{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.670","julian_year":2026.67,"time":"2026-09-02T13:22:41.078Z","years_from_j2000":26.67,"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":"kapteyn-c","name":"Kapteyn 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":12.827893413788377,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":77.9586613,"dec_deg":-45.0430198,"epoch_ra_deg":78.156777,"epoch_dec_deg":-45.009835,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"Kapteyn","semi_major_axis_km":46524937.7877,"periapsis_km":null,"mass_kg":4.180517507453966e+25,"mass_msun":0.0000210244,"constellation":"Pictor","discovered":"2014","featured":false,"url":"https://spacecatalog.org/object/kapteyn-c","radius_km":16200.374000000002,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"Kapteyn","host_v_mag":8.86,"eccentricity":0.23,"uncertainties":{"mass_kg":[5.972167867791379e+24,7.166601441349655e+24],"distance_ly":[0.001337241148638648,0.001337241148638648],"eccentricity":[0.12,0.1],"host_mass_solar":[0.014,0.014],"host_radius_solar":[0.025,0.025],"host_temperature_k":[50,50],"semi_major_axis_km":[2094370.1897999998,5684719.086599999],"orbital_period_days":[0.25,0.25],"argument_of_periastron_deg":[33.2,28.9]},"host_mass_solar":0.281,"stars_in_system":1,"discovery_method":"Radial Velocity","host_radius_solar":0.291,"planets_in_system":1,"discovery_facility":"Multiple Observatories","host_spectral_type":"M2.0V","host_temperature_k":3550,"orbital_period_days":121.54,"equilibrium_temperature_k":165.59,"argument_of_periastron_deg":3.9},"designations":[{"catalog":"Exoplanet","designation":"Kapteyn c"},{"catalog":"Host star","designation":"Kapteyn"}],"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":"2026-09-01T22:58:55.274Z","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."}