LSST reference catalog schema description

The reference catalogs for use with LSST Data Management Science Pipelines have the following schema:

Catalog Schema

  • coord_ra: ICRS position of star on sky (an lsst.geom.Angle)
  • coord_dec: ICRS position of star on sky (an lsst.geom.Angle)
  • centroid: position of star on an exposure, if relevant (an lsst.afw.Point2D)
  • hasCentroid: is centroid usable? (a Flag)
  • <referenceFilterName>_flux: brightness in the specified reference catalog filter (nJy)
    Note: you can use astropy.units to convert from AB Magnitude to nJy: u.Magnitude(value, u.ABmag).to_value(u.nJy)
  • <referenceFilterName>_fluxErr (optional): brightness standard deviation (nJy); omitted if no data is available; possibly nan if data is available for some objects but not others
  • camFlux: brightness in default camera filter (nJy); omitted if defaultFilter not specified
  • camFluxErr: brightness standard deviation for default camera filter; omitted if defaultFilter not specified or standard deviation not available that filter
  • <cameraFilterName>_camFlux: brightness in specified camera filter (nJy)
  • <cameraFilterName>_camFluxErr (optional): brightness standard deviation in specified camera filter (nJy); omitted if no data is available;
    possibly nan if data is available for some objects but not others
  • photometric (optional): is the object usable for photometric calibration? (a Flag)
  • resolved (optional): is the object spatially resolved? (a Flag)
  • variable (optional): does the object have variable brightness? (a Flag)
  • coord_raErr: uncertainty in coord along the direction of right ascension (radian, an Angle) = uncertainty in ra * cos(dec); nan if unknown
  • coord_decErr: uncertainty in coord along the direction of declination (radian, an Angle);
    nan if unknown
The following are optional; fields should only be present if the information is available for at least some objects.

Numeric values are nan if unknown:

  • coord_ra_coord_dec_Cov: covariance between coord_ra and coord_dec (rad^2)
  • epoch: date of observation as TAI MJD (day)
  • pm_ra: proper motion along the direction of right ascension (rad/year, an Angle) = dra/dt * cos(dec)
  • pm_dec: proper motion along the direction of declination (rad/year, and Angle)
  • pm_raErr: uncertainty in pm_ra (rad/year)
  • pm_decErr: uncertainty in pm_dec (rad/year)
  • pm_ra_pm_dec_Cov: covariance between pm_ra and pm_dec (rad^2/year^2)
  • pm_flag: set if proper motion, error or covariance is bad
  • parallax: parallax (rad, an Angle)
  • parallaxErr: uncertainty in parallax (rad)
  • parallax_flag: set if parallax value or parallaxErr is bad
  • coord_ra_pm_ra_Cov: covariance between coord_ra and pm_ra (rad^2/year)
  • coord_ra_pm_dec_Cov: covariance between coord_ra and pm_dec (rad^2/year)
  • coord_ra_parallax_Cov: covariance between coord_ra and parallax (rad^2)
  • coord_dec_pm_ra_Cov: covariance between coord_dec and pm_ra (rad^2/year)
  • coord_dec_pm_dec_Cov: covariance between coord_dec and pm_dec (rad^2/year)
  • coord_dec_parallax_Cov: covariance between coord_dec and parallax (rad^2)
  • pm_ra_parallax_Cov: covariance between pm_ra and parallax (rad^2/year)
  • pm_dec_parallax_Cov: covariance between pm_dec and parallax (rad^2/year)