{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.682","julian_year":2026.682,"time":"2026-09-07T00:09:08.361Z","years_from_j2000":26.682,"frame":"date","applied":"Proper motion, then precession and nutation. The catalogued J2000 position is carried along the great circle the object's own published motion puts it on, at a constant velocity, and the result is referred to the true equator and equinox of this instant. Those are separate things: the motion moves the object, and the rotation turns the grid under it by about fifty arcseconds a year, with nutation adding up to another seventeen.","excluded":"Parallax, the radial-velocity perspective term, aberration and refraction; each is below the accuracy of the catalogued positions themselves. An object with no published proper motion comes back where the catalogue has it rather than at a fabricated zero, and says so with a null pm_ra_mas_yr. A body with no fixed position is not propagated at all — its place comes from an ephemeris, which is what /api/v1/visible answers with."},"slug":"hd-20781-c","name":"HD 20781 c","class":"neptune_like_planet","category":"exoplanet","object_type":"Neptune-like planet","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":117.32334141037836,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":50.0139757,"dec_deg":-28.7841175,"epoch_ra_deg":50.296051,"epoch_dec_deg":-28.686523,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"HD 20781","semi_major_axis_km":15019626.218279999,"periapsis_km":null,"mass_kg":3.183165473532805e+25,"mass_msun":0.0000160086,"constellation":"Fornax","discovered":"2019","featured":false,"url":"https://spacecatalog.org/object/hd-20781-c","radius_km":13840.477,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"HD 20781","host_v_mag":8.48,"eccentricity":0.09,"uncertainties":{"mass_kg":[4.001352471420224e+24,4.1805175074539655e+24],"distance_ly":[0.17155825467900704,0.17188441105672378],"eccentricity":[0.06,0.09],"host_radius_solar":[0.022175,0.02391],"host_temperature_k":[29,29],"semi_major_axis_km":[762949.14057,688150.2052199999],"orbital_period_days":[0.0034,0.0033],"argument_of_periastron_deg":[70.21,53.87]},"host_mass_solar":0.7,"stars_in_system":2,"discovery_method":"Radial Velocity","host_radius_solar":0.833609,"planets_in_system":5,"discovery_facility":"La Silla Observatory","host_spectral_type":"K0 V","host_temperature_k":5256,"orbital_period_days":13.8905,"periastron_epoch_bjd":2455503.5204,"equilibrium_temperature_k":730.3,"argument_of_periastron_deg":7.44},"designations":[{"catalog":"Exoplanet","designation":"HD 20781 c"}],"source":{"id":"exoplanet_archive","name":"NASA Exoplanet Archive (Planetary Systems Composite Parameters)","url":"https://exoplanetarchive.ipac.caltech.edu/cgi-bin/TblView/nph-tblView?app=ExoTbls&config=PSCompPars","license":"Public domain (NASA)"},"updated_at":"2026-09-02T19:50:56.720Z","attribution":"Data from SpaceCatalog.org. Individual records carry their source and license in `source`; attribution is required for CC-BY and CC-BY-SA rows."}