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Glossary of WSA attributes
This Glossary alphabetically lists all attributes used in the UKIDSSDR4 database(s) held in the WSA. If you would like to have more information about the schema tables please use the UKIDSSDR4 Schema Browser (other Browser versions).

A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

P

Q

R

S

T

U

V

W

X

Y

Z

Z
Name	Schema Table	Database	Description	Type	Length	Unit	Default Value	Unified Content Descriptor
z11	Multiframe	WSA	Spherical: Z11 {image primary HDU keyword: Z11}	real	4		-0.9999995e9
z11	Multiframe	WSATransit	Spherical: Z11 {image primary HDU keyword: Z11}	real	4		-0.9999995e9
z7	Multiframe	WSA	Coma: Z7 {image primary HDU keyword: Z7}	real	4		-0.9999995e9
z7	Multiframe	WSATransit	Coma: Z7 {image primary HDU keyword: Z7}	real	4		-0.9999995e9
z8	Multiframe	WSA	Coma: Z8 {image primary HDU keyword: Z8}	real	4		-0.9999995e9
z8	Multiframe	WSATransit	Coma: Z8 {image primary HDU keyword: Z8}	real	4		-0.9999995e9
zAperMag3	gcsPointSource, gcsZYJHKsource, reliableGcsPointSource	WSA	Default point/extended source Z aperture corrected mag (2.0 arcsec aperture diameter)	real	4	mag	-0.9999995e9	PHOT_MAG
zAperMag3	gcsSource	WSA	Default point/extended source Z aperture corrected mag (2.0 arcsec aperture diameter) If in doubt use this flux estimator	real	4	mag	-0.9999995e9	PHOT_MAG
zAperMag3Err	gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource	WSA	Error in default point/extended source Z mag (2.0 arcsec aperture diameter)	real	4	mag	-0.9999995e9	ERROR
zAperMag4	gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource	WSA	Extended source Z aperture corrected mag (2.8 arcsec aperture diameter)	real	4	mag	-0.9999995e9	PHOT_MAG
zAperMag4Err	gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource	WSA	Error in extended source Z mag (2.8 arcsec aperture diameter)	real	4	mag	-0.9999995e9	ERROR
zAperMag6	gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource	WSA	Extended source Z aperture corrected mag (5.7 arcsec aperture diameter)	real	4	mag	-0.9999995e9	PHOT_MAG
zAperMag6Err	gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource	WSA	Error in extended source Z mag (5.7 arcsec aperture diameter)	real	4	mag	-0.9999995e9	ERROR
zClass	gcsPointSource, gcsSource, gcsSourceRemeasurement, gcsZYJHKsource, reliableGcsPointSource	WSA	discrete image classification flag in Z	smallint	2		-9999	CLASS_MISC
zClassStat	gcsPointSource, gcsSource, gcsSourceRemeasurement, gcsZYJHKsource, reliableGcsPointSource	WSA	N(0,1) stellarness-of-profile statistic in Z	real	4		-0.9999995e9	STAT_PROP
zd	twomass_scn	2MASS	Scan's distance from the zenith at beginning of scan.	real	4	degrees		POS_ZD_RES
zDeblend	gcsPointSource, gcsSourceRemeasurement, gcsZYJHKsource, reliableGcsPointSource	WSA	placeholder flag indicating parent/child relation in Z	int	4		-99999999	CODE_MISC
zDeblend	gcsSource	WSA	placeholder flag indicating parent/child relation in Z	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.
zEll	gcsPointSource, gcsSource, gcsSourceRemeasurement, gcsZYJHKsource, reliableGcsPointSource	WSA	1-b/a, where a/b=semi-major/minor axes in Z	real	4		-0.9999995e9	PHYS_ELLIPTICITY
zeNum	gcsMergeLog	WSA	the extension number of this Z frame	tinyint	1			NUMBER
zeNum	gcsZYJHKmergeLog	WSA	the extension number of this frame	tinyint	1			NUMBER
zErrBits	gcsPointSource, gcsSourceRemeasurement, gcsZYJHKsource, reliableGcsPointSource	WSA	processing warning/error bitwise flags in Z	int	4		-99999999	CODE_MISC
zErrBits	gcsSource	WSA	processing warning/error bitwise flags in Z	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.
zEta	gcsPointSource, gcsZYJHKsource, reliableGcsPointSource	WSA	Offset of Z detection from master position (+north/-south)	real	4	arcsec	-0.9999995e9	POS_EQ_DEC_OFF
zEta	gcsSource	WSA	Offset of Z detection from master position (+north/-south)	real	4	arcsec	-0.9999995e9	POS_EQ_DEC_OFF
			When associating individual passband detections into merged sources, a generous (in terms of the positional uncertainties) pairing radius of 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.
zGausig	gcsPointSource, gcsSource, gcsSourceRemeasurement, gcsZYJHKsource, reliableGcsPointSource	WSA	RMS of axes of ellipse fit in Z	real	4	pixels	-0.9999995e9	MORPH_PARAM
zHallMag	gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource	WSA	Total point source Z mag	real	4	mag	-0.9999995e9	PHOT_MAG
zHallMagErr	gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource	WSA	Error in total point source Z mag	real	4	mag	-0.9999995e9	ERROR
zMag	gcsSourceRemeasurement	WSA	Z mag (as appropriate for this merged source)	real	4	mag	-0.9999995e9	PHOT_MAG
zMagErr	gcsSourceRemeasurement	WSA	Error in Z mag	real	4	mag	-0.9999995e9	ERROR
zmfID	gcsMergeLog	WSA	the UID of the relevant Z multiframe	bigint	8			ID_FRAME
zmfID	gcsZYJHKmergeLog	WSA	the UID of the relevant multiframe	bigint	8			ID_FRAME
zmy	gcsSourceRemeasurement	WSA	Default colour Z-Y (using appropriate mags)	real	4	mag		PHOT_COLOR
zmyErr	gcsSourceRemeasurement	WSA	Error on colour Z-Y	real	4	mag		ERROR
zmyExt	gcsPointSource, gcsZYJHKsource, reliableGcsPointSource	WSA	Extended source colour Z-Y (using aperMag3)	real	4	mag	-0.9999995e9	PHOT_COLOR
zmyExt	gcsSource	WSA	Extended source colour Z-Y (using aperMag3)	real	4	mag	-0.9999995e9	PHOT_COLOR
			Default colours from pairs of adjacent passbands within a given set (e.g. Y-J, J-H and H-K for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the point-source colours and extended source colours are computed from the aperture corrected AperMag3 fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands) and generally good signal-to-noise. At some point in the future, this may be changed such that point-source colours will be computed from the PSF-fitted measures and extended source colours computed from the 2-d Sersic model profile fits.
zmyExtErr	gcsPointSource, gcsZYJHKsource, reliableGcsPointSource	WSA	Error on extended source colour Z-Y	real	4	mag	-0.9999995e9	ERROR
zmyExtErr	gcsSource	WSA	Error on extended source colour Z-Y	real	4	mag	-0.9999995e9	ERROR
			Default colours from pairs of adjacent passbands within a given set (e.g. Y-J, J-H and H-K for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the point-source colours and extended source colours are computed from the aperture corrected AperMag3 fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands) and generally good signal-to-noise. At some point in the future, this may be changed such that point-source colours will be computed from the PSF-fitted measures and extended source colours computed from the 2-d Sersic model profile fits.
zmyPnt	gcsPointSource, gcsZYJHKsource, reliableGcsPointSource	WSA	Point source colour Z-Y (using aperMag3)	real	4	mag	-0.9999995e9	PHOT_COLOR
zmyPnt	gcsSource	WSA	Point source colour Z-Y (using aperMag3)	real	4	mag	-0.9999995e9	PHOT_COLOR
			Default colours from pairs of adjacent passbands within a given set (e.g. Y-J, J-H and H-K for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the point-source colours and extended source colours are computed from the aperture corrected AperMag3 fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands) and generally good signal-to-noise. At some point in the future, this may be changed such that point-source colours will be computed from the PSF-fitted measures and extended source colours computed from the 2-d Sersic model profile fits.
zmyPntErr	gcsPointSource, gcsZYJHKsource, reliableGcsPointSource	WSA	Error on point source colour Z-Y	real	4	mag	-0.9999995e9	ERROR
zmyPntErr	gcsSource	WSA	Error on point source colour Z-Y	real	4	mag	-0.9999995e9	ERROR
			Default colours from pairs of adjacent passbands within a given set (e.g. Y-J, J-H and H-K for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the point-source colours and extended source colours are computed from the aperture corrected AperMag3 fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands) and generally good signal-to-noise. At some point in the future, this may be changed such that point-source colours will be computed from the PSF-fitted measures and extended source colours computed from the 2-d Sersic model profile fits.
zObjID	gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource	WSA	the UID of the Z detection	bigint	8		-99999999	ID_NUMBER
zObjID	gcsSourceRemeasurement	WSA	the UID of the Z remeasurement	bigint	8		-99999999	ID_NUMBER
zone	ExternalSurveyTable	WSA	default (0) or special (n) zone	smallint	2			ID_REGION
zone	ExternalSurveyTable	WSATransit	default (0) or special (n) zone	smallint	2			ID_REGION
zPA	gcsPointSource, gcsSource, gcsSourceRemeasurement, gcsZYJHKsource, reliableGcsPointSource	WSA	ellipse fit celestial orientation in Z	real	4	Degrees	-0.9999995e9	POS_POS-ANG
zPetroMag	gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource	WSA	Extended source Z mag (Petrosian)	real	4	mag	-0.9999995e9	PHOT_MAG
zPetroMagErr	gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource	WSA	Error in extended source Z mag (Petrosian)	real	4	mag	-0.9999995e9	ERROR
zppErrBits	gcsPointSource, gcsSourceRemeasurement, gcsZYJHKsource, reliableGcsPointSource	WSA	additional WFAU post-processing error bits in Z	int	4		0	CODE_MISC
zppErrBits	gcsSource	WSA	additional WFAU post-processing error bits in Z	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.
zPsfMag	gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource	WSA	Point source profile-fitted Z mag	real	4	mag	-0.9999995e9	PHOT_MAG
zPsfMagErr	gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource	WSA	Error in point source profile-fitted Z mag	real	4	mag	-0.9999995e9	ERROR
zSeqNum	gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource	WSA	the running number of the Z detection	int	4		-99999999	ID_NUMBER
zSeqNum	gcsSourceRemeasurement	WSA	the running number of the Z remeasurement	int	4		-99999999	ID_NUMBER
zSerMag2D	gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource	WSA	Extended source Z mag (profile-fitted)	real	4	mag	-0.9999995e9	PHOT_MAG
zSerMag2DErr	gcsPointSource, gcsSource, gcsZYJHKsource, reliableGcsPointSource	WSA	Error in extended source Z mag (profile-fitted)	real	4	mag	-0.9999995e9	ERROR
ZSOURCE	mgcBrightSpec	MGC	Identifier for best redshift and quality	varchar	10
zXi	gcsPointSource, gcsZYJHKsource, reliableGcsPointSource	WSA	Offset of Z detection from master position (+east/-west)	real	4	arcsec	-0.9999995e9	POS_EQ_RA_OFF
zXi	gcsSource	WSA	Offset of Z detection from master position (+east/-west)	real	4	arcsec	-0.9999995e9	POS_EQ_RA_OFF
			When associating individual passband detections into merged sources, a generous (in terms of the positional uncertainties) pairing radius of 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.