WFCAM Science Archive

Glossary of WSA attributes

This Glossary alphabetically lists all attributes used in the UKIDSSDR1 database(s) held in the WSA. If you would like to have more information about the schema tables please use the UKIDSSDR1 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 dxsDetection, dxsListRemeasurement, gcsDetection, gcsListRemeasurement, gpsDetection, gpsListRemeasurement, lasDetection, lasListRemeasurement, 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 ptsDetection WSATransit Y coordinate of detection {catalogue TType keyword: Y_coordinate}
Intensity-weighted isophotal centre-of-gravity in Y. real 4 pixels POS_PLATE_Y

y udsDetection WSA Y coordinate of detection (SE: Y_IMAGE) {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 gcsSource, lasSource WSA Default point/extended source Y aperture corrected mag (2.0 arcsec aperture diameter)
If in doubt use this flux estimator real 4 mag -0.9999995e9 PHOT_MAG

yAperMag3Err gcsSource, lasSource WSA Error in default point/extended source Y mag (2.0 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR

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

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

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

yAperMag6Err 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 gcsSource, gcsSourceRemeasurement, lasSource, lasSourceRemeasurement WSA discrete image classification flag in Y smallint 2 -9999 CLASS_MISC

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

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

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

yeNum gcsMergeLog, lasMergeLog WSA the extension number of this Y frame tinyint 1 NUMBER

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

yErr ptsDetection WSATransit Error in Y coordinate {catalogue TType keyword: Y_coordinate_err}
Estimate of centroid error. real 4 pixels ERROR

yErr udsDetection WSA Error in Y coordinate (SE: ERRY2_IMAGE^½) {catalogue TType keyword: Y_coordinate_err}
Estimate of centroid error. real 4 pixels ERROR

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

yEta 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 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.

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

yHallMag gcsSource, lasSource WSA Total point source Y mag real 4 mag -0.9999995e9 PHOT_MAG

yHallMagErr gcsSource, lasSource WSA Error in total 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 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 (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.

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 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.

ymj_1Pnt lasSource WSA Point source colour Y-J (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.

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 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.

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

ymjExt gcsSource WSA Extended source colour Y-J (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.

ymjExtErr gcsSource 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 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.

ymjPnt gcsSource WSA Point source colour Y-J (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.

ymjPntErr gcsSource 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 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.

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

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

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

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

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

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

yppErrBits gcsSource, gcsSourceRemeasurement, lasSource, lasSourceRemeasurement WSA additional WFAU post-processing error bits in Y int 4 0 CODE_MISC

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

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

ySeqNum 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 gcsSource, lasSource WSA Extended source Y mag (profile-fitted) real 4 mag -0.9999995e9 PHOT_MAG

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

ySize MultiframeDetector WSA Corresponding image size (Y); value only available if catalogue file exists {catalogue extension keyword: NYOUT} int 4 -99999999 NUMBER

ySize MultiframeDetector WSATransit Corresponding image size (Y); value only available if catalogue file exists {catalogue extension keyword: NYOUT} int 4 -99999999 NUMBER

yXi 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 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.

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