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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 UKIDSSR2 database(s) held in the WSA. If you would like to have more information about the schema tables please use the UKIDSSR2 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

K

NameSchema TableDatabaseDescriptionTypeLengthUnitDefault ValueUnified Content Descriptor
k_1AperMag3 gcsSource, gpsSource WSA Extended source K (1st epoch) mag (2.0 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG
k_1AperMag3Err gcsSource, gpsSource WSA Error in extended source K (1st epoch) mag (2.0 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR
k_1AperMag4 gcsSource, gpsSource WSA Extended source K (1st epoch) mag (2.8 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG
k_1AperMag4Err gcsSource, gpsSource WSA Error in extended source K (1st epoch) mag (2.8 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR
k_1AperMag6 gcsSource, gpsSource WSA Extended source K (1st epoch) mag (5.7 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG
k_1AperMag6Err gcsSource, gpsSource WSA Error in extended source K (1st epoch) mag (5.7 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR
k_1Class gcsSource, gcsSourceRemeasurement, gpsSource, gpsSourceRemeasurement WSA discrete image classification flag in 1st epoch K smallint 2   -9999 CLASS_MISC
k_1ClassStat gcsSource, gcsSourceRemeasurement, gpsSource, gpsSourceRemeasurement WSA N(0,1) stellarness-of-profile statistic in 1st epoch K real 4   -0.9999995e9 STAT_PROP
k_1Deblend gcsSource, gcsSourceRemeasurement, gpsSource, gpsSourceRemeasurement WSA flag indicating parent/child relation in 1st epoch K int 4   -99999999 CODE_MISC
k_1Ell gcsSource, gcsSourceRemeasurement, gpsSource, gpsSourceRemeasurement WSA 1-b/a, where a/b=semi-major/minor axes in 1st epoch K real 4   -0.9999995e9 PHYS_ELLIPTICITY
k_1eNum gcsMergeLog, gpsMergeLog WSA the extension number of this K frame (ep1) tinyint 1     NUMBER
k_1ErrBits gcsSource, gcsSourceRemeasurement, gpsSource, gpsSourceRemeasurement WSA processing warning/error bitwise flags in 1st epoch K int 4   -99999999 CODE_MISC
k_1Eta gcsSource, gpsSource WSA Offset of K1 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.
k_1Gausig gcsSource, gcsSourceRemeasurement, gpsSource, gpsSourceRemeasurement WSA RMS of axes of ellipse fit in 1st epoch K real 4 pixels -0.9999995e9 MORPH_PARAM
k_1HallMag gcsSource, gpsSource WSA Point source K (1st epoch) mag real 4 mag -0.9999995e9 PHOT_MAG
k_1HallMagErr gcsSource, gpsSource WSA Error in point source K (1st epoch) mag real 4 mag -0.9999995e9 ERROR
k_1Mag gcsSourceRemeasurement, gpsSourceRemeasurement WSA 1st epoch K mag (as appropriate for this merged source) real 4 mag -0.9999995e9 PHOT_MAG
k_1MagErr gcsSourceRemeasurement, gpsSourceRemeasurement WSA Error in 1st epoch K mag real 4 mag -0.9999995e9 ERROR
k_1mfID gcsMergeLog, gpsMergeLog WSA the UID of the relevant K multiframe (ep1) bigint 8     ID_FRAME
k_1ObjID gcsSource WSA the UID of the 1st K detection bigint 8   -99999999 ID_NUMBER
k_1ObjID gcsSourceRemeasurement, gpsSourceRemeasurement WSA the UID of the 1st K remeasurement bigint 8   -99999999 ID_NUMBER
k_1ObjID gpsSource WSA the UID of the K1 detection bigint 8   -99999999 ID_NUMBER
k_1PA gcsSource, gcsSourceRemeasurement, gpsSource, gpsSourceRemeasurement WSA ellipse fit celestial orientation in 1st epoch K real 4 Degrees -0.9999995e9 POS_POS-ANG
k_1PetroMag gcsSource, gpsSource WSA Extended source K (1st epoch) mag (Petrosian) real 4 mag -0.9999995e9 PHOT_MAG
k_1PetroMagErr gcsSource, gpsSource WSA Error in extended source K (1st epoch) mag (Petrosian) real 4 mag -0.9999995e9 ERROR
k_1ppErrBits gcsSource, gcsSourceRemeasurement, gpsSource, gpsSourceRemeasurement WSA additional WFAU post-processing error bits in 1st epoch K int 4   -99999999 CODE_MISC
k_1PsfMag gcsSource, gpsSource WSA Point source profile-fitted K (1st epoch) mag real 4 mag -0.9999995e9 PHOT_MAG
k_1PsfMagErr gcsSource, gpsSource WSA Error in point source profile-fitted K (1st epoch) mag real 4 mag -0.9999995e9 ERROR
k_1SeqNum gcsSource WSA the running number of the 1st K detection int 4   -99999999 ID_NUMBER
k_1SeqNum gcsSourceRemeasurement, gpsSourceRemeasurement WSA the running number of the 1st K remeasurement int 4   -99999999 ID_NUMBER
k_1SeqNum gpsSource WSA the running number of the K1 detection int 4   -99999999 ID_NUMBER
k_1SerMag2D gcsSource, gpsSource WSA Extended source K (1st epoch) mag (profile-fitted) real 4 mag -0.9999995e9 PHOT_MAG
k_1SerMag2DErr gcsSource, gpsSource WSA Error in extended source K (1st epoch) mag (profile-fitted) real 4 mag -0.9999995e9 ERROR
k_1Xi gcsSource, gpsSource WSA Offset of K1 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.
k_2AperMag3 gcsSource, gpsSource WSA Extended source K (2nd epoch) mag (2.0 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG
k_2AperMag3Err gcsSource, gpsSource WSA Error in extended source K (2nd epoch) mag (2.0 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR
k_2AperMag4 gcsSource, gpsSource WSA Extended source K (2nd epoch) mag (2.8 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG
k_2AperMag4Err gcsSource, gpsSource WSA Error in extended source K (2nd epoch) mag (2.8 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR
k_2AperMag6 gcsSource, gpsSource WSA Extended source K (2nd epoch) mag (5.7 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG
k_2AperMag6Err gcsSource, gpsSource WSA Error in extended source K (2nd epoch) mag (5.7 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR
k_2Class gcsSource, gcsSourceRemeasurement, gpsSource, gpsSourceRemeasurement WSA discrete image classification flag in 2nd epoch K smallint 2   -9999 CLASS_MISC
k_2ClassStat gcsSource, gcsSourceRemeasurement, gpsSource, gpsSourceRemeasurement WSA N(0,1) stellarness-of-profile statistic in 2nd epoch K real 4   -0.9999995e9 STAT_PROP
k_2Deblend gcsSource, gcsSourceRemeasurement, gpsSource, gpsSourceRemeasurement WSA flag indicating parent/child relation in 2nd epoch K int 4   -99999999 CODE_MISC
k_2Ell gcsSource, gcsSourceRemeasurement, gpsSource, gpsSourceRemeasurement WSA 1-b/a, where a/b=semi-major/minor axes in 2nd epoch K real 4   -0.9999995e9 PHYS_ELLIPTICITY
k_2eNum gcsMergeLog, gpsMergeLog WSA the extension number of this K frame (ep2) tinyint 1     NUMBER
k_2ErrBits gcsSource, gcsSourceRemeasurement, gpsSource, gpsSourceRemeasurement WSA processing warning/error bitwise flags in 2nd epoch K int 4   -99999999 CODE_MISC
k_2Eta gcsSource, gpsSource WSA Offset of K2 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.
k_2Gausig gcsSource, gcsSourceRemeasurement, gpsSource, gpsSourceRemeasurement WSA RMS of axes of ellipse fit in 2nd epoch K real 4 pixels -0.9999995e9 MORPH_PARAM
k_2HallMag gcsSource, gpsSource WSA Point source K (2nd epoch) mag real 4 mag -0.9999995e9 PHOT_MAG
k_2HallMagErr gcsSource, gpsSource WSA Error in point source K (2nd epoch) mag real 4 mag -0.9999995e9 ERROR
k_2Mag gcsSourceRemeasurement, gpsSourceRemeasurement WSA 2nd epoch K mag (as appropriate for this merged source) real 4 mag -0.9999995e9 PHOT_MAG
k_2MagErr gcsSourceRemeasurement, gpsSourceRemeasurement WSA Error in 2nd epoch K mag real 4 mag -0.9999995e9 ERROR
k_2mfID gcsMergeLog, gpsMergeLog WSA the UID of the relevant K multiframe (ep2) bigint 8     ID_FRAME
k_2mrat twomass_scn 2MASS Ks-band average 2nd image moment ratio. real 4     FIT_PARAM_VALUE
k_2ObjID gcsSource WSA the UID of the 2nd K detection bigint 8   -99999999 ID_NUMBER
k_2ObjID gcsSourceRemeasurement, gpsSourceRemeasurement WSA the UID of the 2nd K remeasurement bigint 8   -99999999 ID_NUMBER
k_2ObjID gpsSource WSA the UID of the K2 detection bigint 8   -99999999 ID_NUMBER
k_2PA gcsSource, gcsSourceRemeasurement, gpsSource, gpsSourceRemeasurement WSA ellipse fit celestial orientation in 2nd epoch K real 4 Degrees -0.9999995e9 POS_POS-ANG
k_2PetroMag gcsSource, gpsSource WSA Extended source K (2nd epoch) mag (Petrosian) real 4 mag -0.9999995e9 PHOT_MAG
k_2PetroMagErr gcsSource, gpsSource WSA Error in extended source K (2nd epoch) mag (Petrosian) real 4 mag -0.9999995e9 ERROR
k_2ppErrBits gcsSource, gcsSourceRemeasurement, gpsSource, gpsSourceRemeasurement WSA additional WFAU post-processing error bits in 2nd epoch K int 4   -99999999 CODE_MISC
k_2PsfMag gcsSource, gpsSource WSA Point source profile-fitted K (2nd epoch) mag real 4 mag -0.9999995e9 PHOT_MAG
k_2PsfMagErr gcsSource, gpsSource WSA Error in point source profile-fitted K (2nd epoch) mag real 4 mag -0.9999995e9 ERROR
k_2SeqNum gcsSource WSA the running number of the 2nd K detection int 4   -99999999 ID_NUMBER
k_2SeqNum gcsSourceRemeasurement, gpsSourceRemeasurement WSA the running number of the 2nd K remeasurement int 4   -99999999 ID_NUMBER
k_2SeqNum gpsSource WSA the running number of the K2 detection int 4   -99999999 ID_NUMBER
k_2SerMag2D gcsSource, gpsSource WSA Extended source K (2nd epoch) mag (profile-fitted) real 4 mag -0.9999995e9 PHOT_MAG
k_2SerMag2DErr gcsSource, gpsSource WSA Error in extended source K (2nd epoch) mag (profile-fitted) real 4 mag -0.9999995e9 ERROR
k_2Xi gcsSource, gpsSource WSA Offset of K2 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.
k_3AperMag3 gpsSource WSA Extended source K (3rd epoch) mag (2.0 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG
k_3AperMag3Err gpsSource WSA Error in extended source K (3rd epoch) mag (2.0 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR
k_3AperMag4 gpsSource WSA Extended source K (3rd epoch) mag (2.8 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG
k_3AperMag4Err gpsSource WSA Error in extended source K (3rd epoch) mag (2.8 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR
k_3AperMag6 gpsSource WSA Extended source K (3rd epoch) mag (5.7 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG
k_3AperMag6Err gpsSource WSA Error in extended source K (3rd epoch) mag (5.7 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR
k_3Class gpsSource, gpsSourceRemeasurement WSA discrete image classification flag in 3rd epoch K smallint 2   -9999 CLASS_MISC
k_3ClassStat gpsSource, gpsSourceRemeasurement WSA N(0,1) stellarness-of-profile statistic in 3rd epoch K real 4   -0.9999995e9 STAT_PROP
k_3Deblend gpsSource, gpsSourceRemeasurement WSA flag indicating parent/child relation in 3rd epoch K int 4   -99999999 CODE_MISC
k_3Ell gpsSource, gpsSourceRemeasurement WSA 1-b/a, where a/b=semi-major/minor axes in 3rd epoch K real 4   -0.9999995e9 PHYS_ELLIPTICITY
k_3eNum gpsMergeLog WSA the extension number of this K frame (ep3) tinyint 1     NUMBER
k_3ErrBits gpsSource, gpsSourceRemeasurement WSA processing warning/error bitwise flags in 3rd epoch K int 4   -99999999 CODE_MISC
k_3Eta gpsSource WSA Offset of K3 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.
k_3Gausig gpsSource, gpsSourceRemeasurement WSA RMS of axes of ellipse fit in 3rd epoch K real 4 pixels -0.9999995e9 MORPH_PARAM
k_3HallMag gpsSource WSA Point source K (3rd epoch) mag real 4 mag -0.9999995e9 PHOT_MAG
k_3HallMagErr gpsSource WSA Error in point source K (3rd epoch) mag real 4 mag -0.9999995e9 ERROR
k_3Mag gpsSourceRemeasurement WSA 3rd epoch K mag (as appropriate for this merged source) real 4 mag -0.9999995e9 PHOT_MAG
k_3MagErr gpsSourceRemeasurement WSA Error in 3rd epoch K mag real 4 mag -0.9999995e9 ERROR
k_3mfID gpsMergeLog WSA the UID of the relevant K multiframe (ep3) bigint 8     ID_FRAME
k_3ObjID gpsSource WSA the UID of the K3 detection bigint 8   -99999999 ID_NUMBER
k_3ObjID gpsSourceRemeasurement WSA the UID of the 3rd K remeasurement bigint 8   -99999999 ID_NUMBER
k_3PA gpsSource, gpsSourceRemeasurement WSA ellipse fit celestial orientation in 3rd epoch K real 4 Degrees -0.9999995e9 POS_POS-ANG
k_3PetroMag gpsSource WSA Extended source K (3rd epoch) mag (Petrosian) real 4 mag -0.9999995e9 PHOT_MAG
k_3PetroMagErr gpsSource WSA Error in extended source K (3rd epoch) mag (Petrosian) real 4 mag -0.9999995e9 ERROR
k_3ppErrBits gpsSource, gpsSourceRemeasurement WSA additional WFAU post-processing error bits in 3rd epoch K int 4   -99999999 CODE_MISC
k_3PsfMag gpsSource WSA Point source profile-fitted K (3rd epoch) mag real 4 mag -0.9999995e9 PHOT_MAG
k_3PsfMagErr gpsSource WSA Error in point source profile-fitted K (3rd epoch) mag real 4 mag -0.9999995e9 ERROR
k_3SeqNum gpsSource WSA the running number of the K3 detection int 4   -99999999 ID_NUMBER
k_3SeqNum gpsSourceRemeasurement WSA the running number of the 3rd K remeasurement int 4   -99999999 ID_NUMBER
k_3SerMag2D gpsSource WSA Extended source K (3rd epoch) mag (profile-fitted) real 4 mag -0.9999995e9 PHOT_MAG
k_3SerMag2DErr gpsSource WSA Error in extended source K (3rd epoch) mag (profile-fitted) real 4 mag -0.9999995e9 ERROR
k_3Xi gpsSource WSA Offset of K3 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.
k_5sig_ba twomass_xsc 2MASS K minor/major axis ratio fit to the 5-sigma isophote. real 4     PHYS_AXIS-RATIO
k_5sig_phi twomass_xsc 2MASS K angle to 5-sigma major axis (E of N). smallint 2 degrees   ERROR
k_5surf twomass_xsc 2MASS K central surface brightness (r<=5). real 4 mag   PHOT_SB_GENERAL
k_ba twomass_xsc 2MASS K minor/major axis ratio fit to the 3-sigma isophote. real 4     PHYS_AXIS-RATIO
k_back twomass_xsc 2MASS K coadd median background. real 4     CODE_MISC
k_bisym_chi twomass_xsc 2MASS K bi-symmetric cross-correlation chi. real 4     FIT_PARAM_VALUE
k_bisym_rat twomass_xsc 2MASS K bi-symmetric flux ratio. real 4     PHOT_FLUX_RATIO
k_bndg_amp twomass_xsc 2MASS K banding maximum FT amplitude on this side of coadd. real 4 DN   FIT_PARAM_VALUE
k_bndg_per twomass_xsc 2MASS K banding Fourier Transf. period on this side of coadd. int 4 arcsec   FIT_PARAM_VALUE
k_chif_ellf twomass_xsc 2MASS K % chi-fraction for elliptical fit to 3-sig isophote. real 4     FIT_PARAM_VALUE
k_cmsig twomass_psc 2MASS Corrected photometric uncertainty for the default Ks-band magnitude. real 4 mag   SPECT_FLUX_VALUE
k_con_indx twomass_xsc 2MASS K concentration index r_75%/r_25%. real 4     PHYS_CONCENT_INDEX
k_d_area twomass_xsc 2MASS K 5-sigma to 3-sigma differential area. smallint 2     FIT_RESIDUAL
k_flg_10 twomass_xsc 2MASS K confusion flag for 10 arcsec circular ap. mag. smallint 2     CODE_MISC
k_flg_15 twomass_xsc 2MASS K confusion flag for 15 arcsec circular ap. mag. smallint 2     CODE_MISC
k_flg_20 twomass_xsc 2MASS K confusion flag for 20 arcsec circular ap. mag. smallint 2     CODE_MISC
k_flg_25 twomass_xsc 2MASS K confusion flag for 25 arcsec circular ap. mag. smallint 2     CODE_MISC
k_flg_30 twomass_xsc 2MASS K confusion flag for 30 arcsec circular ap. mag. smallint 2     CODE_MISC
k_flg_40 twomass_xsc 2MASS K confusion flag for 40 arcsec circular ap. mag. smallint 2     CODE_MISC
k_flg_5 twomass_xsc 2MASS K confusion flag for 5 arcsec circular ap. mag. smallint 2     CODE_MISC
k_flg_50 twomass_xsc 2MASS K confusion flag for 50 arcsec circular ap. mag. smallint 2     CODE_MISC
k_flg_60 twomass_xsc 2MASS K confusion flag for 60 arcsec circular ap. mag. smallint 2     CODE_MISC
k_flg_7 twomass_xsc 2MASS K confusion flag for 7 arcsec circular ap. mag. smallint 2     CODE_MISC
k_flg_70 twomass_xsc 2MASS K confusion flag for 70 arcsec circular ap. mag. smallint 2     CODE_MISC
k_flg_c twomass_xsc 2MASS K confusion flag for Kron circular mag. smallint 2     CODE_MISC
k_flg_e twomass_xsc 2MASS K confusion flag for Kron elliptical mag. smallint 2     CODE_MISC
k_flg_fc twomass_xsc 2MASS K confusion flag for fiducial Kron circ. mag. smallint 2     CODE_MISC
k_flg_fe twomass_xsc 2MASS K confusion flag for fiducial Kron ell. mag. smallint 2     CODE_MISC
k_flg_i20c twomass_xsc 2MASS K confusion flag for 20mag/sq." iso. circ. mag. smallint 2     CODE_MISC
k_flg_i20e twomass_xsc 2MASS K confusion flag for 20mag/sq." iso. ell. mag. smallint 2     CODE_MISC
k_flg_i21c twomass_xsc 2MASS K confusion flag for 21mag/sq." iso. circ. mag. smallint 2     CODE_MISC
k_flg_i21e twomass_xsc 2MASS K confusion flag for 21mag/sq." iso. ell. mag. smallint 2     CODE_MISC
k_flg_j21fc twomass_xsc 2MASS K confusion flag for 21mag/sq." iso. fid. circ. mag. smallint 2     CODE_MISC
k_flg_j21fe twomass_xsc 2MASS K confusion flag for 21mag/sq." iso. fid. ell. mag. smallint 2     CODE_MISC
k_flg_k20fc twomass_xsc 2MASS K confusion flag for 20mag/sq." iso. fid. circ. mag. smallint 2     CODE_MISC
k_flg_k20fe twomass_xsc 2MASS K confusion flag for 20mag/sq." iso. fid. ell. mag. smallint 2     CODE_MISC
k_m twomass_psc 2MASS Default Ks-band magnitude real 4 mag   SPECT_FLUX_VALUE
k_m_10 twomass_xsc 2MASS K 10 arcsec radius circular aperture magnitude. real 4 mag   SPECT_FLUX_VALUE
k_m_15 twomass_xsc 2MASS K 15 arcsec radius circular aperture magnitude. real 4 mag   SPECT_FLUX_VALUE
k_m_20 twomass_xsc 2MASS K 20 arcsec radius circular aperture magnitude. real 4 mag   SPECT_FLUX_VALUE
k_m_25 twomass_xsc 2MASS K 25 arcsec radius circular aperture magnitude. real 4 mag   SPECT_FLUX_VALUE
k_m_30 twomass_xsc 2MASS K 30 arcsec radius circular aperture magnitude. real 4 mag   SPECT_FLUX_VALUE
k_m_40 twomass_xsc 2MASS K 40 arcsec radius circular aperture magnitude. real 4 mag   SPECT_FLUX_VALUE
k_m_5 twomass_xsc 2MASS K 5 arcsec radius circular aperture magnitude. real 4 mag   SPECT_FLUX_VALUE
k_m_50 twomass_xsc 2MASS K 50 arcsec radius circular aperture magnitude. real 4 mag   SPECT_FLUX_VALUE
k_m_60 twomass_xsc 2MASS K 60 arcsec radius circular aperture magnitude. real 4 mag   SPECT_FLUX_VALUE
k_m_7 twomass_xsc 2MASS K 7 arcsec radius circular aperture magnitude. real 4 mag   SPECT_FLUX_VALUE
k_m_70 twomass_xsc 2MASS K 70 arcsec radius circular aperture magnitude. real 4 mag   SPECT_FLUX_VALUE
k_m_c twomass_xsc 2MASS K Kron circular aperture magnitude. real 4 mag   SPECT_FLUX_VALUE
k_m_e twomass_xsc 2MASS K Kron elliptical aperture magnitude. real 4 mag   SPECT_FLUX_VALUE
k_m_ext twomass_xsc 2MASS K mag from fit extrapolation. real 4 mag   SPECT_FLUX_VALUE
k_m_fc twomass_xsc 2MASS K fiducial Kron circular magnitude. real 4 mag   SPECT_FLUX_VALUE
k_m_fe twomass_xsc 2MASS K fiducial Kron ell. mag aperture magnitude. real 4 mag   SPECT_FLUX_VALUE
k_m_i20c twomass_xsc 2MASS K 20mag/sq." isophotal circular ap. magnitude. real 4 mag   SPECT_FLUX_VALUE
k_m_i20e twomass_xsc 2MASS K 20mag/sq." isophotal elliptical ap. magnitude. real 4 mag   SPECT_FLUX_VALUE
k_m_i21c twomass_xsc 2MASS K 21mag/sq." isophotal circular ap. magnitude. real 4 mag   SPECT_FLUX_VALUE
k_m_i21e twomass_xsc 2MASS K 21mag/sq." isophotal elliptical ap. magnitude. real 4 mag   SPECT_FLUX_VALUE
k_m_j21fc twomass_xsc 2MASS K 21mag/sq." isophotal fiducial circ. ap. mag. real 4 mag   SPECT_FLUX_VALUE
k_m_j21fe twomass_xsc 2MASS K 21mag/sq." isophotal fiducial ell. ap. magnitude. real 4 mag   SPECT_FLUX_VALUE
k_m_k20fc twomass_xsc 2MASS K 20mag/sq." isophotal fiducial circ. ap. mag. real 4 mag   SPECT_FLUX_VALUE
k_m_k20fe twomass_xsc 2MASS K 20mag/sq." isophotal fiducial ell. ap. magnitude. real 4 mag   SPECT_FLUX_VALUE
k_m_stdap twomass_psc 2MASS Ks-band "standard" aperture magnitude. real 4 mag   SPECT_FLUX_VALUE
k_m_sys twomass_xsc 2MASS K system photometry magnitude. real 4 mag   SPECT_FLUX_VALUE
k_mnsurfb_eff twomass_xsc 2MASS K mean surface brightness at the half-light radius. real 4 mag   PHOT_SB_GENERAL
k_msig_10 twomass_xsc 2MASS K 1-sigma uncertainty in 10 arcsec circular ap. mag. real 4 mag   ERROR
k_msig_15 twomass_xsc 2MASS K 1-sigma uncertainty in 15 arcsec circular ap. mag. real 4 mag   ERROR
k_msig_20 twomass_xsc 2MASS K 1-sigma uncertainty in 20 arcsec circular ap. mag. real 4 mag   ERROR
k_msig_25 twomass_xsc 2MASS K 1-sigma uncertainty in 25 arcsec circular ap. mag. real 4 mag   ERROR
k_msig_30 twomass_xsc 2MASS K 1-sigma uncertainty in 30 arcsec circular ap. mag. real 4 mag   ERROR
k_msig_40 twomass_xsc 2MASS K 1-sigma uncertainty in 40 arcsec circular ap. mag. real 4 mag   ERROR
k_msig_5 twomass_xsc 2MASS K 1-sigma uncertainty in 5 arcsec circular ap. mag. real 4 mag   ERROR
k_msig_50 twomass_xsc 2MASS K 1-sigma uncertainty in 50 arcsec circular ap. mag. real 4 mag   ERROR
k_msig_60 twomass_xsc 2MASS K 1-sigma uncertainty in 60 arcsec circular ap. mag. real 4 mag   ERROR
k_msig_7 twomass_xsc 2MASS K 1-sigma uncertainty in 7 arcsec circular ap. mag. real 4 mag   ERROR
k_msig_70 twomass_xsc 2MASS K 1-sigma uncertainty in 70 arcsec circular ap. mag. real 4 mag   ERROR
k_msig_c twomass_xsc 2MASS K 1-sigma uncertainty in Kron circular mag. real 4 mag   ERROR
k_msig_e twomass_xsc 2MASS K 1-sigma uncertainty in Kron elliptical mag. real 4 mag   ERROR
k_msig_ext twomass_xsc 2MASS K 1-sigma uncertainty in mag from fit extrapolation. real 4 mag   ERROR
k_msig_fc twomass_xsc 2MASS K 1-sigma uncertainty in fiducial Kron circ. mag. real 4 mag   ERROR
k_msig_fe twomass_xsc 2MASS K 1-sigma uncertainty in fiducial Kron ell. mag. real 4 mag   ERROR
k_msig_i20c twomass_xsc 2MASS K 1-sigma uncertainty in 20mag/sq." iso. circ. mag. real 4 mag   ERROR
k_msig_i20e twomass_xsc 2MASS K 1-sigma uncertainty in 20mag/sq." iso. ell. mag. real 4 mag   ERROR
k_msig_i21c twomass_xsc 2MASS K 1-sigma uncertainty in 21mag/sq." iso. circ. mag. real 4 mag   ERROR
k_msig_i21e twomass_xsc 2MASS K 1-sigma uncertainty in 21mag/sq." iso. ell. mag. real 4 mag   ERROR
k_msig_j21fc twomass_xsc 2MASS K 1-sigma uncertainty in 21mag/sq." iso.fid.circ.mag. real 4 mag   ERROR
k_msig_j21fe twomass_xsc 2MASS K 1-sigma uncertainty in 21mag/sq." iso.fid.ell.mag. real 4 mag   ERROR
k_msig_k20fc twomass_xsc 2MASS K 1-sigma uncertainty in 20mag/sq." iso.fid.circ. mag. real 4 mag   ERROR
k_msig_k20fe twomass_xsc 2MASS K 1-sigma uncertainty in 20mag/sq." iso.fid.ell.mag. real 4 mag   ERROR
k_msig_stdap twomass_psc 2MASS Uncertainty in the Ks-band standard aperture magnitude. real 4 mag   SPECT_FLUX_VALUE
k_msig_sys twomass_xsc 2MASS K 1-sigma uncertainty in system photometry mag. real 4 mag   ERROR
k_msigcom twomass_psc 2MASS Combined, or total photometric uncertainty for the default Ks-band magnitude. real 4 mag   SPECT_FLUX_VALUE
k_msnr10 twomass_scn 2MASS The estimated Ks-band magnitude at which SNR=10 is achieved for this scan. real 4 mag   SPECT_FLUX_VALUE
k_n_snr10 twomass_scn 2MASS Number of point sources at Ks-band with SNR>10 (instrumental mag <=14.3) int 4     NUMBER
k_pchi twomass_xsc 2MASS K chi^2 of fit to rad. profile (LCSB: alpha scale len). real 4     FIT_PARAM_VALUE
k_peak twomass_xsc 2MASS K peak pixel brightness. real 4 mag   PHOT_SB_GENERAL
k_perc_darea twomass_xsc 2MASS K 5-sigma to 3-sigma percent area change. smallint 2     FIT_PARAM
k_phi twomass_xsc 2MASS K angle to 3-sigma major axis (E of N). smallint 2 degrees   POS_POS-ANG
k_psfchi twomass_psc 2MASS Reduced chi-squared goodness-of-fit value for the Ks-band profile-fit photometry made on the 1.3 s "Read_2" exposures. real 4     FIT_PARAM_VALUE
k_psp twomass_scn 2MASS Ks-band photometric sensitivity paramater (PSP). real 4     INST_SENSITIVITY
k_pts_noise twomass_scn 2MASS Base-10 logarithm of the mode of the noise distribution for all point source detections in the scan, where the noise is estimated from the measured Ks-band photometric errors and is expressed in units of mJy. real 4     INST_NOISE
k_r_c twomass_xsc 2MASS K Kron circular aperture radius. real 4 arcsec   EXTENSION_RAD
k_r_e twomass_xsc 2MASS K Kron elliptical aperture semi-major axis. real 4 arcsec   EXTENSION_RAD
k_r_eff twomass_xsc 2MASS K half-light (integrated half-flux point) radius. real 4 arcsec   EXTENSION_RAD
k_r_i20c twomass_xsc 2MASS K 20mag/sq." isophotal circular aperture radius. real 4 arcsec   EXTENSION_RAD
k_r_i20e twomass_xsc 2MASS K 20mag/sq." isophotal elliptical ap. semi-major axis. real 4 arcsec   EXTENSION_RAD
k_r_i21c twomass_xsc 2MASS K 21mag/sq." isophotal circular aperture radius. real 4 arcsec   EXTENSION_RAD
k_r_i21e twomass_xsc 2MASS K 21mag/sq." isophotal elliptical ap. semi-major axis. real 4 arcsec   EXTENSION_RAD
k_resid_ann twomass_xsc 2MASS K residual annulus background median. real 4 DN   CODE_MISC
k_sc_1mm twomass_xsc 2MASS K 1st moment (score) (LCSB: super blk 2,4,8 SNR). real 4     CODE_MISC
k_sc_2mm twomass_xsc 2MASS K 2nd moment (score) (LCSB: SNRMAX - super SNR max). real 4     CODE_MISC
k_sc_msh twomass_xsc 2MASS K median shape score. real 4     CODE_MISC
k_sc_mxdn twomass_xsc 2MASS K mxdn (score) (LCSB: BSNR - block/smoothed SNR). real 4     CODE_MISC
k_sc_r1 twomass_xsc 2MASS K r1 (score). real 4     CODE_MISC
k_sc_r23 twomass_xsc 2MASS K r23 (score) (LCSB: TSNR - integrated SNR for r=15). real 4     CODE_MISC
k_sc_sh twomass_xsc 2MASS K shape (score). real 4     CODE_MISC
k_sc_vint twomass_xsc 2MASS K vint (score). real 4     CODE_MISC
k_sc_wsh twomass_xsc 2MASS K wsh (score) (LCSB: PSNR - peak raw SNR). real 4     CODE_MISC
k_seetrack twomass_xsc 2MASS K band seetracking score. real 4     CODE_MISC
k_sh0 twomass_xsc 2MASS K ridge shape (LCSB: BSNR limit). real 4     FIT_PARAM
k_shape_avg twomass_scn 2MASS Ks-band average seeing shape for scan. real 4     INST_SEEING
k_shape_rms twomass_scn 2MASS RMS-error of Ks-band average seeing shape. real 4     INST_SEEING
k_sig_sh0 twomass_xsc 2MASS K ridge shape sigma (LCSB: B2SNR limit). real 4     FIT_PARAM
k_snr twomass_psc 2MASS Ks-band "scan" signal-to-noise ratio. real 4 mag   INST_NOISE
k_subst2 twomass_xsc 2MASS K residual background #2 (score). real 4     CODE_MISC
k_zp_ap twomass_scn 2MASS Photometric zero-point for Ks-band aperture photometry. real 4 mag   PHOT_ZP
k_zperr_ap twomass_scn 2MASS RMS-error of zero-point for Ks-band aperture photometry real 4 mag   FIT_ERROR
kAperMag3 calSourceEpochs, calSourceMeans, commSource, dxsSource, lasSource, udsSource WSA Extended source K mag (2.0 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG
kAperMag3Err calSourceEpochs, calSourceMeans, commSource, dxsSource, lasSource, udsSource WSA Error in extended source K mag (2.0 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR
kAperMag4 calSourceEpochs, calSourceMeans, commSource, dxsSource, lasSource, udsSource WSA Extended source K mag (2.8 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG
kAperMag4Err calSourceEpochs, calSourceMeans, commSource, dxsSource, lasSource, udsSource WSA Error in extended source K mag (2.8 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR
kAperMag6 calSourceEpochs, calSourceMeans, commSource, dxsSource, lasSource, udsSource WSA Extended source K mag (5.7 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG
kAperMag6Err calSourceEpochs, calSourceMeans, commSource, dxsSource, lasSource, udsSource WSA Error in extended source K mag (5.7 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR
kClass calSourceEpochs, commSource, dxsSource, dxsSourceRemeasurement, lasSource, lasSourceRemeasurement, udsSource, udsSourceRemeasurement WSA discrete image classification flag in K smallint 2   -9999 CLASS_MISC
kClassStat calSourceEpochs, commSource, dxsSource, dxsSourceRemeasurement, lasSource, lasSourceRemeasurement, udsSource, udsSourceRemeasurement WSA N(0,1) stellarness-of-profile statistic in K real 4   -0.9999995e9 STAT_PROP
kDeblend calSourceEpochs, commSource, dxsSource, dxsSourceRemeasurement, lasSource, lasSourceRemeasurement, udsSource, udsSourceRemeasurement WSA flag indicating parent/child relation in K int 4   -99999999 CODE_MISC
kEll calSourceEpochs, commSource, dxsSource, dxsSourceRemeasurement, lasSource, lasSourceRemeasurement, udsSource, udsSourceRemeasurement WSA 1-b/a, where a/b=semi-major/minor axes in K real 4   -0.9999995e9 PHYS_ELLIPTICITY
keNum calMergeLogEpochs, commMergeLog, dxsMergeLog, lasMergeLog, udsMergeLog WSA the extension number of this K frame tinyint 1     NUMBER
kErrBits calSourceEpochs, commSource, dxsSource, dxsSourceRemeasurement, lasSource, lasSourceRemeasurement, udsSource, udsSourceRemeasurement WSA processing warning/error bitwise flags in K int 4   -99999999 CODE_MISC
kEta calSourceEpochs, commSource, dxsSource, lasSource, udsSource WSA Offset of K 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.
kGausig calSourceEpochs, commSource, dxsSource, dxsSourceRemeasurement, lasSource, lasSourceRemeasurement, udsSource, udsSourceRemeasurement WSA RMS of axes of ellipse fit in K real 4 pixels -0.9999995e9 MORPH_PARAM
kHallMag calSourceEpochs, calSourceMeans, commSource, dxsSource, lasSource, udsSource WSA Point source K mag real 4 mag -0.9999995e9 PHOT_MAG
kHallMagErr calSourceEpochs, calSourceMeans, commSource, dxsSource, lasSource, udsSource WSA Error in point source K mag real 4 mag -0.9999995e9 ERROR
kMag CurrentStdStarInfo, PreviousStdStarInfo WSA K band total magnitude of star (from external sources if primary) real 4 mag   PHOT_INT-MAG
kMag dxsSourceRemeasurement, lasSourceRemeasurement, udsSourceRemeasurement WSA K mag (as appropriate for this merged source) real 4 mag -0.9999995e9 PHOT_MAG
kMagErr CurrentStdStarInfo, PreviousStdStarInfo WSA K band magnitude error of star real 4 mag   ERROR
kMagErr dxsSourceRemeasurement, lasSourceRemeasurement, udsSourceRemeasurement WSA Error in K mag real 4 mag -0.9999995e9 ERROR
kmfID calMergeLogEpochs, commMergeLog, dxsMergeLog, udsMergeLog WSA the UID of the relevant K combiframe bigint 8     ID_FRAME
kmfID lasMergeLog WSA the UID of the relevant K multiframe bigint 8     ID_FRAME
kObjID calSourceEpochs, commSource, dxsSource, lasSource, udsSource WSA the UID of the K detection bigint 8   -99999999 ID_NUMBER
kObjID dxsSourceRemeasurement, lasSourceRemeasurement, udsSourceRemeasurement WSA the UID of the K remeasurement bigint 8   -99999999 ID_NUMBER
kPA calSourceEpochs, commSource, dxsSource, dxsSourceRemeasurement, lasSource, lasSourceRemeasurement, udsSource, udsSourceRemeasurement WSA ellipse fit celestial orientation in K real 4 Degrees -0.9999995e9 POS_POS-ANG
kPetroMag calSourceEpochs, calSourceMeans, commSource, dxsSource, lasSource, udsSource WSA Extended source K mag (Petrosian) real 4 mag -0.9999995e9 PHOT_MAG
kPetroMagErr calSourceEpochs, calSourceMeans, commSource, dxsSource, lasSource, udsSource WSA Error in extended source K mag (Petrosian) real 4 mag -0.9999995e9 ERROR
kppErrBits calSourceEpochs, commSource, dxsSource, dxsSourceRemeasurement, lasSource, lasSourceRemeasurement, udsSource, udsSourceRemeasurement WSA additional WFAU post-processing error bits in K int 4   -99999999 CODE_MISC
kPsfMag calSourceEpochs, calSourceMeans, commSource, dxsSource, lasSource, udsSource WSA Point source profile-fitted K mag real 4 mag -0.9999995e9 PHOT_MAG
kPsfMagErr calSourceEpochs, calSourceMeans, commSource, dxsSource, lasSource, udsSource WSA Error in point source profile-fitted K mag real 4 mag -0.9999995e9 ERROR
kronFlux calDetection, commDetection, dxsDetection, dxsListRemeasurement, gcsDetection, gcsListRemeasurement, gpsDetection, gpsListRemeasurement, lasDetection, lasListRemeasurement, udsDetection, udsListRemeasurement WSA flux within circular aperture to k × r_k ; k = 2 {catalogue TType keyword: Kron_flux} real 4 ADU   PHOT_INTENSITY_ADU
kronFluxErr calDetection, commDetection, dxsDetection, dxsListRemeasurement, gcsDetection, gcsListRemeasurement, gpsDetection, gpsListRemeasurement, lasDetection, lasListRemeasurement, udsDetection, udsListRemeasurement WSA error on Kron flux {catalogue TType keyword: Kron_flux_err} real 4 ADU   ERROR
kronMag calDetection, commDetection, dxsDetection, dxsListRemeasurement, gcsDetection, gcsListRemeasurement, gpsDetection, gpsListRemeasurement, lasDetection, lasListRemeasurement, udsDetection, udsListRemeasurement WSA Calibrated Kron magnitude within circular aperture r_k real 4 mag   PHOT_INT-MAG
kronMagErr calDetection, commDetection, dxsDetection, dxsListRemeasurement, gcsDetection, gcsListRemeasurement, gpsDetection, gpsListRemeasurement, lasDetection, lasListRemeasurement, udsDetection, udsListRemeasurement WSA error on calibrated Kron magnitude real 4 mag   ERROR
kronRad calDetection, commDetection, dxsDetection, dxsListRemeasurement, gcsDetection, gcsListRemeasurement, gpsDetection, gpsListRemeasurement, lasDetection, lasListRemeasurement, udsDetection, udsListRemeasurement WSA r_k as defined in Bertin and Arnouts 1996 A&A Supp 117 393 {catalogue TType keyword: Kron_radius} real 4 pixels   EXTENSION_RAD
kSeqNum calSourceEpochs, commSource, dxsSource, lasSource, udsSource WSA the running number of the K detection int 4   -99999999 ID_NUMBER
kSeqNum dxsSourceRemeasurement, lasSourceRemeasurement, udsSourceRemeasurement WSA the running number of the K remeasurement int 4   -99999999 ID_NUMBER
kSerMag2D calSourceEpochs, calSourceMeans, commSource, dxsSource, lasSource, udsSource WSA Extended source K mag (profile-fitted) real 4 mag -0.9999995e9 PHOT_MAG
kSerMag2DErr calSourceEpochs, calSourceMeans, commSource, dxsSource, lasSource, udsSource WSA Error in extended source K mag (profile-fitted) real 4 mag -0.9999995e9 ERROR
kXi calSourceEpochs, commSource, dxsSource, lasSource, udsSource WSA Offset of K 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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27/01/2009