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.
Name
Unit
Data Type
Size
Default Value
Description
objID
dimensionless
BIGINT
8
NA
Unique object identifier used to join to ObjectThin.
mdra
degrees
FLOAT
8
NA
Initial Right ascension position (J2000) determined from weighted mean of Detection positions (before Gaia correction).
mddec
degrees
FLOAT
8
NA
Initial Declination position (J2000) determined from weighted mean of Detection positions (before Gaia correction).
mdmjd
days
FLOAT
8
NA
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
days
FLOAT
8
NA
Weighted mean MJD for measurements that contributed to mdra.
mdmjddec
days
FLOAT
8
NA
Weighted mean MJD for measurements that contributed to mddec.
nmd
dimensionless
INT
4
NA
Number of detection measurements used.
mdraErr
milliarcseconds
FLOAT
8
NA
astrometry corrected replacement for raMeanErr in ObjectThin: Standard deviation in RA from weighted single epoch errors. Value is converted to arcsec in ObjectThin.
mddecErr
milliarcseconds
FLOAT
8
NA
astrometry 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 year
FLOAT
8
NA
Proper motion in RA determined from weighted mean of Detection positions (before Gaia correction).
mdpmdec
milliarcseconds per year
FLOAT
8
NA
Proper motion in Dec determined from weighted mean of Detection positions (before Gaia correction).
mdpmraErr
milliarcseconds per year
FLOAT
8
NA
new column pmraErr in ObjectThin: Standard deviation in pmra from weighted single epoch errors.
mdpmdecErr
milliarcseconds per year
FLOAT
8
NA
new column pmdecErr in ObjectThin: Standard deviation in pmdec from weighted single epoch errors.
chisqra
dimensionless
FLOAT
8
NA
astrometry corrected replacement for posMeanChisq in ObjectThin = (chisqra+chisqdec)/2: Reduced chi-square in RA PM fit
chisqdec
dimensionless
FLOAT
8
NA
astrometry corrected replacement for posMeanChisq in ObjectThin = (chisqra+chisqdec)/2: Reduced chi-square in Dec PM fit
astrometry 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
degrees
FLOAT
8
NA
astrometry 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 year
FLOAT
8
NA
new 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 year
FLOAT
8
NA
new column pmdec in ObjectThin: Proper motion in Dec from single epoch detections after correction using Gaia EDR3 using the algorithm described in the paper.
cx
dimensionless
FLOAT
8
NA
astrometry corrected replacement for cx in ObjectThin: Cartesian x on a unit sphere.
cy
dimensionless
FLOAT
8
NA
astrometry corrected replacement for cy in ObjectThin: Cartesian y on a unit sphere.
cz
dimensionless
FLOAT
8
NA
astrometry corrected replacement for cz in ObjectThin: Cartesian z on a unit sphere.
htmid
dimensionless
BIGINT
8
NA
astrometry 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.
raMean
degrees
FLOAT
8
-999
Right ascension from single epoch detections (weighted mean) in equinox J2000 at the mean epoch given by epochMean.
decMean
degrees
FLOAT
8
-999
Declination from single epoch detections (weighted mean) in equinox J2000 at the mean epoch given by epochMean.
raMeanErr
arcsec
REAL
4
-999
Right ascension standard deviation from single epoch detections.
decMeanErr
arcsec
REAL
4
-999
Declination standard deviation from single epoch detections.
epochMean
days
FLOAT
8
-999
Modified 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.