The input and output astrometry parameters with associated error and correlation information are each represented by a 22-element array, with the following elements:
index gaia_source name unit description ----- ---------------- ---- ----------- 0: ra deg right ascension 1: dec deg declination 2: parallax mas parallax 3: pmra mas/yr proper motion in RA * cos(dec) 4: pmdec mas/yr proper motion in Declination 5: radial_velocity km/s barycentric radial velocity 6: ra_error mas error in right ascension 7: dec_error mas error in declination 8: parallax_error mas error in parallax 9: pmra_error mas/yr error in RA proper motion * cos(dec) 10: pmdec_error mas/yr error in Declination proper motion 11: radial_velocity_error km/s error in barycentric radial velocity 12: ra_dec_corr correlation between ra and dec 13: ra_parallax_corr correlation between ra and parallax 14: ra_pmra_corr correlation between ra and pmra 15: ra_pmdec_corr correlation between ra and pmdec 16: dec_parallax_corr correlation between dec and parallax 17: dec_pmra_corr correlation between dec and pmra 18: dec_pmdec_corr correlation between dec and pmdec 19: parallax_pmra_corr correlation between parallax and pmra 20: parallax_pmdec_corr correlation between parallax and pmdec 21: pmra_pmdec_corr correlation between pmra and pmdecNote the correlation coefficients, always in the range -1..1, are dimensionless.
This is clearly an unwieldy function to invoke, but if you are using it with the gaia_source catalogue itself, or other similar catalogues with the same column names and units, you can invoke it by just copying and pasting the example shown in this documentation.
This transformation is only applicable for radial velocities determined independently of the astrometry, such as those obtained with a spectrometer. It is not applicable for the back-transformation of data already propagated to another epoch.
epochPropErr(-15.5, array(
ra,dec,parallax,pmra,pmdec,radial_velocity,
ra_error,dec_error,parallax_error,pmra_error,pmdec_error,radial_velocity_error,
ra_dec_corr,ra_parallax_corr,ra_pmra_corr,ra_pmdec_corr,
dec_parallax_corr,dec_pmra_corr,dec_pmdec_corr,
parallax_pmra_corr,parallax_pmdec_corr,
pmra_pmdec_corr))
- calculates the astrometry with all errors and correlations at
2000.0 for gaia_source values that were observed at 2015.5.