Table information for 'alerce_tap.lsst_detection'

General

Table Description:

Individual LSST Difference Image Analysis sources, containing detailed measurements from difference imaging including PSF photometry, aperture photometry, trail and dipole fitting for moving objects, shape moments, forced photometry on science and template images, and extensive quality flags for pixels and measurements.

This table is available for ADQL queries and through the TAP endpoint.

Resource Description:

Multi-survey astronomical object catalog containing astrometric and statistical information from multiple surveys. This table provides aggregated properties for astronomical objects including position, detection statistics, and temporal coverage.

For a list of all services and tables belonging to this table's resource, see Information on resource 'ALeRCE Multi-Survey Object Catalog'

Citing this table

To cite the table as such, we suggest the following BibTeX entry:

@MISC{vo:alerce_tap_lsst_,
  year=2026,
  title={{LSST} {DIA} Source Detections},
  author={{ALeRCE} Team},
  url={http://tap.alerce.online/tableinfo/alerce_tap.lsst_detection},
  howpublished={{VO} resource provided by the {ALeRCE} {TAP} service}
}

Columns

Sorted alphabetically. [Sort by DB column index]

NameTable Head DescriptionUnitUCD
apflux Apflux Flux in a 12 pixel radius aperture on the difference image N/A phot.flux
apflux_flag Apflux_flag General aperture flux algorithm failure flag; set if anything went wrong when measuring aperture fluxes. Another apFlux flag field should also be set to provide more information N/A meta.code.qual
apflux_flag_aperturetruncated Apflux_flag_aperturetruncated Aperture did not fit within measurement image N/A meta.code.qual
apfluxerr Apfluxerr Estimated uncertainty of apFlux N/A stat.error;phot.flux
bboxsize Bboxsize Size of the square bounding box that fully contains the detection footprint pix phys.angSize
centroid_flag Centroid_flag General centroid algorithm failure flag; set if anything went wrong when fitting the centroid. Another centroid flag field should also be set to provide more information N/A meta.code.qual
created_date Created_date Date record was created N/A time.creation
decerr Decerr Uncertainty of dec deg stat.error;pos.eq.dec
detector Detector Detector number N/A instr.det
diaobjectid Diaobjectid Id of the diaObject this source was associated with, if any. If not, it is set to NULL (each diaSource will be associated with either a diaObject or ssObject) N/A meta.id
dipoleangle Dipoleangle Maximum likelihood fit of the angle between the meridian through the centroid and the dipole direction (bearing, from negative to positive lobe) deg pos.posAng
dipolechi2 Dipolechi2 Chi^2 statistic of the model fit N/A stat.fit.chi2
dipolefitattempted Dipolefitattempted Attempted to fit a dipole model to this source N/A meta.code
dipolefluxdiff Dipolefluxdiff Maximum likelihood value for the difference of absolute fluxes of the two lobes for a dipole model N/A phot.flux
dipolefluxdifferr Dipolefluxdifferr Uncertainty of dipoleFluxDiff N/A stat.error;phot.flux
dipolelength Dipolelength Maximum likelihood value for the lobe separation in dipole model arcsec phys.angSize
dipolemeanflux Dipolemeanflux Maximum likelihood value for the mean absolute flux of the two lobes for a dipole model N/A phot.flux
dipolemeanfluxerr Dipolemeanfluxerr Uncertainty of dipoleMeanFlux N/A stat.error;phot.flux
dipolendata Dipolendata The number of data points (pixels) used to fit the model N/A meta.number
extendedness Extendedness A measure of extendedness, computed by comparing an object's moment-based traced radius to the PSF moments. extendedness = 1 implies a high degree of confidence that the source is extended. extendedness = 0 implies a high degree of confidence that the source is point-like N/A src.class.starGalaxy
forced_psfflux_flag Forced_psfflux_flag Forced PSF photometry on science image failed. Another forced_PsfFlux flag field should also be set to provide more information N/A meta.code.qual
forced_psfflux_flag_edge Forced_psfflux_flag_edge Forced PSF flux on science image was too close to the edge of the image to use the full PSF model N/A meta.code.qual
forced_psfflux_flag_nogoodpixels Forced_psfflux_flag_nogoodpixels Forced PSF flux not enough non-rejected pixels in data to attempt the fit N/A meta.code.qual
glint_trail Glint_trail This flag is set if the source is part of a glint trail N/A meta.code
has_stamp Has_stamp Has image stamp flag N/A meta.code
isdipole Isdipole Source well fit by a dipole N/A meta.code
isnegative Isnegative Source was detected as significantly negative N/A meta.code
ixx Ixx Adaptive second moment of the source intensity nJy.arcsec**2 phys.size
ixxpsf Ixxpsf Adaptive second moment for the PSF nJy.arcsec**2 phys.size
ixy Ixy Adaptive second moment of the source intensity nJy.arcsec**2 phys.size
ixypsf Ixypsf Adaptive second moment for the PSF nJy.arcsec**2 phys.size
iyy Iyy Adaptive second moment of the source intensity nJy.arcsec**2 phys.size
iyypsf Iyypsf Adaptive second moment for the PSF nJy.arcsec**2 phys.size
measurement_id Measurement_id Unique identifier of this DiaSource N/A meta.id
oid Oid Object identifier N/A meta.id;src
parentdiasourceid Parentdiasourceid Id of the parent diaSource this diaSource has been deblended from, if any N/A meta.id
pixelflags Pixelflags General pixel flags failure; set if anything went wrong when setting pixels flags from this footprint's mask. This implies that some pixelFlags for this source may be incorrectly set to False N/A meta.code.qual
pixelflags_bad Pixelflags_bad Bad pixel in the DiaSource footprint N/A meta.code.qual
pixelflags_cr Pixelflags_cr Cosmic ray in the DiaSource footprint N/A meta.code.qual
pixelflags_crcenter Pixelflags_crcenter Cosmic ray in the 3x3 region around the centroid N/A meta.code.qual
pixelflags_edge Pixelflags_edge Some of the source footprint is outside usable exposure region (masked EDGE or centroid off image) N/A meta.code.qual
pixelflags_injected Pixelflags_injected Injection in the DiaSource footprint N/A meta.code.qual
pixelflags_injected_template Pixelflags_injected_template Template injection in the DiaSource footprint N/A meta.code.qual
pixelflags_injected_templatecenter Pixelflags_injected_templatecenter Template injection in the 3x3 region around the centroid N/A meta.code.qual
pixelflags_injectedcenter Pixelflags_injectedcenter Injection in the 3x3 region around the centroid N/A meta.code.qual
pixelflags_interpolated Pixelflags_interpolated Interpolated pixel in the DiaSource footprint N/A meta.code.qual
pixelflags_interpolatedcenter Pixelflags_interpolatedcenter Interpolated pixel in the 3x3 region around the centroid N/A meta.code.qual
pixelflags_nodata Pixelflags_nodata NO_DATA pixel in the source footprint N/A meta.code.qual
pixelflags_nodatacenter Pixelflags_nodatacenter NO_DATA pixel in the 3x3 region around the centroid N/A meta.code.qual
pixelflags_offimage Pixelflags_offimage DiaSource center is off image N/A meta.code.qual
pixelflags_saturated Pixelflags_saturated Saturated pixel in the DiaSource footprint N/A meta.code.qual
pixelflags_saturatedcenter Pixelflags_saturatedcenter Saturated pixel in the 3x3 region around the centroid N/A meta.code.qual
pixelflags_streak Pixelflags_streak Streak in the DiaSource footprint N/A meta.code.qual
pixelflags_streakcenter Pixelflags_streakcenter Streak in the 3x3 region around the centroid N/A meta.code.qual
pixelflags_suspect Pixelflags_suspect DiaSource's footprint includes suspect pixels N/A meta.code.qual
pixelflags_suspectcenter Pixelflags_suspectcenter Suspect pixel in the 3x3 region around the centroid N/A meta.code.qual
psfchi2 Psfchi2 Chi^2 statistic of the point source model fit N/A stat.fit.chi2
psfflux Psfflux Flux for Point Source model. Note this actually measures the flux difference between the template and the visit image N/A phot.flux
psfflux_flag Psfflux_flag Failure to derive linear least-squares fit of psf model. Another psfFlux flag field should also be set to provide more information N/A meta.code.qual
psfflux_flag_edge Psfflux_flag_edge Object was too close to the edge of the image to use the full PSF model N/A meta.code.qual
psfflux_flag_nogoodpixels Psfflux_flag_nogoodpixels Not enough non-rejected pixels in data to attempt the fit N/A meta.code.qual
psffluxerr Psffluxerr Uncertainty of psfFlux N/A stat.error;phot.flux
psflnl Psflnl Natural log likelihood of the observed data given the point source model N/A stat.likelihood
psfndata Psfndata The number of data points (pixels) used to fit the point source model N/A meta.number
ra_dec_cov Ra_dec_cov Covariance between ra and dec deg**2 stat.covariance;pos.eq
raerr Raerr Uncertainty of ra deg stat.error;pos.eq.ra
reliability Reliability Probability (0-1) that the diaSource is astrophysical, derived from a machine learning model N/A stat.probability
scienceflux Scienceflux Forced photometry flux for a point source model measured on the visit image centered at DiaSource position N/A phot.flux
sciencefluxerr Sciencefluxerr Estimated uncertainty of scienceFlux N/A stat.error;phot.flux
shape_flag Shape_flag General source shape algorithm failure flag; set if anything went wrong when measuring the shape. Another shape flag field should also be set to provide more information N/A meta.code.qual
shape_flag_no_pixels Shape_flag_no_pixels No pixels to measure shape N/A meta.code.qual
shape_flag_not_contained Shape_flag_not_contained Center not contained in footprint bounding box N/A meta.code.qual
shape_flag_parent_source Shape_flag_parent_source This source is a parent source; we should only be measuring on deblended children in difference imaging N/A meta.code.qual
sid Sid Survey identifier N/A meta.id
snr Snr The signal-to-noise ratio at which this source was detected in the difference image N/A stat.snr
ssobjectid Ssobjectid Id of the ssObject this source was associated with, if any. If not, it is set to NULL (each diaSource will be associated with either a diaObject or ssObject) N/A meta.id
templateflux Templateflux Forced photometry flux for a point source model measured on the template image centered at the DiaObject position N/A phot.flux
templatefluxerr Templatefluxerr Uncertainty of templateFlux N/A stat.error;phot.flux
timeprocessedmjdtai Timeprocessedmjdtai Time when the image was processed and this DiaSource record was generated, expressed as Modified Julian Date, International Atomic Time d time.processing
timewithdrawnmjdtai Timewithdrawnmjdtai Time when this record was marked invalid, expressed as Modified Julian Date, International Atomic Time d time.processing
trail_flag_edge Trail_flag_edge This flag is set if a trailed source extends onto or past edge pixels N/A meta.code.qual
trailangle Trailangle Maximum likelihood fit of the angle between the meridian through the centroid and the trail direction (bearing) deg pos.posAng
trailangleerr Trailangleerr Uncertainty of trailAngle deg stat.error
trailchi2 Trailchi2 Chi^2 statistic of the trailed source model fit N/A stat.fit.chi2
traildec Traildec Declination coordinate of centroid for trailed source model deg pos.eq.dec
traildecerr Traildecerr Uncertainty of trailDec deg stat.error;pos.eq.dec
trailflux Trailflux Flux for a trailed source model. Note this actually measures the flux difference between the template and the visit image N/A phot.flux
trailfluxerr Trailfluxerr Uncertainty of trailFlux N/A stat.error;phot.flux
traillength Traillength Maximum likelihood fit of trail length arcsec phys.angSize
traillengtherr Traillengtherr Uncertainty of trailLength arcsec stat.error
trailndata Trailndata The number of data points (pixels) used to fit the trailed source model N/A meta.number
trailra Trailra Right ascension coordinate of centroid for trailed source model deg pos.eq.ra
trailraerr Trailraerr Uncertainty of trailRa deg stat.error;pos.eq.ra
visit Visit Visit number N/A obs.field
x X x position computed by a centroiding algorithm pix pos.cartesian.x
xerr Xerr Uncertainty of x pix stat.error;pos.cartesian.x
y Y y position computed by a centroiding algorithm pix pos.cartesian.y
yerr Yerr Uncertainty of y pix stat.error;pos.cartesian.y

Columns that are parts of indices are marked like this.

VOResource

VO nerds may sometimes need VOResource XML for this table.