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The starting point for the PS1 data archive is at Pan-STARRS1 data archive home page.


Description: Contains metadata for objects that have had their astrometry corrected using Gaia EDR3.  This table contains the original values from the ObjectThin table that have been updated, the replacement values that are in ObjectThin (highlighted in the comments), as well as additional information on the new astrometry. Reference: https://arxiv.org/abs/2206.09988.

Most users will simply use the updated values in ObjectThin; the values in this table may be useful for ongoing research projects that rely on details of the original PS1 DR2 positions.

NameUnitData TypeSizeDefault ValueDescription
objIDdimensionlessBIGINT8NAUnique object identifier used to join to ObjectThin.

mdra

degreesFLOAT8NAInitial Right ascension position (J2000) determined from weighted mean of Detection positions (before Gaia correction).
mddec
degreesFLOAT8NAInitial Declination position (J2000) determined from weighted mean of Detection positions (before Gaia correction).
mdmjd
daysFLOAT8NA

astrometry corrected replacement for epochMean in ObjectThin: Modified Julian Date (MJD) of the mean epoch corresponding to positions and proper motions.  This is the average of mdmjdra and mdmjddec.

mdmjdra
daysFLOAT8NAWeighted mean MJD for measurements that contributed to mdra.
mdmjddec
daysFLOAT8NAWeighted mean MJD for measurements that contributed to mddec.
nmd
dimensionlessINT4NANumber of detection measurements used.
mdraErr
milliarcsecondsFLOAT8NA

astrometry corrected replacement for raMeanErr in ObjectThin: Standard deviation in RA from weighted single epoch errors. Value is converted to arcsec in ObjectThin.

mddecErr
milliarcsecondsFLOAT8NAastrometry corrected replacement for raMeanErr in ObjectThin: Standard deviation in Dec from weighted single epoch errors. Value is converted to arcsec in ObjectThin.
mdpmra
milliarcseconds per yearFLOAT8NAProper motion in RA determined from weighted mean of Detection positions (before Gaia correction).
mdpmdec
milliarcseconds per yearFLOAT8NAProper motion in Dec determined from weighted mean of Detection positions (before Gaia correction).
mdpmraErr
milliarcseconds per yearFLOAT8NAnew column pmraErr in ObjectThin: Standard deviation in pmra from weighted single epoch errors.
mdpmdecErr
milliarcseconds per yearFLOAT8NAnew column pmdecErr in ObjectThin: Standard deviation in pmdec from weighted single epoch errors.
chisqra
dimensionlessFLOAT8NA

astrometry corrected replacement for posMeanChisq in ObjectThin = (chisqra+chisqdec)/2: Reduced chi-square in RA PM fit

chisqdec
dimensionlessFLOAT8NAastrometry corrected replacement for posMeanChisq in ObjectThin = (chisqra+chisqdec)/2: Reduced chi-square in Dec PM fit 
dcr
dimensionlessBIT1NADifferential chromatic refraction correction applied: 1=yes, 0=no
ra
degreesFLOAT8NAastrometry corrected replacement for raMean in ObjectThin: RA from single epoch detections (weighted mean) in equinox J2000 at the mean epoch given by epochMean after correction using Gaia EDR3 using the algorithm described in the paper.
dec
degreesFLOAT8NAastrometry corrected replacement for decMean in ObjectThin: Dec from single epoch detections (weighted mean) in equinox J2000 at the mean epoch given by epochMean after correction using Gaia EDR3 using the algorithm described in the paper.
pmra
milliarcseconds per yearFLOAT8NAnew column pmra in ObjectThin: Proper motion in RA from single epoch detections after correction using Gaia EDR3 using the algorithm described in the paper.
pmdec
milliarcseconds per yearFLOAT8NAnew column pmdec in ObjectThin: Proper motion in Dec from single epoch detections after correction using Gaia EDR3 using the algorithm described in the paper.
cxdimensionlessFLOAT8NAastrometry corrected replacement for cx in ObjectThin: Cartesian x on a unit sphere.
cydimensionlessFLOAT8NAastrometry corrected replacement for cy in ObjectThin: Cartesian y on a unit sphere.
czdimensionlessFLOAT8NAastrometry corrected replacement for cz in ObjectThin: Cartesian z on a unit sphere.
htmiddimensionlessBIGINT8NAastrometry corrected replacement for htmID in ObjectThin: Hierarchical triangular mesh (Szalay 2007) index.

Values for columns below are the original values from ObjectThin, copied before the astrometry update was applied.

NOTE: When querying this table, if these original column values are all NULL it indicates that the object (objid) does not exist in ObjectThin.  That applies mainly to objects south of declination -30 degrees.

raMeandegreesFLOAT8-999Right ascension from single epoch detections (weighted mean) in equinox J2000 at the mean epoch given by epochMean.
decMeandegreesFLOAT8-999Declination from single epoch detections (weighted mean) in equinox J2000 at the mean epoch given by epochMean.
raMeanErrarcsecREAL4-999Right ascension standard deviation from single epoch detections.
decMeanErrarcsecREAL4-999Declination standard deviation from single epoch detections.
epochMeandaysFLOAT8-999Modified Julian Date of the mean epoch corresponding to raMean, decMean (equinox J2000). Note that Gaia DR1 data is sometimes included in the mean position (see the FAQ for details); in those cases, the epochMean value is near the Gaia DR1 epoch 2015.5 = MJD 15023.  As a result, epochMean is not necessarily near the mean value of the PS1 measurement dates.  That is no longer true of the new astrometry-corrected value of epochMean – the new positions do not include any Gaia position or epoch information in the calculations except to calibrate local disortions in the PS1 coordinate system.
posMeanChisqdimensionlessREAL4-999Reduced chi squared value of mean position.
cxOrigdimensionlessFLOAT8NACartesian x on a unit sphere.
cyOrigdimensionlessFLOAT8NACartesian y on a unit sphere.
czOrigdimensionlessFLOAT8NACartesian z on a unit sphere.
htmIDOrigdimensionlessBIGINT8NAHierarchical triangular mesh (Szalay 2007) index.

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