WSA Browser

Glossary of WSA attributes

This Glossary alphabetically lists all attributes used in the UKIDSSDR5 database(s) held in the WSA. If you would like to have more information about the schema tables please use the UKIDSSDR5 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

J

Name Schema Table Database Description Type Length Unit Default Value Unified Content Descriptor

j_1AperMag3 lasExtendedSource, lasPointSource, lasYJHKsource, reliableLasPointSource WSA Default point/extended source 1st epoch J aperture corrected mag (2.0 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG

j_1AperMag3 lasSource WSA Default point/extended source 1st epoch J aperture corrected mag (2.0 arcsec aperture diameter)
If in doubt use this flux estimator real 4 mag -0.9999995e9 PHOT_MAG

j_1AperMag3Err lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableLasPointSource WSA Error in default point/extended source 1st epoch J mag (2.0 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR

j_1AperMag4 lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableLasPointSource WSA Extended source 1st epoch J aperture corrected mag (2.8 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG

j_1AperMag4Err lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableLasPointSource WSA Error in extended source 1st epoch J mag (2.8 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR

j_1AperMag6 lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableLasPointSource WSA Extended source 1st epoch J aperture corrected mag (5.7 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG

j_1AperMag6Err lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableLasPointSource WSA Error in extended source 1st epoch J mag (5.7 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR

j_1Class lasExtendedSource, lasPointSource, lasSource, lasSourceRemeasurement, lasYJHKsource, reliableLasPointSource WSA discrete image classification flag in 1st epoch J smallint 2 -9999 CLASS_MISC

j_1ClassStat lasExtendedSource, lasPointSource, lasSource, lasSourceRemeasurement, lasYJHKsource, reliableLasPointSource WSA N(0,1) stellarness-of-profile statistic in 1st epoch J real 4 -0.9999995e9 STAT_PROP

j_1Deblend lasExtendedSource, lasPointSource, lasSourceRemeasurement, lasYJHKsource, reliableLasPointSource WSA placeholder flag indicating parent/child relation in 1st epoch J int 4 -99999999 CODE_MISC

j_1Deblend lasSource WSA placeholder flag indicating parent/child relation in 1st epoch J int 4 -99999999 CODE_MISC

This CASU pipeline processing source extraction flag is a placeholder only, and is always set to zero in all passbands in the merged source lists. If you need to know when a particular image detection is a component of a deblend or not, test bit 4 of attribute ppErrBits (see corresponding glossary entry) which is set by WFAU's post-processing software based on testing the areal profiles aprof2-8 (these are set by CASU to -1 for deblended components, or positive values for non-deblended detections). We encode this in an information bit of ppErrBits for convenience when querying the merged source tables.

j_1Ell lasExtendedSource, lasPointSource, lasSource, lasSourceRemeasurement, lasYJHKsource, reliableLasPointSource WSA 1-b/a, where a/b=semi-major/minor axes in 1st epoch J real 4 -0.9999995e9 PHYS_ELLIPTICITY

j_1eNum lasMergeLog, lasYJHKmergeLog WSA the extension number of this 1st epoch J frame tinyint 1 NUMBER

j_1ErrBits lasExtendedSource, lasPointSource, lasSourceRemeasurement, lasYJHKsource, reliableLasPointSource WSA processing warning/error bitwise flags in 1st epoch J int 4 -99999999 CODE_MISC

j_1ErrBits lasSource WSA processing warning/error bitwise flags in 1st epoch J 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.

j_1Eta lasExtendedSource, lasPointSource, lasYJHKsource, reliableLasPointSource WSA Offset of 1st epoch J detection from master position (+north/-south) real 4 arcsec -0.9999995e9 POS_EQ_DEC_OFF

j_1Eta lasSource WSA Offset of 1st epoch J 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; also non-survey programmes) or 1.0 (UKIDSS GPS, DXS and UDS) arcseconds is used, the higher value enabling pairing of moving sources when epoch separations may be several years. Such a large association criterion can of course lead to spurious pairings in the merged sources lists (although note that between passband pairs, handshake pairing is done: both passbands must agree that the candidate pair is their nearest neighbour for the pair to propagate through into the merged source table). In order to help filter spurious pairings out, and assuming that large positional offsets between the different passband detections are not expected (e.g. because of source motion, or larger than usual positional uncertainties) then the attributes Xi and Eta can be used to filter any pairings with suspiciously large offsets in one or more bands. For example, for a clean sample of QSOs from the LAS, you might wish to insist that the offsets in the selected sample are all below 1 arcsecond: simply add WHERE clauses into the SQL sample selection script to exclude all Xi and Eta values larger than the threshold you want.

j_1Gausig lasExtendedSource, lasPointSource, lasSource, lasSourceRemeasurement, lasYJHKsource, reliableLasPointSource WSA RMS of axes of ellipse fit in 1st epoch J real 4 pixels -0.9999995e9 MORPH_PARAM

j_1HallMag lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableLasPointSource WSA Total point source 1st epoch J mag real 4 mag -0.9999995e9 PHOT_MAG

j_1HallMagErr lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableLasPointSource WSA Error in total point source 1st epoch J mag real 4 mag -0.9999995e9 ERROR

j_1Mag lasSourceRemeasurement WSA 1st epoch J mag (as appropriate for this merged source) real 4 mag -0.9999995e9 PHOT_MAG

j_1MagErr lasSourceRemeasurement WSA Error in 1st epoch J mag real 4 mag -0.9999995e9 ERROR

j_1mfID lasMergeLog, lasYJHKmergeLog WSA the UID of the relevant 1st epoch J multiframe bigint 8 ID_FRAME

j_1mhExt lasExtendedSource, lasPointSource, lasYJHKsource, reliableLasPointSource WSA Extended source colour J-H (using aperMag3) real 4 mag -0.9999995e9 PHOT_COLOR

j_1mhExt lasSource WSA Extended source colour J-H (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.

j_1mhExtErr lasExtendedSource, lasPointSource, lasYJHKsource, reliableLasPointSource WSA Error on extended source colour J-H real 4 mag -0.9999995e9 ERROR

j_1mhExtErr lasSource WSA Error on extended source colour J-H 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.

j_1mhPnt lasExtendedSource, lasPointSource, lasYJHKsource, reliableLasPointSource WSA Point source colour J-H (using aperMag3) real 4 mag -0.9999995e9 PHOT_COLOR

j_1mhPnt lasSource WSA Point source colour J-H (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.

j_1mhPntErr lasExtendedSource, lasPointSource, lasYJHKsource, reliableLasPointSource WSA Error on point source colour J-H real 4 mag -0.9999995e9 ERROR

j_1mhPntErr lasSource WSA Error on point source colour J-H 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.

j_1ObjID lasExtendedSource, lasPointSource, lasYJHKsource, reliableLasPointSource WSA DEPRECATED (do not use) bigint 8 -99999999 ID_NUMBER

j_1ObjID lasSource, lasSourceRemeasurement WSA DEPRECATED (do not use) bigint 8 -99999999 ID_NUMBER

This attribute is included in source tables for historical reasons, but it's use is not recommended unless you really know what you are doing. In general, if you need to look up detection table attributes for a source in a given passband that are not in the source table, you should make an SQL join between source, mergelog and detection using the primary key attribute frameSetID and combination multiframeID, extNum, seqNum to associate related rows between the three tables. See the Q&A example SQL for more information.

j_1PA lasExtendedSource, lasPointSource, lasSource, lasSourceRemeasurement, lasYJHKsource, reliableLasPointSource WSA ellipse fit celestial orientation in 1st epoch J real 4 Degrees -0.9999995e9 POS_POS-ANG

j_1PetroMag lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableLasPointSource WSA Extended source 1st epoch J mag (Petrosian) real 4 mag -0.9999995e9 PHOT_MAG

j_1PetroMagErr lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableLasPointSource WSA Error in extended source 1st epoch J mag (Petrosian) real 4 mag -0.9999995e9 ERROR

j_1ppErrBits lasExtendedSource, lasPointSource, lasSourceRemeasurement, lasYJHKsource, reliableLasPointSource WSA additional WFAU post-processing error bits in 1st epoch J int 4 0 CODE_MISC

j_1ppErrBits lasSource WSA additional WFAU post-processing error bits in 1st epoch J int 4 0 CODE_MISC

Post-processing error quality bit flags assigned (NB: from UKIDSS DR2 release onwards) in the WSA curation procedure for survey data. From least to most significant byte in the 4-byte integer attribute byte 0 (bits 0 to 7) corresponds to information on generally innocuous conditions that are nonetheless potentially significant as regards the integrity of that detection; byte 1 (bits 8 to 15) corresponds to warnings; byte 2 (bits 16 to 23) corresponds to important warnings; and finally byte 3 (bits 24 to 31) corresponds to severe warnings:

Byte Bit Detection quality issue Threshold or bit mask Applies to

Decimal Hexadecimal

0 4 Deblended 16 0x00000010 LAS, GCS, GPS, DXS

0 6 Bad pixel(s) in default aperture 64 0x00000040 LAS, GCS, GPS, DXS

2 16 Close to saturated 65536 0x00010000 LAS, GCS, GPS

2 19 Possible crosstalk artefact/contamination 524288 0x00080000 LAS, GCS, DXS

2 22 Lies within a dither offset of the stacked frame boundary 4194304 0x00400000 LAS, GCS, GPS, DXS

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.

j_1PsfMag lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableLasPointSource WSA Point source profile-fitted 1st epoch J mag real 4 mag -0.9999995e9 PHOT_MAG

j_1PsfMagErr lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableLasPointSource WSA Error in point source profile-fitted 1st epoch J mag real 4 mag -0.9999995e9 ERROR

j_1SeqNum lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableLasPointSource WSA the running number of the 1st epoch J detection int 4 -99999999 ID_NUMBER

j_1SeqNum lasSourceRemeasurement WSA the running number of the 1st epoch J remeasurement int 4 -99999999 ID_NUMBER

j_1SerMag2D lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableLasPointSource WSA Extended source 1st epoch J mag (profile-fitted) real 4 mag -0.9999995e9 PHOT_MAG

j_1SerMag2DErr lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableLasPointSource WSA Error in extended source 1st epoch J mag (profile-fitted) real 4 mag -0.9999995e9 ERROR

j_1Xi lasExtendedSource, lasPointSource, lasYJHKsource, reliableLasPointSource WSA Offset of 1st epoch J detection from master position (+east/-west) real 4 arcsec -0.9999995e9 POS_EQ_RA_OFF

j_1Xi lasSource WSA Offset of 1st epoch J 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; also non-survey programmes) or 1.0 (UKIDSS GPS, DXS and UDS) arcseconds is used, the higher value enabling pairing of moving sources when epoch separations may be several years. Such a large association criterion can of course lead to spurious pairings in the merged sources lists (although note that between passband pairs, handshake pairing is done: both passbands must agree that the candidate pair is their nearest neighbour for the pair to propagate through into the merged source table). In order to help filter spurious pairings out, and assuming that large positional offsets between the different passband detections are not expected (e.g. because of source motion, or larger than usual positional uncertainties) then the attributes Xi and Eta can be used to filter any pairings with suspiciously large offsets in one or more bands. For example, for a clean sample of QSOs from the LAS, you might wish to insist that the offsets in the selected sample are all below 1 arcsecond: simply add WHERE clauses into the SQL sample selection script to exclude all Xi and Eta values larger than the threshold you want.

j_2AperMag3 lasExtendedSource, lasPointSource, lasYJHKsource, reliableLasPointSource WSA Default point/extended source 2nd epoch J aperture corrected mag (2.0 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG

j_2AperMag3 lasSource WSA Default point/extended source 2nd epoch J aperture corrected mag (2.0 arcsec aperture diameter)
If in doubt use this flux estimator real 4 mag -0.9999995e9 PHOT_MAG

j_2AperMag3Err lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableLasPointSource WSA Error in default point/extended source 2nd epoch J mag (2.0 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR

j_2AperMag4 lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableLasPointSource WSA Extended source 2nd epoch J aperture corrected mag (2.8 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG

j_2AperMag4Err lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableLasPointSource WSA Error in extended source 2nd epoch J mag (2.8 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR

j_2AperMag6 lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableLasPointSource WSA Extended source 2nd epoch J aperture corrected mag (5.7 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG

j_2AperMag6Err lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableLasPointSource WSA Error in extended source 2nd epoch J mag (5.7 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR

j_2Class lasExtendedSource, lasPointSource, lasSource, lasSourceRemeasurement, lasYJHKsource, reliableLasPointSource WSA discrete image classification flag in 2nd epoch J smallint 2 -9999 CLASS_MISC

j_2ClassStat lasExtendedSource, lasPointSource, lasSource, lasSourceRemeasurement, lasYJHKsource, reliableLasPointSource WSA N(0,1) stellarness-of-profile statistic in 2nd epoch J real 4 -0.9999995e9 STAT_PROP

j_2Deblend lasExtendedSource, lasPointSource, lasSourceRemeasurement, lasYJHKsource, reliableLasPointSource WSA placeholder flag indicating parent/child relation in 2nd epoch J int 4 -99999999 CODE_MISC

j_2Deblend lasSource WSA placeholder flag indicating parent/child relation in 2nd epoch J int 4 -99999999 CODE_MISC

This CASU pipeline processing source extraction flag is a placeholder only, and is always set to zero in all passbands in the merged source lists. If you need to know when a particular image detection is a component of a deblend or not, test bit 4 of attribute ppErrBits (see corresponding glossary entry) which is set by WFAU's post-processing software based on testing the areal profiles aprof2-8 (these are set by CASU to -1 for deblended components, or positive values for non-deblended detections). We encode this in an information bit of ppErrBits for convenience when querying the merged source tables.

j_2Ell lasExtendedSource, lasPointSource, lasSource, lasSourceRemeasurement, lasYJHKsource, reliableLasPointSource WSA 1-b/a, where a/b=semi-major/minor axes in 2nd epoch J real 4 -0.9999995e9 PHYS_ELLIPTICITY

j_2eNum lasMergeLog, lasYJHKmergeLog WSA the extension number of this 2nd epoch J frame tinyint 1 NUMBER

j_2ErrBits lasExtendedSource, lasPointSource, lasSourceRemeasurement, lasYJHKsource, reliableLasPointSource WSA processing warning/error bitwise flags in 2nd epoch J int 4 -99999999 CODE_MISC

j_2ErrBits lasSource WSA processing warning/error bitwise flags in 2nd epoch J 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.

j_2Eta lasExtendedSource, lasPointSource, lasYJHKsource, reliableLasPointSource WSA Offset of 2nd epoch J detection from master position (+north/-south) real 4 arcsec -0.9999995e9 POS_EQ_DEC_OFF

j_2Eta lasSource WSA Offset of 2nd epoch J 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; also non-survey programmes) or 1.0 (UKIDSS GPS, DXS and UDS) arcseconds is used, the higher value enabling pairing of moving sources when epoch separations may be several years. Such a large association criterion can of course lead to spurious pairings in the merged sources lists (although note that between passband pairs, handshake pairing is done: both passbands must agree that the candidate pair is their nearest neighbour for the pair to propagate through into the merged source table). In order to help filter spurious pairings out, and assuming that large positional offsets between the different passband detections are not expected (e.g. because of source motion, or larger than usual positional uncertainties) then the attributes Xi and Eta can be used to filter any pairings with suspiciously large offsets in one or more bands. For example, for a clean sample of QSOs from the LAS, you might wish to insist that the offsets in the selected sample are all below 1 arcsecond: simply add WHERE clauses into the SQL sample selection script to exclude all Xi and Eta values larger than the threshold you want.

j_2Gausig lasExtendedSource, lasPointSource, lasSource, lasSourceRemeasurement, lasYJHKsource, reliableLasPointSource WSA RMS of axes of ellipse fit in 2nd epoch J real 4 pixels -0.9999995e9 MORPH_PARAM

j_2HallMag lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableLasPointSource WSA Total point source 2nd epoch J mag real 4 mag -0.9999995e9 PHOT_MAG

j_2HallMagErr lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableLasPointSource WSA Error in total point source 2nd epoch J mag real 4 mag -0.9999995e9 ERROR

j_2Mag lasSourceRemeasurement WSA 2nd epoch J mag (as appropriate for this merged source) real 4 mag -0.9999995e9 PHOT_MAG

j_2MagErr lasSourceRemeasurement WSA Error in 2nd epoch J mag real 4 mag -0.9999995e9 ERROR

j_2mfID lasMergeLog, lasYJHKmergeLog WSA the UID of the relevant 2nd epoch J multiframe bigint 8 ID_FRAME

j_2mrat twomass_scn 2MASS J-band average 2nd image moment ratio. real 4 FIT_PARAM_VALUE

j_2ObjID lasExtendedSource, lasPointSource, lasYJHKsource, reliableLasPointSource WSA DEPRECATED (do not use) bigint 8 -99999999 ID_NUMBER

j_2ObjID lasSource, lasSourceRemeasurement WSA DEPRECATED (do not use) bigint 8 -99999999 ID_NUMBER

This attribute is included in source tables for historical reasons, but it's use is not recommended unless you really know what you are doing. In general, if you need to look up detection table attributes for a source in a given passband that are not in the source table, you should make an SQL join between source, mergelog and detection using the primary key attribute frameSetID and combination multiframeID, extNum, seqNum to associate related rows between the three tables. See the Q&A example SQL for more information.

j_2PA lasExtendedSource, lasPointSource, lasSource, lasSourceRemeasurement, lasYJHKsource, reliableLasPointSource WSA ellipse fit celestial orientation in 2nd epoch J real 4 Degrees -0.9999995e9 POS_POS-ANG

j_2PetroMag lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableLasPointSource WSA Extended source 2nd epoch J mag (Petrosian) real 4 mag -0.9999995e9 PHOT_MAG

j_2PetroMagErr lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableLasPointSource WSA Error in extended source 2nd epoch J mag (Petrosian) real 4 mag -0.9999995e9 ERROR

j_2ppErrBits lasExtendedSource, lasPointSource, lasSourceRemeasurement, lasYJHKsource, reliableLasPointSource WSA additional WFAU post-processing error bits in 2nd epoch J int 4 0 CODE_MISC

j_2ppErrBits lasSource WSA additional WFAU post-processing error bits in 2nd epoch J int 4 0 CODE_MISC

Post-processing error quality bit flags assigned (NB: from UKIDSS DR2 release onwards) in the WSA curation procedure for survey data. From least to most significant byte in the 4-byte integer attribute byte 0 (bits 0 to 7) corresponds to information on generally innocuous conditions that are nonetheless potentially significant as regards the integrity of that detection; byte 1 (bits 8 to 15) corresponds to warnings; byte 2 (bits 16 to 23) corresponds to important warnings; and finally byte 3 (bits 24 to 31) corresponds to severe warnings:

Byte Bit Detection quality issue Threshold or bit mask Applies to

Decimal Hexadecimal

0 4 Deblended 16 0x00000010 LAS, GCS, GPS, DXS

0 6 Bad pixel(s) in default aperture 64 0x00000040 LAS, GCS, GPS, DXS

2 16 Close to saturated 65536 0x00010000 LAS, GCS, GPS

2 19 Possible crosstalk artefact/contamination 524288 0x00080000 LAS, GCS, DXS

2 22 Lies within a dither offset of the stacked frame boundary 4194304 0x00400000 LAS, GCS, GPS, DXS

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.

j_2PsfMag lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableLasPointSource WSA Point source profile-fitted 2nd epoch J mag real 4 mag -0.9999995e9 PHOT_MAG

j_2PsfMagErr lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableLasPointSource WSA Error in point source profile-fitted 2nd epoch J mag real 4 mag -0.9999995e9 ERROR

j_2SeqNum lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableLasPointSource WSA the running number of the 2nd epoch J detection int 4 -99999999 ID_NUMBER

j_2SeqNum lasSourceRemeasurement WSA the running number of the 2nd epoch J remeasurement int 4 -99999999 ID_NUMBER

j_2SerMag2D lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableLasPointSource WSA Extended source 2nd epoch J mag (profile-fitted) real 4 mag -0.9999995e9 PHOT_MAG

j_2SerMag2DErr lasExtendedSource, lasPointSource, lasSource, lasYJHKsource, reliableLasPointSource WSA Error in extended source 2nd epoch J mag (profile-fitted) real 4 mag -0.9999995e9 ERROR

j_2Xi lasExtendedSource, lasPointSource, lasYJHKsource, reliableLasPointSource WSA Offset of 2nd epoch J detection from master position (+east/-west) real 4 arcsec -0.9999995e9 POS_EQ_RA_OFF

j_2Xi lasSource WSA Offset of 2nd epoch J 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; also non-survey programmes) or 1.0 (UKIDSS GPS, DXS and UDS) arcseconds is used, the higher value enabling pairing of moving sources when epoch separations may be several years. Such a large association criterion can of course lead to spurious pairings in the merged sources lists (although note that between passband pairs, handshake pairing is done: both passbands must agree that the candidate pair is their nearest neighbour for the pair to propagate through into the merged source table). In order to help filter spurious pairings out, and assuming that large positional offsets between the different passband detections are not expected (e.g. because of source motion, or larger than usual positional uncertainties) then the attributes Xi and Eta can be used to filter any pairings with suspiciously large offsets in one or more bands. For example, for a clean sample of QSOs from the LAS, you might wish to insist that the offsets in the selected sample are all below 1 arcsecond: simply add WHERE clauses into the SQL sample selection script to exclude all Xi and Eta values larger than the threshold you want.

j_5sig_ba twomass_xsc 2MASS J minor/major axis ratio fit to the 5-sigma isophote. real 4 PHYS_AXIS-RATIO

j_5sig_phi twomass_xsc 2MASS J angle to 5-sigma major axis (E of N). smallint 2 degrees ERROR

j_5surf twomass_xsc 2MASS J central surface brightness (r<=5). real 4 mag PHOT_SB_GENERAL

j_ba twomass_xsc 2MASS J minor/major axis ratio fit to the 3-sigma isophote. real 4 PHYS_AXIS-RATIO

j_back twomass_xsc 2MASS J coadd median background. real 4 CODE_MISC

j_bisym_chi twomass_xsc 2MASS J bi-symmetric cross-correlation chi. real 4 FIT_PARAM_VALUE

j_bisym_rat twomass_xsc 2MASS J bi-symmetric flux ratio. real 4 PHOT_FLUX_RATIO

j_bndg_amp twomass_xsc 2MASS J banding maximum FT amplitude on this side of coadd. real 4 DN FIT_PARAM_VALUE

j_bndg_per twomass_xsc 2MASS J banding Fourier Transf. period on this side of coadd. int 4 arcsec FIT_PARAM_VALUE

j_chif_ellf twomass_xsc 2MASS J % chi-fraction for elliptical fit to 3-sig isophote. real 4 FIT_PARAM_VALUE

j_cmsig twomass_psc 2MASS Corrected photometric uncertainty for the default J-band magnitude. real 4 mag SPECT_FLUX_VALUE

j_con_indx twomass_xsc 2MASS J concentration index r_75%/r_25%. real 4 PHYS_CONCENT_INDEX

j_d_area twomass_xsc 2MASS J 5-sigma to 3-sigma differential area. smallint 2 FIT_RESIDUAL

j_flg_10 twomass_xsc 2MASS J confusion flag for 10 arcsec circular ap. mag. smallint 2 CODE_MISC

j_flg_15 twomass_xsc 2MASS J confusion flag for 15 arcsec circular ap. mag. smallint 2 CODE_MISC

j_flg_20 twomass_xsc 2MASS J confusion flag for 20 arcsec circular ap. mag. smallint 2 CODE_MISC

j_flg_25 twomass_xsc 2MASS J confusion flag for 25 arcsec circular ap. mag. smallint 2 CODE_MISC

j_flg_30 twomass_xsc 2MASS J confusion flag for 30 arcsec circular ap. mag. smallint 2 CODE_MISC

j_flg_40 twomass_xsc 2MASS J confusion flag for 40 arcsec circular ap. mag. smallint 2 CODE_MISC

j_flg_5 twomass_xsc 2MASS J confusion flag for 5 arcsec circular ap. mag. smallint 2 CODE_MISC

j_flg_50 twomass_xsc 2MASS J confusion flag for 50 arcsec circular ap. mag. smallint 2 CODE_MISC

j_flg_60 twomass_xsc 2MASS J confusion flag for 60 arcsec circular ap. mag. smallint 2 CODE_MISC

j_flg_7 twomass_xsc 2MASS J confusion flag for 7 arcsec circular ap. mag. smallint 2 CODE_MISC

j_flg_70 twomass_xsc 2MASS J confusion flag for 70 arcsec circular ap. mag. smallint 2 CODE_MISC

j_flg_c twomass_xsc 2MASS J confusion flag for Kron circular mag. smallint 2 CODE_MISC

j_flg_e twomass_xsc 2MASS J confusion flag for Kron elliptical mag. smallint 2 CODE_MISC

j_flg_fc twomass_xsc 2MASS J confusion flag for fiducial Kron circ. mag. smallint 2 CODE_MISC

j_flg_fe twomass_xsc 2MASS J confusion flag for fiducial Kron ell. mag. smallint 2 CODE_MISC

j_flg_i20c twomass_xsc 2MASS J confusion flag for 20mag/sq." iso. circ. mag. smallint 2 CODE_MISC

j_flg_i20e twomass_xsc 2MASS J confusion flag for 20mag/sq." iso. ell. mag. smallint 2 CODE_MISC

j_flg_i21c twomass_xsc 2MASS J confusion flag for 21mag/sq." iso. circ. mag. smallint 2 CODE_MISC

j_flg_i21e twomass_xsc 2MASS J confusion flag for 21mag/sq." iso. ell. mag. smallint 2 CODE_MISC

j_flg_j21fc twomass_xsc 2MASS J confusion flag for 21mag/sq." iso. fid. circ. mag. smallint 2 CODE_MISC

j_flg_j21fe twomass_xsc 2MASS J confusion flag for 21mag/sq." iso. fid. ell. mag. smallint 2 CODE_MISC

j_flg_k20fc twomass_xsc 2MASS J confusion flag for 20mag/sq." iso. fid. circ. mag. smallint 2 CODE_MISC

j_flg_k20fe twomass_xsc 2MASS J confusion flag for 20mag/sq." iso. fid. ell. mag. smallint 2 CODE_MISC

j_m twomass_psc 2MASS Default J-band magnitude real 4 mag SPECT_FLUX_VALUE

j_m_10 twomass_xsc 2MASS J 10 arcsec radius circular aperture magnitude. real 4 mag SPECT_FLUX_VALUE

j_m_15 twomass_xsc 2MASS J 15 arcsec radius circular aperture magnitude. real 4 mag SPECT_FLUX_VALUE

j_m_20 twomass_xsc 2MASS J 20 arcsec radius circular aperture magnitude. real 4 mag SPECT_FLUX_VALUE

j_m_25 twomass_xsc 2MASS J 25 arcsec radius circular aperture magnitude. real 4 mag SPECT_FLUX_VALUE

j_m_30 twomass_xsc 2MASS J 30 arcsec radius circular aperture magnitude. real 4 mag SPECT_FLUX_VALUE

j_m_40 twomass_xsc 2MASS J 40 arcsec radius circular aperture magnitude. real 4 mag SPECT_FLUX_VALUE

j_m_5 twomass_xsc 2MASS J 5 arcsec radius circular aperture magnitude. real 4 mag SPECT_FLUX_VALUE

j_m_50 twomass_xsc 2MASS J 50 arcsec radius circular aperture magnitude. real 4 mag SPECT_FLUX_VALUE

j_m_60 twomass_xsc 2MASS J 60 arcsec radius circular aperture magnitude. real 4 mag SPECT_FLUX_VALUE

j_m_7 twomass_xsc 2MASS J 7 arcsec radius circular aperture magnitude. real 4 mag SPECT_FLUX_VALUE

j_m_70 twomass_xsc 2MASS J 70 arcsec radius circular aperture magnitude. real 4 mag SPECT_FLUX_VALUE

j_m_c twomass_xsc 2MASS J Kron circular aperture magnitude. real 4 mag SPECT_FLUX_VALUE

j_m_e twomass_xsc 2MASS J Kron elliptical aperture magnitude. real 4 mag SPECT_FLUX_VALUE

j_m_ext twomass_xsc 2MASS J mag from fit extrapolation. real 4 mag SPECT_FLUX_VALUE

j_m_fc twomass_xsc 2MASS J fiducial Kron circular magnitude. real 4 mag SPECT_FLUX_VALUE

j_m_fe twomass_xsc 2MASS J fiducial Kron ell. mag aperture magnitude. real 4 mag SPECT_FLUX_VALUE

j_m_i20c twomass_xsc 2MASS J 20mag/sq." isophotal circular ap. magnitude. real 4 mag SPECT_FLUX_VALUE

j_m_i20e twomass_xsc 2MASS J 20mag/sq." isophotal elliptical ap. magnitude. real 4 mag SPECT_FLUX_VALUE

j_m_i21c twomass_xsc 2MASS J 21mag/sq." isophotal circular ap. magnitude. real 4 mag SPECT_FLUX_VALUE

j_m_i21e twomass_xsc 2MASS J 21mag/sq." isophotal elliptical ap. magnitude. real 4 mag SPECT_FLUX_VALUE

j_m_j21fc twomass_xsc 2MASS J 21mag/sq." isophotal fiducial circ. ap. mag. real 4 mag SPECT_FLUX_VALUE

j_m_j21fe twomass_xsc 2MASS J 21mag/sq." isophotal fiducial ell. ap. magnitude. real 4 mag SPECT_FLUX_VALUE

j_m_k20fc twomass_xsc 2MASS J 20mag/sq." isophotal fiducial circ. ap. mag. real 4 mag SPECT_FLUX_VALUE

j_m_k20fe twomass_xsc 2MASS J 20mag/sq." isophotal fiducial ell. ap. magnitude. real 4 mag SPECT_FLUX_VALUE

j_m_stdap twomass_psc 2MASS J-band "standard" aperture magnitude. real 4 mag SPECT_FLUX_VALUE

j_m_sys twomass_xsc 2MASS J system photometry magnitude. real 4 mag SPECT_FLUX_VALUE

j_mnsurfb_eff twomass_xsc 2MASS J mean surface brightness at the half-light radius. real 4 mag PHOT_SB_GENERAL

j_msig_10 twomass_xsc 2MASS J 1-sigma uncertainty in 10 arcsec circular ap. mag. real 4 mag ERROR

j_msig_15 twomass_xsc 2MASS J 1-sigma uncertainty in 15 arcsec circular ap. mag. real 4 mag ERROR

j_msig_20 twomass_xsc 2MASS J 1-sigma uncertainty in 20 arcsec circular ap. mag. real 4 mag ERROR

j_msig_25 twomass_xsc 2MASS J 1-sigma uncertainty in 25 arcsec circular ap. mag. real 4 mag ERROR

j_msig_30 twomass_xsc 2MASS J 1-sigma uncertainty in 30 arcsec circular ap. mag. real 4 mag ERROR

j_msig_40 twomass_xsc 2MASS J 1-sigma uncertainty in 40 arcsec circular ap. mag. real 4 mag ERROR

j_msig_5 twomass_xsc 2MASS J 1-sigma uncertainty in 5 arcsec circular ap. mag. real 4 mag ERROR

j_msig_50 twomass_xsc 2MASS J 1-sigma uncertainty in 50 arcsec circular ap. mag. real 4 mag ERROR

j_msig_60 twomass_xsc 2MASS J 1-sigma uncertainty in 60 arcsec circular ap. mag. real 4 mag ERROR

j_msig_7 twomass_xsc 2MASS J 1-sigma uncertainty in 7 arcsec circular ap. mag. real 4 mag ERROR

j_msig_70 twomass_xsc 2MASS J 1-sigma uncertainty in 70 arcsec circular ap. mag. real 4 mag ERROR

j_msig_c twomass_xsc 2MASS J 1-sigma uncertainty in Kron circular mag. real 4 mag ERROR

j_msig_e twomass_xsc 2MASS J 1-sigma uncertainty in Kron elliptical mag. real 4 mag ERROR

j_msig_ext twomass_xsc 2MASS J 1-sigma uncertainty in mag from fit extrapolation. real 4 mag ERROR

j_msig_fc twomass_xsc 2MASS J 1-sigma uncertainty in fiducial Kron circ. mag. real 4 mag ERROR

j_msig_fe twomass_xsc 2MASS J 1-sigma uncertainty in fiducial Kron ell. mag. real 4 mag ERROR

j_msig_i20c twomass_xsc 2MASS J 1-sigma uncertainty in 20mag/sq." iso. circ. mag. real 4 mag ERROR

j_msig_i20e twomass_xsc 2MASS J 1-sigma uncertainty in 20mag/sq." iso. ell. mag. real 4 mag ERROR

j_msig_i21c twomass_xsc 2MASS J 1-sigma uncertainty in 21mag/sq." iso. circ. mag. real 4 mag ERROR

j_msig_i21e twomass_xsc 2MASS J 1-sigma uncertainty in 21mag/sq." iso. ell. mag. real 4 mag ERROR

j_msig_j21fc twomass_xsc 2MASS J 1-sigma uncertainty in 21mag/sq." iso.fid.circ.mag. real 4 mag ERROR

j_msig_j21fe twomass_xsc 2MASS J 1-sigma uncertainty in 21mag/sq." iso.fid.ell.mag. real 4 mag ERROR

j_msig_k20fc twomass_xsc 2MASS J 1-sigma uncertainty in 20mag/sq." iso.fid.circ. mag. real 4 mag ERROR

j_msig_k20fe twomass_xsc 2MASS J 1-sigma uncertainty in 20mag/sq." iso.fid.ell.mag. real 4 mag ERROR

j_msig_stdap twomass_psc 2MASS Uncertainty in the J-band standard aperture magnitude. real 4 mag SPECT_FLUX_VALUE

j_msig_sys twomass_xsc 2MASS J 1-sigma uncertainty in system photometry mag. real 4 mag ERROR

j_msigcom twomass_psc 2MASS Combined, or total photometric uncertainty for the default J-band magnitude. real 4 mag SPECT_FLUX_VALUE

j_msnr10 twomass_scn 2MASS The estimated J-band magnitude at which SNR=10 is achieved for this scan. real 4 mag SPECT_FLUX_VALUE

j_n_snr10 twomass_scn 2MASS Number of point sources at J-band with SNR>10 (instrumental mag <=15.8) int 4 NUMBER

j_pchi twomass_xsc 2MASS J chi^2 of fit to rad. profile (LCSB: alpha scale len). real 4 FIT_PARAM_VALUE

j_peak twomass_xsc 2MASS J peak pixel brightness. real 4 mag PHOT_SB_GENERAL

j_perc_darea twomass_xsc 2MASS J 5-sigma to 3-sigma percent area change. smallint 2 FIT_PARAM

j_phi twomass_xsc 2MASS J angle to 3-sigma major axis (E of N). smallint 2 degrees POS_POS-ANG

j_psfchi twomass_psc 2MASS Reduced chi-squared goodness-of-fit value for the J-band profile-fit photometry made on the 1.3 s "Read_2" exposures. real 4 FIT_PARAM_VALUE

j_psp twomass_scn 2MASS J-band photometric sensitivity paramater (PSP). real 4 INST_SENSITIVITY

j_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 J-band photometric errors and is expressed in units of mJy. real 4 INST_NOISE

j_r_c twomass_xsc 2MASS J Kron circular aperture radius. real 4 arcsec EXTENSION_RAD

j_r_e twomass_xsc 2MASS J Kron elliptical aperture semi-major axis. real 4 arcsec EXTENSION_RAD

j_r_eff twomass_xsc 2MASS J half-light (integrated half-flux point) radius. real 4 arcsec EXTENSION_RAD

j_r_i20c twomass_xsc 2MASS J 20mag/sq." isophotal circular aperture radius. real 4 arcsec EXTENSION_RAD

j_r_i20e twomass_xsc 2MASS J 20mag/sq." isophotal elliptical ap. semi-major axis. real 4 arcsec EXTENSION_RAD

j_r_i21c twomass_xsc 2MASS J 21mag/sq." isophotal circular aperture radius. real 4 arcsec EXTENSION_RAD

j_r_i21e twomass_xsc 2MASS J 21mag/sq." isophotal elliptical ap. semi-major axis. real 4 arcsec EXTENSION_RAD

j_resid_ann twomass_xsc 2MASS J residual annulus background median. real 4 DN CODE_MISC

j_sc_1mm twomass_xsc 2MASS J 1st moment (score) (LCSB: super blk 2,4,8 SNR). real 4 CODE_MISC

j_sc_2mm twomass_xsc 2MASS J 2nd moment (score) (LCSB: SNRMAX - super SNR max). real 4 CODE_MISC

j_sc_msh twomass_xsc 2MASS J median shape score. real 4 CODE_MISC

j_sc_mxdn twomass_xsc 2MASS J mxdn (score) (LCSB: BSNR - block/smoothed SNR). real 4 CODE_MISC

j_sc_r1 twomass_xsc 2MASS J r1 (score). real 4 CODE_MISC

j_sc_r23 twomass_xsc 2MASS J r23 (score) (LCSB: TSNR - integrated SNR for r=15). real 4 CODE_MISC

j_sc_sh twomass_xsc 2MASS J shape (score). real 4 CODE_MISC

j_sc_vint twomass_xsc 2MASS J vint (score). real 4 CODE_MISC

j_sc_wsh twomass_xsc 2MASS J wsh (score) (LCSB: PSNR - peak raw SNR). real 4 CODE_MISC

j_seetrack twomass_xsc 2MASS J band seetracking score. real 4 CODE_MISC

j_sh0 twomass_xsc 2MASS J ridge shape (LCSB: BSNR limit). real 4 FIT_PARAM

j_shape_avg twomass_scn 2MASS J-band average seeing shape for scan. real 4 INST_SEEING

j_shape_rms twomass_scn 2MASS RMS-error of J-band average seeing shape. real 4 INST_SEEING

j_sig_sh0 twomass_xsc 2MASS J ridge shape sigma (LCSB: B2SNR limit). real 4 FIT_PARAM

j_snr twomass_psc 2MASS J-band "scan" signal-to-noise ratio. real 4 mag INST_NOISE

j_subst2 twomass_xsc 2MASS J residual background #2 (score). real 4 CODE_MISC

j_zp_ap twomass_scn 2MASS Photometric zero-point for J-band aperture photometry. real 4 mag PHOT_ZP

jAperMag1 gpsJHKsource, gpsPointSource, gpsSource, reliableGpsPointSource WSA Extended source J aperture corrected mag (1.0 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG

jAperMag1Err gpsJHKsource, gpsPointSource, gpsSource, reliableGpsPointSource WSA Error in extended source J mag (1.0 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR

jAperMag3 dxsJKsource, gcsPointSource, gcsZYJHKsource, gpsJHKsource, gpsPointSource, reliableDxsSource, reliableGcsPointSource, reliableGpsPointSource WSA Default point/extended source J aperture corrected mag (2.0 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG

jAperMag3 dxsSource, gcsSource, gpsSource WSA Default point/extended source J aperture corrected mag (2.0 arcsec aperture diameter)
If in doubt use this flux estimator real 4 mag -0.9999995e9 PHOT_MAG

jAperMag3 reliableUdsSource WSA Default point/extended source J mag, no aperture correction applied real 4 mag -0.9999995e9 PHOT_MAG

jAperMag3 udsSource WSA Default point/extended source J mag, no aperture correction applied
If in doubt use this flux estimator real 4 mag -0.9999995e9 PHOT_MAG

jAperMag3Err dxsJKsource, dxsSource, gcsPointSource, gcsSource, gcsZYJHKsource, gpsJHKsource, gpsPointSource, gpsSource, reliableDxsSource, reliableGcsPointSource, reliableGpsPointSource, reliableUdsSource, udsSource WSA Error in default point/extended source J mag (2.0 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR

jAperMag4 dxsJKsource, dxsSource, gcsPointSource, gcsSource, gcsZYJHKsource, gpsJHKsource, gpsPointSource, gpsSource, reliableDxsSource, reliableGcsPointSource, reliableGpsPointSource WSA Extended source J aperture corrected mag (2.8 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG

jAperMag4 reliableUdsSource, udsSource WSA Extended source J mag, no aperture correction applied real 4 mag -0.9999995e9 PHOT_MAG

jAperMag4Err dxsJKsource, dxsSource, gcsPointSource, gcsSource, gcsZYJHKsource, gpsJHKsource, gpsPointSource, gpsSource, reliableDxsSource, reliableGcsPointSource, reliableGpsPointSource, reliableUdsSource, udsSource WSA Error in extended source J mag (2.8 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR

jAperMag6 dxsJKsource, dxsSource, gcsPointSource, gcsSource, gcsZYJHKsource, reliableDxsSource, reliableGcsPointSource WSA Extended source J aperture corrected mag (5.7 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG

jAperMag6 reliableUdsSource, udsSource WSA Extended source J mag, no aperture correction applied real 4 mag -0.9999995e9 PHOT_MAG

jAperMag6Err dxsJKsource, dxsSource, gcsPointSource, gcsSource, gcsZYJHKsource, reliableDxsSource, reliableGcsPointSource, reliableUdsSource, udsSource WSA Error in extended source J mag (5.7 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR

jaStrat dxsVarFrameSetInfo, udsVarFrameSetInfo WSA Strateva parameter, a, in fit to photometric rms vs magnitude in J band, see Sesar et al. 2007. real 4 -0.9999995e9

The best fit solution to the expected RMS for all objects in the frameset. Objects were binned in ranges of magnitude and the median RMS (after clipping out variable objects using the median-absolute deviation) was calculated. The Strateva function $\zeta(m)>=a+b\,10^{0.4m}+c\,10^{0.8m}$ was fit, where $\zeta(m)$ is the expected RMS as a function of magnitude. The chi-squared and number of degrees of freedom are also calculated. This technique was used in Sesar et al. 2007, AJ, 134, 2236.

jbestAper dxsVariability, udsVariability WSA Best aperture (1-6) for photometric statistics in the J band int 4 -9999

Aperture magnitude (1-6) which gives the lowest RMS for the object. All apertures have the appropriate aperture correction. This can give better values in crowded regions than aperMag3 (see Irwin et al. 2007, MNRAS, 375, 1449)

jbStrat dxsVarFrameSetInfo, udsVarFrameSetInfo WSA Strateva parameter, b, in fit to photometric rms vs magnitude in J band, see Sesar et al. 2007. real 4 -0.9999995e9

The best fit solution to the expected RMS for all objects in the frameset. Objects were binned in ranges of magnitude and the median RMS (after clipping out variable objects using the median-absolute deviation) was calculated. The Strateva function $\zeta(m)>=a+b\,10^{0.4m}+c\,10^{0.8m}$ was fit, where $\zeta(m)$ is the expected RMS as a function of magnitude. The chi-squared and number of degrees of freedom are also calculated. This technique was used in Sesar et al. 2007, AJ, 134, 2236.

jchiSq dxsVarFrameSetInfo, udsVarFrameSetInfo WSA Goodness of fit of Strateva function to photometric data in J band real 4 -0.9999995e9

The best fit solution to the expected RMS for all objects in the frameset. Objects were binned in ranges of magnitude and the median RMS (after clipping out variable objects using the median-absolute deviation) was calculated. The Strateva function $\zeta(m)>=a+b\,10^{0.4m}+c\,10^{0.8m}$ was fit, where $\zeta(m)$ is the expected RMS as a function of magnitude. The chi-squared and number of degrees of freedom are also calculated. This technique was used in Sesar et al. 2007, AJ, 134, 2236.

jchiSqpd dxsVariability, udsVariability WSA 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 and median absolute deviation are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.

jClass dxsJKsource, dxsSource, dxsSourceRemeasurement, gcsPointSource, gcsSource, gcsSourceRemeasurement, gcsZYJHKsource, gpsJHKsource, gpsPointSource, gpsSource, gpsSourceRemeasurement, reliableDxsSource, reliableGcsPointSource, reliableGpsPointSource, reliableUdsSource, udsSource, udsSourceRemeasurement WSA discrete image classification flag in J smallint 2 -9999 CLASS_MISC

jClassStat dxsJKsource, dxsSource, dxsSourceRemeasurement, gcsPointSource, gcsSource, gcsSourceRemeasurement, gcsZYJHKsource, gpsSourceRemeasurement, reliableDxsSource, reliableGcsPointSource, udsSourceRemeasurement WSA N(0,1) stellarness-of-profile statistic in J real 4 -0.9999995e9 STAT_PROP

jClassStat gpsJHKsource, gpsPointSource, gpsSource, reliableGpsPointSource, reliableUdsSource, udsSource WSA S-Extractor classification statistic in J real 4 -0.9999995e9 STAT_PROP

jcStrat dxsVarFrameSetInfo, udsVarFrameSetInfo WSA Strateva parameter, c, in fit to photometric rms vs magnitude in J band, see Sesar et al. 2007. real 4 -0.9999995e9

The best fit solution to the expected RMS for all objects in the frameset. Objects were binned in ranges of magnitude and the median RMS (after clipping out variable objects using the median-absolute deviation) was calculated. The Strateva function $\zeta(m)>=a+b\,10^{0.4m}+c\,10^{0.8m}$ was fit, where $\zeta(m)$ is the expected RMS as a function of magnitude. The chi-squared and number of degrees of freedom are also calculated. This technique was used in Sesar et al. 2007, AJ, 134, 2236.

jdate twomass_psc 2MASS The Julian Date of the source measurement accurate to +-30 seconds. float 8 Julian days TIME_DATE

jdate twomass_scn 2MASS Julian Date at beginning of scan. float 8 Julian days TIME_DATE

jdate twomass_xsc 2MASS Julian date of the source measurement accurate to +-3 minutes. float 8 Julian days TIME_DATE

jDeblend dxsJKsource, dxsSourceRemeasurement, gcsPointSource, gcsSourceRemeasurement, gcsZYJHKsource, gpsJHKsource, gpsPointSource, gpsSource, gpsSourceRemeasurement, reliableDxsSource, reliableGcsPointSource, reliableGpsPointSource, reliableUdsSource, udsSource, udsSourceRemeasurement WSA placeholder flag indicating parent/child relation in J int 4 -99999999 CODE_MISC

jDeblend dxsSource, gcsSource WSA placeholder flag indicating parent/child relation in J int 4 -99999999 CODE_MISC

This CASU pipeline processing source extraction flag is a placeholder only, and is always set to zero in all passbands in the merged source lists. If you need to know when a particular image detection is a component of a deblend or not, test bit 4 of attribute ppErrBits (see corresponding glossary entry) which is set by WFAU's post-processing software based on testing the areal profiles aprof2-8 (these are set by CASU to -1 for deblended components, or positive values for non-deblended detections). We encode this in an information bit of ppErrBits for convenience when querying the merged source tables.

jEll dxsJKsource, dxsSource, dxsSourceRemeasurement, gcsPointSource, gcsSource, gcsSourceRemeasurement, gcsZYJHKsource, gpsJHKsource, gpsPointSource, gpsSource, gpsSourceRemeasurement, reliableDxsSource, reliableGcsPointSource, reliableGpsPointSource, reliableUdsSource, udsSource, udsSourceRemeasurement WSA 1-b/a, where a/b=semi-major/minor axes in J real 4 -0.9999995e9 PHYS_ELLIPTICITY

jeNum dxsJKmergeLog, gpsJHKmergeLog WSA the extension number of this frame tinyint 1 NUMBER

jeNum dxsMergeLog, gcsMergeLog, gcsZYJHKmergeLog, gpsMergeLog, udsMergeLog WSA the extension number of this J frame tinyint 1 NUMBER

jErrBits dxsJKsource, dxsSourceRemeasurement, gcsPointSource, gcsSourceRemeasurement, gcsZYJHKsource, gpsJHKsource, gpsPointSource, gpsSourceRemeasurement, reliableDxsSource, reliableGcsPointSource, reliableGpsPointSource, reliableUdsSource, udsSourceRemeasurement WSA processing warning/error bitwise flags in J int 4 -99999999 CODE_MISC

jErrBits dxsSource, gcsSource WSA processing warning/error bitwise flags in J 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.

jErrBits gpsSource, udsSource WSA processing warning/error bitwise flags in J int 4 -99999999 CODE_MISC

This uses the FLAGS attribute in SE. The individual bit flags that this can be decomposed into are as follows:

Bit Flag Meaning

1 The object has neighbours, bright enough and close enough to significantly bias the MAG_AUTO photometry or bad pixels (more than 10% of photometry affected).

2 The object was originally blended with another

4 At least one pixel is saturated (or very close to)

8 The object is truncated (too close to an image boundary)

16 Object's aperture data are incomplete or corrupted

32 Object's isophotal data are imcomplete or corrupted. This is an old flag inherited from SE v1.0, and is kept for compatability reasons. It doesn't have any consequence for the extracted parameters.

64 Memory overflow occurred during deblending

128 Memory overflow occurred during extraction

jEta dxsJKsource, gcsPointSource, gcsZYJHKsource, gpsJHKsource, gpsPointSource, reliableDxsSource, reliableGcsPointSource, reliableGpsPointSource, reliableUdsSource WSA Offset of J detection from master position (+north/-south) real 4 arcsec -0.9999995e9 POS_EQ_DEC_OFF

jEta dxsSource, gcsSource, gpsSource, udsSource WSA Offset of J 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; also non-survey programmes) or 1.0 (UKIDSS GPS, DXS and UDS) arcseconds is used, the higher value enabling pairing of moving sources when epoch separations may be several years. Such a large association criterion can of course lead to spurious pairings in the merged sources lists (although note that between passband pairs, handshake pairing is done: both passbands must agree that the candidate pair is their nearest neighbour for the pair to propagate through into the merged source table). In order to help filter spurious pairings out, and assuming that large positional offsets between the different passband detections are not expected (e.g. because of source motion, or larger than usual positional uncertainties) then the attributes Xi and Eta can be used to filter any pairings with suspiciously large offsets in one or more bands. For example, for a clean sample of QSOs from the LAS, you might wish to insist that the offsets in the selected sample are all below 1 arcsecond: simply add WHERE clauses into the SQL sample selection script to exclude all Xi and Eta values larger than the threshold you want.

jexpML dxsVarFrameSetInfo, udsVarFrameSetInfo WSA Expected magnitude limit of frameSet in this in J 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.

jExpRms dxsVariability, udsVariability WSA Rms calculated from polynomial fit to minimum RMS as a function of magnitude in J band real 4 mag -0.9999995e9

The photometry is calculated for good observations in the best aperture. The mean, rms, median and median absolute deviation are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.

jGausig dxsJKsource, dxsSource, dxsSourceRemeasurement, gcsPointSource, gcsSource, gcsSourceRemeasurement, gcsZYJHKsource, gpsJHKsource, gpsPointSource, gpsSource, gpsSourceRemeasurement, reliableDxsSource, reliableGcsPointSource, reliableGpsPointSource, reliableUdsSource, udsSource, udsSourceRemeasurement WSA RMS of axes of ellipse fit in J real 4 pixels -0.9999995e9 MORPH_PARAM

jHallMag dxsJKsource, dxsSource, gcsPointSource, gcsSource, gcsZYJHKsource, reliableDxsSource, reliableGcsPointSource WSA Total point source J mag real 4 mag -0.9999995e9 PHOT_MAG

jHallMag reliableUdsSource, udsSource WSA Not available in SE output real 4 mag -0.9999995e9 PHOT_MAG

jHallMagErr dxsJKsource, dxsSource, gcsPointSource, gcsSource, gcsZYJHKsource, reliableDxsSource, reliableGcsPointSource WSA Error in total point source J mag real 4 mag -0.9999995e9 ERROR

jHallMagErr reliableUdsSource, udsSource WSA Not available in SE output real 4 mag -0.9999995e9 ERROR

jIntRms dxsVariability, udsVariability WSA Intrinsic rms in J-band real 4 mag -0.9999995e9

The photometry is calculated for good observations in the best aperture. The mean, rms, median and median absolute deviation are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.

jitterID Multiframe WSA Serial number in this telescope jitter pattern {image primary HDU keyword: JITTER_I} smallint 2 -9999 ID_NUMBER

jitterID Multiframe WSATransit Serial number in this telescope jitter pattern {image primary HDU keyword: JITTER_I} smallint 2 -9999 ID_NUMBER

jitterX Multiframe WSA X (RA) offset in tel jitter pattern {image primary HDU keyword: JITTER_X} real 4 arcsec -0.9999995e9 POS_EQ_RA_OFF

jitterX Multiframe WSATransit X (RA) offset in tel jitter pattern {image primary HDU keyword: JITTER_X} real 4 arcsec -0.9999995e9 POS_EQ_RA_OFF

jitterY Multiframe WSA Y (Dec) offset in tel jitter pattern {image primary HDU keyword: JITTER_Y} real 4 arcsec -0.9999995e9 POS_EQ_DEC_OFF

jitterY Multiframe WSATransit Y (Dec) offset in tel jitter pattern {image primary HDU keyword: JITTER_Y} real 4 arcsec -0.9999995e9 POS_EQ_DEC_OFF

jMag dxsSourceRemeasurement, gcsSourceRemeasurement, gpsSourceRemeasurement, udsSourceRemeasurement WSA J mag (as appropriate for this merged source) real 4 mag -0.9999995e9 PHOT_MAG

jMag ukirtFSstars WSA J band total magnitude on the MKO(UFTI) system real 4 mag PHOT_INT-MAG

jMagErr dxsSourceRemeasurement, gcsSourceRemeasurement, gpsSourceRemeasurement, udsSourceRemeasurement WSA Error in J mag real 4 mag -0.9999995e9 ERROR

jMagErr ukirtFSstars WSA J band magnitude error real 4 mag ERROR

jMagMAD dxsVariability, udsVariability WSA Median Absolute Deviation of J magnitude real 4 mag -0.9999995e9

The photometry is calculated for good observations in the best aperture. The mean, rms, median and median absolute deviation are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.

jMagRms dxsVariability, udsVariability WSA rms of J magnitude real 4 mag -0.9999995e9

The photometry is calculated for good observations in the best aperture. The mean, rms, median and median absolute deviation are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.

jmaxCadence dxsVariability, udsVariability WSA 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.

jmeanMag dxsVariability, udsVariability WSA Mean J magnitude real 4 mag -0.9999995e9

The photometry is calculated for good observations in the best aperture. The mean, rms, median and median absolute deviation are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.

jmedCadence dxsVariability, udsVariability WSA 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.

jmedianMag dxsVariability, udsVariability WSA Median J magnitude real 4 mag -0.9999995e9

The photometry is calculated for good observations in the best aperture. The mean, rms, median and median absolute deviation are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.

jmfID dxsJKmergeLog, gpsJHKmergeLog WSA the UID of the relevant multiframe bigint 8 ID_FRAME

jmfID dxsMergeLog, gcsMergeLog, gcsZYJHKmergeLog, gpsMergeLog, udsMergeLog WSA the UID of the relevant J multiframe bigint 8 ID_FRAME

jmh dxsSourceRemeasurement, gcsSourceRemeasurement, gpsSourceRemeasurement, lasSourceRemeasurement, udsSourceRemeasurement WSA Default colour J-H (using appropriate mags) real 4 mag PHOT_COLOR

jmhErr dxsSourceRemeasurement, gcsSourceRemeasurement, gpsSourceRemeasurement, lasSourceRemeasurement, udsSourceRemeasurement WSA Error on colour J-H real 4 mag ERROR

jmhExt dxsJKsource, gcsPointSource, gcsZYJHKsource, reliableDxsSource, reliableGcsPointSource, reliableUdsSource WSA Extended source colour J-H (using aperMag3) real 4 mag -0.9999995e9 PHOT_COLOR

jmhExt dxsSource, gcsSource, udsSource WSA Extended source colour J-H (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.

jmhExtErr dxsJKsource, gcsPointSource, gcsZYJHKsource, reliableDxsSource, reliableGcsPointSource, reliableUdsSource WSA Error on extended source colour J-H real 4 mag -0.9999995e9 ERROR

jmhExtErr dxsSource, gcsSource, udsSource WSA Error on extended source colour J-H 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.

jmhPnt dxsJKsource, gcsPointSource, gcsZYJHKsource, gpsJHKsource, gpsPointSource, reliableDxsSource, reliableGcsPointSource, reliableGpsPointSource, reliableUdsSource WSA Point source colour J-H (using aperMag3) real 4 mag -0.9999995e9 PHOT_COLOR

jmhPnt dxsSource, gcsSource, gpsSource, udsSource WSA Point source colour J-H (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.

jmhPntErr dxsJKsource, gcsPointSource, gcsZYJHKsource, gpsJHKsource, gpsPointSource, reliableDxsSource, reliableGcsPointSource, reliableGpsPointSource, reliableUdsSource WSA Error on point source colour J-H real 4 mag -0.9999995e9 ERROR

jmhPntErr dxsSource, gcsSource, gpsSource, udsSource WSA Error on point source colour J-H 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.

jminCadence dxsVariability, udsVariability WSA 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.

jmkExt dxsJKsource, reliableDxsSource, reliableUdsSource WSA Extended source colour J-K (using aperMag3) real 4 mag -0.9999995e9 PHOT_COLOR

jmkExt dxsSource, udsSource WSA Extended source colour J-K (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.

jmkExtErr dxsJKsource, reliableDxsSource, reliableUdsSource WSA Error on extended source colour J-K real 4 mag -0.9999995e9 ERROR

jmkExtErr dxsSource, udsSource WSA Error on extended source colour J-K 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.

jmkPnt dxsJKsource, reliableDxsSource, reliableUdsSource WSA Point source colour J-K (using aperMag3) real 4 mag -0.9999995e9 PHOT_COLOR

jmkPnt dxsSource, udsSource WSA Point source colour J-K (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.

jmkPntErr dxsJKsource, reliableDxsSource, reliableUdsSource WSA Error on point source colour J-K real 4 mag -0.9999995e9 ERROR

jmkPntErr dxsSource, udsSource WSA Error on point source colour J-K 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.

jnDof dxsVarFrameSetInfo, udsVarFrameSetInfo WSA Number of degrees of freedom of photometric fit in J band. smallint 2 -9999

The best fit solution to the expected RMS for all objects in the frameset. Objects were binned in ranges of magnitude and the median RMS (after clipping out variable objects using the median-absolute deviation) was calculated. The Strateva function $\zeta(m)>=a+b\,10^{0.4m}+c\,10^{0.8m}$ was fit, where $\zeta(m)$ is the expected RMS as a function of magnitude. The chi-squared and number of degrees of freedom are also calculated. This technique was used in Sesar et al. 2007, AJ, 134, 2236.

jndof dxsVariability, udsVariability WSA Number of degrees of freedom for chisquare int 4 -9999

The photometry is calculated for good observations in the best aperture. The mean, rms, median and median absolute deviation are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.

jnFlaggedObs dxsVariability WSA Number of detections in J band flagged as potentially spurious by dxsDetection.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.

jnFlaggedObs udsVariability WSA Number of detections in J band flagged as potentially spurious by udsDetection.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.

jnGoodObs dxsVariability, udsVariability WSA Number of good detections in J 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.

jnMissingObs dxsVariability, udsVariability WSA Number of J 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.

jObjID dxsJKsource, gcsPointSource, gcsZYJHKsource, gpsJHKsource, gpsPointSource, reliableDxsSource, reliableGcsPointSource, reliableGpsPointSource, reliableUdsSource WSA DEPRECATED (do not use) bigint 8 -99999999 ID_NUMBER

jObjID dxsSource, dxsSourceRemeasurement, gcsSource, gcsSourceRemeasurement, gpsSource, gpsSourceRemeasurement, udsSource, udsSourceRemeasurement WSA DEPRECATED (do not use) bigint 8 -99999999 ID_NUMBER

This attribute is included in source tables for historical reasons, but it's use is not recommended unless you really know what you are doing. In general, if you need to look up detection table attributes for a source in a given passband that are not in the source table, you should make an SQL join between source, mergelog and detection using the primary key attribute frameSetID and combination multiframeID, extNum, seqNum to associate related rows between the three tables. See the Q&A example SQL for more information.

joinCriterion RequiredNeighbours WSA the join criterion (search radius for matches) real 4 arcminutes ??

joinCriterion RequiredNeighbours WSATransit the join criterion (search radius for matches) real 4 arcminutes ??

jPA dxsJKsource, dxsSource, dxsSourceRemeasurement, gcsPointSource, gcsSource, gcsSourceRemeasurement, gcsZYJHKsource, gpsJHKsource, gpsPointSource, gpsSource, gpsSourceRemeasurement, reliableDxsSource, reliableGcsPointSource, reliableGpsPointSource, reliableUdsSource, udsSource, udsSourceRemeasurement WSA ellipse fit celestial orientation in J real 4 Degrees -0.9999995e9 POS_POS-ANG

jPetroMag dxsJKsource, dxsSource, gcsPointSource, gcsSource, gcsZYJHKsource, reliableDxsSource, reliableGcsPointSource, reliableUdsSource, udsSource WSA Extended source J mag (Petrosian) real 4 mag -0.9999995e9 PHOT_MAG

jPetroMagErr dxsJKsource, dxsSource, gcsPointSource, gcsSource, gcsZYJHKsource, reliableDxsSource, reliableGcsPointSource, reliableUdsSource, udsSource WSA Error in extended source J mag (Petrosian) real 4 mag -0.9999995e9 ERROR

jppErrBits dxsJKsource, dxsSourceRemeasurement, gcsPointSource, gcsSourceRemeasurement, gcsZYJHKsource, gpsJHKsource, gpsPointSource, gpsSource, gpsSourceRemeasurement, reliableDxsSource, reliableGcsPointSource, reliableGpsPointSource, reliableUdsSource, udsSource, udsSourceRemeasurement WSA additional WFAU post-processing error bits in J int 4 0 CODE_MISC

jppErrBits dxsSource, gcsSource WSA additional WFAU post-processing error bits in J int 4 0 CODE_MISC

Post-processing error quality bit flags assigned (NB: from UKIDSS DR2 release onwards) in the WSA curation procedure for survey data. From least to most significant byte in the 4-byte integer attribute byte 0 (bits 0 to 7) corresponds to information on generally innocuous conditions that are nonetheless potentially significant as regards the integrity of that detection; byte 1 (bits 8 to 15) corresponds to warnings; byte 2 (bits 16 to 23) corresponds to important warnings; and finally byte 3 (bits 24 to 31) corresponds to severe warnings:

Byte Bit Detection quality issue Threshold or bit mask Applies to

Decimal Hexadecimal

0 4 Deblended 16 0x00000010 LAS, GCS, GPS, DXS

0 6 Bad pixel(s) in default aperture 64 0x00000040 LAS, GCS, GPS, DXS

2 16 Close to saturated 65536 0x00010000 LAS, GCS, GPS

2 19 Possible crosstalk artefact/contamination 524288 0x00080000 LAS, GCS, DXS

2 22 Lies within a dither offset of the stacked frame boundary 4194304 0x00400000 LAS, GCS, GPS, DXS

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.

jprobVar dxsVariability, udsVariability WSA Probability of variable from chi-square (and other data) real 4 0.9999995e9

The photometry is calculated for good observations in the best aperture. The mean, rms, median and median absolute deviation are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.

jPsfMag dxsJKsource, dxsSource, gcsPointSource, gcsSource, gcsZYJHKsource, reliableDxsSource, reliableGcsPointSource WSA Point source profile-fitted J mag real 4 mag -0.9999995e9 PHOT_MAG

jPsfMag reliableUdsSource, udsSource WSA Not available in SE output real 4 mag -0.9999995e9 PHOT_MAG

jPsfMagErr dxsJKsource, dxsSource, gcsPointSource, gcsSource, gcsZYJHKsource, reliableDxsSource, reliableGcsPointSource WSA Error in point source profile-fitted J mag real 4 mag -0.9999995e9 ERROR

jPsfMagErr reliableUdsSource, udsSource WSA Not available in SE output real 4 mag -0.9999995e9 ERROR

jSeqNum dxsJKsource, dxsSource, gcsPointSource, gcsSource, gcsZYJHKsource, gpsJHKsource, gpsPointSource, gpsSource, reliableDxsSource, reliableGcsPointSource, reliableGpsPointSource, reliableUdsSource, udsSource WSA the running number of the J detection int 4 -99999999 ID_NUMBER

jSeqNum dxsSourceRemeasurement, gcsSourceRemeasurement, gpsSourceRemeasurement, udsSourceRemeasurement WSA the running number of the J remeasurement int 4 -99999999 ID_NUMBER

jSerMag2D dxsJKsource, dxsSource, gcsPointSource, gcsSource, gcsZYJHKsource, reliableDxsSource, reliableGcsPointSource WSA Extended source J mag (profile-fitted) real 4 mag -0.9999995e9 PHOT_MAG

jSerMag2D reliableUdsSource, udsSource WSA Not available in SE output real 4 mag -0.9999995e9 PHOT_MAG

jSerMag2DErr dxsJKsource, dxsSource, gcsPointSource, gcsSource, gcsZYJHKsource, reliableDxsSource, reliableGcsPointSource WSA Error in extended source J mag (profile-fitted) real 4 mag -0.9999995e9 ERROR

jSerMag2DErr reliableUdsSource, udsSource WSA Not available in SE output real 4 mag -0.9999995e9 ERROR

jskewness dxsVariability, udsVariability WSA Skewness in J 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 and median absolute deviation are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.

jtotalPeriod dxsVariability, udsVariability WSA total period of observations (last obs-first obs) real 4 days -0.9999995e9

The observations are classified as good, flagged or missing. Flagged observations are ones where the object has a ppErrBit flag. Missing observations are observations of the part of the sky that include the position of the object, but had no detection. All the statistics are calculated from good observations. The cadence parameters give the minimum, median and maximum time between observations, which is useful to know if the data could be used to find a particular type of variable.

julianDayNum Multiframe WSA the Julian Day number of the UKIRT night int 4 Julian days TIME_DATE

julianDayNum Multiframe WSATransit the Julian Day number of the UKIRT night int 4 Julian days TIME_DATE

julianDayNum MultiframeDetector WSA the Julian Day number of the UKIRT night {image primary HDU keyword: UTDATE} int 4 Julian days TIME_DATE

julianDayNum MultiframeDetector WSATransit the Julian Day number of the UKIRT night {image primary HDU keyword: UTDATE} int 4 Julian days TIME_DATE

junkSource JunkDetection SSA Source of junk: 1=satellite track; 2=diffraction spike; 3=bright stellar halo tinyint 1 CLASS_CODE

jVarClass dxsVariability, udsVariability WSA Classification of variability in this band smallint 2 -9999

The photometry is calculated for good observations in the best aperture. The mean, rms, median and median absolute deviation are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.

jXi dxsJKsource, gcsPointSource, gcsZYJHKsource, gpsJHKsource, gpsPointSource, reliableDxsSource, reliableGcsPointSource, reliableGpsPointSource, reliableUdsSource WSA Offset of J detection from master position (+east/-west) real 4 arcsec -0.9999995e9 POS_EQ_RA_OFF

jXi dxsSource, gcsSource, gpsSource, udsSource WSA Offset of J 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; also non-survey programmes) or 1.0 (UKIDSS GPS, DXS and UDS) arcseconds is used, the higher value enabling pairing of moving sources when epoch separations may be several years. Such a large association criterion can of course lead to spurious pairings in the merged sources lists (although note that between passband pairs, handshake pairing is done: both passbands must agree that the candidate pair is their nearest neighbour for the pair to propagate through into the merged source table). In order to help filter spurious pairings out, and assuming that large positional offsets between the different passband detections are not expected (e.g. because of source motion, or larger than usual positional uncertainties) then the attributes Xi and Eta can be used to filter any pairings with suspiciously large offsets in one or more bands. For example, for a clean sample of QSOs from the LAS, you might wish to insist that the offsets in the selected sample are all below 1 arcsecond: simply add WHERE clauses into the SQL sample selection script to exclude all Xi and Eta values larger than the threshold you want.

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30/04/2009