Sub-selection of reliable, BUT INCOMPLETE, stellar objects from Source. |
This view of table Source defines a reliable, but incomplete, selection
of point sources. The select statement of the view requires the source to be present on at least three out of four plates (Nplates > 2) along with a "good" astrometric fit (ie. chi-squared value < 3.0) and on each plate the following conditions are placed on available morphological parameters: ellipticity < 0.25 (ie. image elongation is less than 33%); blend = 0 (ie. image has not been deblended); -3.0 < profile statistic < 3.0 (ie. the areal profile set of the source is close to an idealised PSF set in terms of a 3sigma limit on the N(0,1) profile statistic); quality flag < 128 (ie. any sign of a possibly bad image rejects that image from the view); and limits to exclude the most crowded areas near the Galactic plane and bulge. The use of this, or any other, SSA view depends on the particular science application. If your science application needs a reliable selection of stellar objects but does NOT require high completeness levels, then use this view. Completeness of ReliableStars will be poor in low Galactic latitude regions in particular; note that the Galactic plane region -10 < b < +10 and Galactic bulge region within 20 degrees of the Galactic Centre are not included in this view. If high levels of completeness are required, then use the CompleteStars view. |
select *
from Source
where chi2 < 3.0 and
Nplates > 2 and
ellipB < 0.25 and blendB < 1 and qualB < 128 and
((prfstatB > -3.0 and prfstatB < +3.0) or prfstatB < -0.9e9) and
ellipR1 < 0.25 and blendR1 < 1 and qualR1 < 128 and
((prfstatR1 > -3.0 and prfstatR1 < +3.0) or prfstatR1 < -0.9e9) and
ellipR2 < 0.25 and blendR2 < 1 and qualR2 < 128 and
((prfstatR2 > -3.0 and prfstatR2 < +3.0) or prfstatR2 < -0.9e9) and
ellipI < 0.25 and blendI < 1 and qualI < 128 and
((prfstatI > -3.0 and prfstatI < +3.0) or prfstatI < -0.9e9) and
(b > +10.0 or b < -10.0) and d > +20.0
High completeness sub-selection of stellar objects from Source. |
This view of table Source defines a highly complete selection of point
sources. The select statement of the view requires the source to be present on at least two out of four plates (Nplates > 1) along with an adequate astrometric fit (ie. chi-squared value < 5.0) and on each plate the following conditions are placed on available morphological parameters: ellipticity < 0.33 (ie. image elongation is less than 50%); -3.0 < profile statistic < 4.5 (ie. the areal profile set of the source is close to an idealised PSF set in terms of a 3sigma lower limit and +4.5 upper limit on the N(0,1) profile statistic); quality flag < 2048 (ie. strong warnings concerning quality issues reject sources from the view). The use of this, or any other, SSA view depends on the particular science application. If your science application needs a high completeness selection of stellar objects but can cope with some contamination (particularly misclassified sources, poorly parameterised deblends at the faint end and poorly parameterised/calibrated images in very crowded regions) then use this view. |
select *
from Source
where chi2 < 5.0 and
Nplates > 1 and
ellipB < 0.3333333 and qualB < 2048 and
((prfstatB > -3.0 and prfstatB < +4.5) or prfstatB < -0.9e9) and
ellipR1 < 0.3333333 and qualR1 < 2048 and
((prfstatR1 > -3.0 and prfstatR1 < +4.5) or prfstatR1 < -0.9e9) and
ellipR2 < 0.3333333 and qualR2 < 2048 and
((prfstatR2 > -3.0 and prfstatR2 < +4.5) or prfstatR2 < -0.9e9) and
ellipI < 0.3333333 and qualI < 2048 and
((prfstatI > -3.0 and prfstatI < +4.5) or prfstatI < -0.9e9)
High reliability sub-selection of galaxies from Source. |
This view of table Source defines a reliable selection of extended
objects (ie. galaxies) from Source. Reliable in this context means that each galaxy must appear on the UKJ, UKR and UKI plates; must be classed as non-stellar on UKJ & UKR; must not be deblended on UKJ or UKR; and must have good quality UKJ, UKR & UKI (ie. quality < 128). A magnitude cut of Bj < 20.0 provides a reliability of better than approximately 90%. The use of this, or any other, SSA view depends on the particular science application. If your science application needs a highly reliable selection of galaxies, then use this view. But be aware that this selection is not in any sense complete, particularly at faint magnitudes. Note also that because the SSA has general poor completeness of extragalactic objects at low Galactic latitudes and severe contamination by blended stars which are indistinguishable from extended sources, this view is currently limited to |b| > 35.0 and Galactic Centre distance d > 45.0 (to avoid the crowded Bulge region). |
select *
from Source
where objidB > 0 and objidR2 > 0 and objidI > 0 and
classB = 1 and classR2 = 1 and
blendB = 0 and blendR2 = 0 and
qualB < 128 and qualR2 < 128 and qualI < 128 and
gcormagB < 20.0 and
d > 45.0 and (b > +35.0 or b < -35.0)
This view of table Source defines a more complete selection of extended
objects (ie. galaxies) from Source than does the ReliableGalaxies view. Each galaxy must appear on the UKJ and UKR plates; must be classed as non-stellar on UKJ & UKR; and must have good quality UKJ and UKR (ie. quality < 128). No magnitude cut on this view yields much better completeness than ReliableGalaxies but at the expense of increase contamination by stellar objects, poorly deblended objects and spurious sources. The use of this, or any other, SSA view depends on the particular science application. If your science application needs a more complete selection of galaxies than is provided by the ReliableGalaxies view, then use this view. Please note that the SSA will have general poor completeness of extragalactic objects at low Galactic latitudes. |
--as select *
--from Source
--where objidB > 0 and objidR2 > 0 and
-- classB = 1 and classR2 = 1 and
-- qualB < 128 and qualR2 < 128
--go