WFCAM Science Archive

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

Y

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

y calDetection, commDetection, dxsDetection, dxsListRemeasurement, gcsDetection, gcsListRemeasurement, gpsDetection, gpsListRemeasurement, lasDetection, lasListRemeasurement, udsDetection, udsListRemeasurement WSA Y coordinate of detection {catalogue TType keyword: Y_coordinate}
Intensity-weighted isophotal centre-of-gravity in Y. real 4 pixels POS_PLATE_Y

y_coadd twomass_xsc 2MASS y (in-scan) position (coadd coord.). real 4 arcsec INST_POS

yAperMag3 calSourceEpochs, calSourceMeans, commSource, gcsSource, lasSource WSA Extended source Y mag (2.0 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG

yAperMag3Err calSourceEpochs, calSourceMeans, commSource, gcsSource, lasSource WSA Error in extended source Y mag (2.0 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR

yAperMag4 calSourceEpochs, calSourceMeans, commSource, gcsSource, lasSource WSA Extended source Y mag (2.8 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG

yAperMag4Err calSourceEpochs, calSourceMeans, commSource, gcsSource, lasSource WSA Error in extended source Y mag (2.8 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR

yAperMag6 calSourceEpochs, calSourceMeans, commSource, gcsSource, lasSource WSA Extended source Y mag (5.7 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG

yAperMag6Err calSourceEpochs, calSourceMeans, commSource, gcsSource, lasSource WSA Error in extended source Y mag (5.7 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR

yCen Detection SSA Intensity-weighted Y-centroid of image float 8 microns POS_PLATE_Y

yClass calSourceEpochs, commSource, gcsSource, gcsSourceRemeasurement, lasSource, lasSourceRemeasurement WSA discrete image classification flag in Y smallint 2 -9999 CLASS_MISC

yClassStat calSourceEpochs, commSource, gcsSource, gcsSourceRemeasurement, lasSource, lasSourceRemeasurement WSA N(0,1) stellarness-of-profile statistic in Y real 4 -0.9999995e9 STAT_PROP

yDeblend calSourceEpochs, commSource, gcsSource, gcsSourceRemeasurement, lasSource, lasSourceRemeasurement WSA flag indicating parent/child relation in Y int 4 -99999999 CODE_MISC

yEll calSourceEpochs, commSource, gcsSource, gcsSourceRemeasurement, lasSource, lasSourceRemeasurement WSA 1-b/a, where a/b=semi-major/minor axes in Y real 4 -0.9999995e9 PHYS_ELLIPTICITY

yeNum calMergeLogEpochs, commMergeLog, gcsMergeLog, lasMergeLog WSA the extension number of this Y detector tinyint 1 NUMBER

yErr calDetection, commDetection, dxsDetection, dxsListRemeasurement, gcsDetection, gcsListRemeasurement, gpsDetection, gpsListRemeasurement, lasDetection, lasListRemeasurement, udsDetection, udsListRemeasurement WSA Error in Y coordinate {catalogue TType keyword: Y_coordinate_err}
Estimate of centroid error. real 4 pixels ERROR

yErrBits calSourceEpochs, commSource, gcsSource, gcsSourceRemeasurement, lasSource, lasSourceRemeasurement WSA processing warning/error bitwise flags in Y int 4 -99999999 CODE_MISC

yEta calSourceEpochs, commSource, gcsSource, lasSource WSA Offset of Y detection from master position (+north/-south) real 4 arcsec -0.9999995e9 POS_EQ_DEC_OFF

When associating individual passband detections into merged sources, a generous (in terms of the positional uncertainties) pairing radius of 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.

yGausig calSourceEpochs, commSource, gcsSource, gcsSourceRemeasurement, lasSource, lasSourceRemeasurement WSA RMS of axes of ellipse fit in Y real 4 pixels -0.9999995e9 MORPH_PARAM

yHallMag calSourceEpochs, calSourceMeans, commSource, gcsSource, lasSource WSA Point source Y mag real 4 mag -0.9999995e9 PHOT_MAG

yHallMagErr calSourceEpochs, calSourceMeans, commSource, gcsSource, lasSource WSA Error in point source Y mag real 4 mag -0.9999995e9 ERROR

yMag CurrentStdStarInfo, PreviousStdStarInfo WSA Y band total magnitude of star (from external sources if primary) real 4 mag PHOT_INT-MAG

yMag gcsSourceRemeasurement, lasSourceRemeasurement WSA Y mag (as appropriate for this merged source) real 4 mag -0.9999995e9 PHOT_MAG

yMagErr CurrentStdStarInfo, PreviousStdStarInfo WSA Y band magnitude error of star real 4 mag ERROR

yMagErr gcsSourceRemeasurement, lasSourceRemeasurement WSA Error in Y mag real 4 mag -0.9999995e9 ERROR

ymax Detection SSA Topmost extent of image on plate float 8 microns POS_PLATE_Y

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

ymin Detection SSA Bottommost extent of image on plate float 8 microns POS_PLATE_Y

ymj gcsSourceRemeasurement, lasSourceRemeasurement WSA Default colour Y-J (using appropriate mags) real 4 mag PHOT_COLOR

ymj_1Ext lasSource WSA Extended source colour Y-J 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 are computed from the seeing-matched aperture measure (the "Hall" magnitude) while the extended source colours are computed from the fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands). 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.

ymj_1ExtErr lasSource WSA Error on extended source colour Y-J 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 are computed from the seeing-matched aperture measure (the "Hall" magnitude) while the extended source colours are computed from the fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands). 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.

ymj_1Pnt lasSource WSA Point source colour Y-J 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 are computed from the seeing-matched aperture measure (the "Hall" magnitude) while the extended source colours are computed from the fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands). 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.

ymj_1PntErr lasSource WSA Error on point source colour Y-J 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 are computed from the seeing-matched aperture measure (the "Hall" magnitude) while the extended source colours are computed from the fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands). 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.

ymjErr gcsSourceRemeasurement, lasSourceRemeasurement WSA Error on colour Y-J real 4 mag ERROR

ymjExt calSourceEpochs, calSourceMeans, commSource, gcsSource WSA Extended source colour Y-J (using appropriate mags) 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 are computed from the seeing-matched aperture measure (the "Hall" magnitude) while the extended source colours are computed from the fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands). 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.

ymjExtErr calSourceEpochs, calSourceMeans, commSource, gcsSource WSA Error on colour Y-J 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 are computed from the seeing-matched aperture measure (the "Hall" magnitude) while the extended source colours are computed from the fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands). 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.

ymjPnt calSourceEpochs, calSourceMeans, commSource, gcsSource WSA Point source colour Y-J (using appropriate mags) 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 are computed from the seeing-matched aperture measure (the "Hall" magnitude) while the extended source colours are computed from the fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands). 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.

ymjPntErr calSourceEpochs, calSourceMeans, commSource, gcsSource WSA Error on colour Y-J 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 are computed from the seeing-matched aperture measure (the "Hall" magnitude) while the extended source colours are computed from the fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands). 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.

yObjID calSourceEpochs, commSource, gcsSource, lasSource WSA the UID of the Y detection bigint 8 -99999999 ID_NUMBER

yObjID gcsSourceRemeasurement, lasSourceRemeasurement WSA the UID of the Y remeasurement bigint 8 -99999999 ID_NUMBER

yPA calSourceEpochs, commSource, gcsSource, gcsSourceRemeasurement, lasSource, lasSourceRemeasurement WSA ellipse fit celestial orientation in Y real 4 Degrees -0.9999995e9 POS_POS-ANG

yPetroMag calSourceEpochs, calSourceMeans, commSource, gcsSource, lasSource WSA Extended source Y mag (Petrosian) real 4 mag -0.9999995e9 PHOT_MAG

yPetroMagErr calSourceEpochs, calSourceMeans, commSource, gcsSource, lasSource WSA Error in extended source Y mag (Petrosian) real 4 mag -0.9999995e9 ERROR

yPixSize CurrentAstrometry WSA Angular size of pixels in Y real 4 Arcseconds -0.9999995e9 POS_ANG_DIST_GENERAL

yPixSize PreviousAstrometry WSA Angular size of pixels in Y real 4 Arcseconds POS_ANG_DIST_GENERAL

yPnt Plate SSA Centre of scan area in Y real 4 microns POS_PLATE_Y

yppErrBits calSourceEpochs, commSource, gcsSource, gcsSourceRemeasurement, lasSource, lasSourceRemeasurement WSA additional WFAU post-processing error bits in Y int 4 -99999999 CODE_MISC

yPsfMag calSourceEpochs, calSourceMeans, commSource, gcsSource, lasSource WSA Point source profile-fitted Y mag real 4 mag -0.9999995e9 PHOT_MAG

yPsfMagErr calSourceEpochs, calSourceMeans, commSource, gcsSource, lasSource WSA Error in point source profile-fitted Y mag real 4 mag -0.9999995e9 ERROR

ySeqNum calSourceEpochs, commSource, gcsSource, lasSource WSA the running number of the Y detection int 4 -99999999 ID_NUMBER

ySeqNum gcsSourceRemeasurement, lasSourceRemeasurement WSA the running number of the Y remeasurement int 4 -99999999 ID_NUMBER

ySerMag2D calSourceEpochs, calSourceMeans, commSource, gcsSource, lasSource WSA Extended source Y mag (profile-fitted) real 4 mag -0.9999995e9 PHOT_MAG

ySerMag2DErr calSourceEpochs, calSourceMeans, commSource, gcsSource, lasSource WSA Error in extended source Y mag (profile-fitted) real 4 mag -0.9999995e9 ERROR

ySize MultiframeDetector WSA Y-axis size of image {catalogue extension keyword: NYOUT} int 4 -99999999 NUMBER

yXi calSourceEpochs, commSource, gcsSource, lasSource WSA Offset of Y detection from master position (+east/-west) real 4 arcsec -0.9999995e9 POS_EQ_RA_OFF

When associating individual passband detections into merged sources, a generous (in terms of the positional uncertainties) pairing radius of 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.

WFAU, Institute for Astronomy,
Royal Observatory, Blackford Hill
Edinburgh, EH9 3HJ, UK
Tel +44 131 668 8356 (office)
or +44 131 668 8100 (switchboard)

wsa-support@roe.ac.uk
27/01/2009