H-K for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the point-source colours and extended source colours are computed from the aperture corrected AperMag3 fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands) and generally good signal-to-noise. At some point in the future, this may be changed such that point-source colours will be computed from the PSF-fitted measures and extended source colours computed from the 2-d Sersic model profile fits.
zmyPnt gcsSource WSA Point source colour Z-Y (using aperMag3) real 4 mag -0.9999995e9 PHOT_COLOR
Default colours from pairs of adjacent passbands within a given set (e.g. Y-J, J-H and H-K for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the point-source colours and extended source colours are computed from the aperture corrected AperMag3 fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands) and generally good signal-to-noise. At some point in the future, this may be changed such that point-source colours will be computed from the PSF-fitted measures and extended source colours computed from the 2-d Sersic model profile fits.
zmyPntErr gcsSource WSA Error on point source colour Z-Y real 4 mag -0.9999995e9 ERROR
Default colours from pairs of adjacent passbands within a given set (e.g. Y-J, J-H and H-K for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the point-source colours and extended source colours are computed from the aperture corrected AperMag3 fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands) and generally good signal-to-noise. At some point in the future, this may be changed such that point-source colours will be computed from the PSF-fitted measures and extended source colours computed from the 2-d Sersic model profile fits.
zObjID gcsSource WSA the UID of the Z detection bigint 8   -99999999 ID_NUMBER
zObjID gcsSourceRemeasurement WSA the UID of the Z remeasurement bigint 8   -99999999 ID_NUMBER
zone ExternalSurveyTable, ProgrammeTable WSA default (0) or special (n) zone smallint 2     ID_REGION
zp0 CurrentZP WSA the zeroth-order zeropoint coefficient float 8   0.0 PHOT_ZP
zp0 PreviousZP WSA the zeroth-order zeropoint coefficient float 8     PHOT_ZP
zp1 CurrentZP WSA the first-order zeropoint coefficient wrt time during night float 8   0.0 PHOT_ZP
zp1 PreviousZP WSA the first-order zeropoint coefficient wrt time during night float 8     PHOT_ZP
zp2 CurrentZP WSA the second-order zeropoint coefficient wrt time during night float 8   0.0 PHOT_ZP
zp2 PreviousZP WSA the second-order zeropoint coefficient wrt time during night float 8     PHOT_ZP
zp3 CurrentZP WSA the first-order zeropoint coefficient wrt time across nights (long-term decay of detector) float 8   0.0 PHOT_ZP
zp3 PreviousZP WSA the first-order zeropoint coefficient wrt time across nights (long-term decay of detector) float 8     PHOT_ZP
zp4 CurrentZP WSA the second-order zeropoint coefficient wrt time across nights (long-term decay of detector) float 8   0.0 PHOT_ZP
zp4 PreviousZP WSA the second-order zeropoint coefficient wrt time across nights (long-term decay of detector) float 8     PHOT_ZP
zPA gcsSource, gcsSourceRemeasurement WSA ellipse fit celestial orientation in Z real 4 Degrees -0.9999995e9 POS_POS-ANG
zPetroMag gcsSource WSA Extended source Z mag (Petrosian) real 4 mag -0.9999995e9 PHOT_MAG
zPetroMagErr gcsSource WSA Error in extended source Z mag (Petrosian) real 4 mag -0.9999995e9 ERROR
zppErrBits gcsSource, gcsSourceRemeasurement WSA additional WFAU post-processing error bits in Z int 4   0 CODE_MISC
zPsfMag gcsSource WSA Point source profile-fitted Z mag real 4 mag -0.9999995e9 PHOT_MAG
zPsfMagErr gcsSource WSA Error in point source profile-fitted Z mag real 4 mag -0.9999995e9 ERROR
zSeqNum gcsSource WSA the running number of the Z detection int 4   -99999999 ID_NUMBER
zSeqNum gcsSourceRemeasurement WSA the running number of the Z remeasurement int 4   -99999999 ID_NUMBER
zSerMag2D gcsSource WSA Extended source Z mag (profile-fitted) real 4 mag -0.9999995e9 PHOT_MAG
zSerMag2DErr gcsSource WSA Error in extended source Z mag (profile-fitted) real 4 mag -0.9999995e9 ERROR
zXi gcsSource WSA Offset of Z detection from master position (+east/-west) real 4 arcsec -0.9999995e9 POS_EQ_RA_OFF
When associating individual passband detections into merged sources, a generous (in terms of the positional uncertainties) pairing radius of typically 5 arcseconds is used, 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, 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.



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