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Glossary of WSA NonSurvey attributes (UKIDSSDR10)

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

B

NameSchema TableDatabaseDescriptionTypeLengthUnitDefault ValueUnified Content Descriptor
b [nspid]CurrentAstrometry, [nspid]PreviousAstrometry WSA NonSurvey Galactic latitude of device centre float 8 Degrees   pos.galactic.lat
b [nspid]Detection, [nspid]Source, [nspid]SynopticSource WSA NonSurvey Galactic latitude float 8 Degrees   POS_GAL_LAT
bandMergingCriterion [nspid]Programme WSA NonSurvey maximum timespan over which different filters are merged into sources in the synoptic source table. real 4 minutes -0.9999995e9  
beamNS [nspid]Multiframe WSA NonSurvey Topend: N-S beam {image primary HDU keyword: NSBEAM} real 4   -0.9999995e9  
beamWE [nspid]Multiframe WSA NonSurvey Topend: W-E beam {image primary HDU keyword: WEBEAM} real 4   -0.9999995e9  
bitsPerPix [nspid]MultiframeDetector WSA NonSurvey Number of bits per data pixel, eg. +32 = 4 byte integers {image extension keyword: BITPIX} smallint 2 FITS bitpix   meta.number
bMag [nspid]FSstars WSA NonSurvey B band total magnitude real 4 mag -0.9999995e9 PHOT_INT-MAG
brAperMag3 [nspid]Source WSA NonSurvey Default point/extended source Br aperture corrected mag (2.0 arcsec aperture diameter)
If in doubt use this flux estimator
real 4 mag -0.9999995e9 PHOT_MAG
brAperMag3Err [nspid]Source WSA NonSurvey Error in default point/extended source Br mag (2.0 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR
brAperMag4 [nspid]Source WSA NonSurvey Extended source Br aperture corrected mag (2.8 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG
brAperMag4Err [nspid]Source WSA NonSurvey Error in extended source Br mag (2.8 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR
brAperMag6 [nspid]Source WSA NonSurvey Extended source Br aperture corrected mag (5.7 arcsec aperture diameter) real 4 mag -0.9999995e9 PHOT_MAG
brAperMag6Err [nspid]Source WSA NonSurvey Error in extended source Br mag (5.7 arcsec aperture diameter) real 4 mag -0.9999995e9 ERROR
brClass [nspid]Source WSA NonSurvey discrete image classification flag in Br smallint 2   -9999 CLASS_MISC
brClassStat [nspid]Source WSA NonSurvey N(0,1) stellarness-of-profile statistic in Br real 4   -0.9999995e9 STAT_PROP
brDeblend [nspid]Source WSA NonSurvey placeholder flag indicating parent/child relation in Br 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.
brEll [nspid]Source WSA NonSurvey 1-b/a, where a/b=semi-major/minor axes in Br real 4   -0.9999995e9 PHYS_ELLIPTICITY
breNum [nspid]MergeLog WSA NonSurvey the extension number of this Br frame tinyint 1     NUMBER
brErrBits [nspid]Source WSA NonSurvey processing warning/error bitwise flags in Br 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.
brEta [nspid]Source WSA NonSurvey Offset of Br 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; UHS; 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. NB: the master position is the position of the detection in the shortest passband in the set, rather than the ra/dec of the source as stored in source attributes of the same name. The former is used in the pairing process, while the latter is generally the optimally weighted mean position from an astrometric solution or other combinatorial process of all individual detection positions across the available passbands.
brGausig [nspid]Source WSA NonSurvey RMS of axes of ellipse fit in Br real 4 pixels -0.9999995e9 MORPH_PARAM
brHallMag [nspid]Source WSA NonSurvey Total point source Br mag real 4 mag -0.9999995e9 PHOT_MAG
brHallMagErr [nspid]Source WSA NonSurvey Error in total point source Br mag real 4 mag -0.9999995e9 ERROR
brmfID [nspid]MergeLog WSA NonSurvey the UID of the relevant Br multiframe bigint 8     ID_FRAME
brmkExt [nspid]Source WSA NonSurvey Extended source colour Br-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.
brmkExtErr [nspid]Source WSA NonSurvey Error on extended source colour Br-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.
brmkPnt [nspid]Source WSA NonSurvey Point source colour Br-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.
brmkPntErr [nspid]Source WSA NonSurvey Error on point source colour Br-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.
brPA [nspid]Source WSA NonSurvey ellipse fit celestial orientation in Br real 4 Degrees -0.9999995e9 POS_POS-ANG
brPetroMag [nspid]Source WSA NonSurvey Extended source Br mag (Petrosian) real 4 mag -0.9999995e9 PHOT_MAG
brPetroMagErr [nspid]Source WSA NonSurvey Error in extended source Br mag (Petrosian) real 4 mag -0.9999995e9 ERROR
brppErrBits [nspid]Source WSA NonSurvey additional WFAU post-processing error bits in Br 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:
ByteBitDetection quality issue Threshold or bit mask Applies to
DecimalHexadecimal
0 4 Deblended 16 0x00000010 All VDFS catalogues
0 6 Bad pixel(s) in default aperture 64 0x00000040 All VDFS catalogues
1 15 Source in poor flat field region 32768 0x00008000 All but mosaics
2 16 Close to saturated 65536 0x00010000 All VDFS catalogues (though deeps excluded prior to DR8)
2 17 Photometric calibration probably subject to systematic error 131072 0x00020000 GPS only
2 19 Possible crosstalk artefact/contamination 524288 0x00080000 All but GPS
2 22 Lies within a dither offset of the stacked frame boundary 4194304 0x00400000 All but mosaics

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.
brPsfMag [nspid]Source WSA NonSurvey Point source profile-fitted Br mag real 4 mag -0.9999995e9 PHOT_MAG
brPsfMagErr [nspid]Source WSA NonSurvey Error in point source profile-fitted Br mag real 4 mag -0.9999995e9 ERROR
brSeqNum [nspid]Source WSA NonSurvey the running number of the Br detection int 4   -99999999 ID_NUMBER
brSerMag2D [nspid]Source WSA NonSurvey Extended source Br mag (profile-fitted) real 4 mag -0.9999995e9 PHOT_MAG
brSerMag2DErr [nspid]Source WSA NonSurvey Error in extended source Br mag (profile-fitted) real 4 mag -0.9999995e9 ERROR
brXi [nspid]Source WSA NonSurvey Offset of Br 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; UHS; 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. NB: the master position is the position of the detection in the shortest passband in the set, rather than the ra/dec of the source as stored in source attributes of the same name. The former is used in the pairing process, while the latter is generally the optimally weighted mean position from an astrometric solution or other combinatorial process of all individual detection positions across the available passbands.



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07/11/2017