{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.667","julian_year":2026.667,"time":"2026-09-01T12:13:32.418Z","years_from_j2000":26.667,"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":"kepler-520-c","name":"Kepler-520 c","class":"terrestrial_planet","category":"exoplanet","object_type":"Terrestrial planet","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":2034.8929021385393,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":293.1802903,"dec_deg":41.6177408,"epoch_ra_deg":293.401377,"epoch_dec_deg":41.674711,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"Kepler-520","semi_major_axis_km":9028231.496745,"periapsis_km":null,"mass_kg":7.40548815606131e+24,"mass_msun":0.00000372433,"constellation":"Cygnus","discovered":"2016","featured":false,"url":"https://spacecatalog.org/object/kepler-520-c","radius_km":6824.567000000001,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"Kepler-520","host_v_mag":12.798,"eccentricity":0,"uncertainties":{"radius_km":[318.90500000000003,446.46700000000004],"host_mass_solar":[0.043,0.036],"host_radius_solar":[0.05,0.054],"host_temperature_k":[60.87,68.96],"semi_major_axis_km":[119678.29656,119678.29656],"orbital_period_days":[0.00001231,0.00001231]},"host_mass_solar":1.1,"inclination_deg":83.02,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":1.09,"planets_in_system":2,"discovery_facility":"Kepler","host_temperature_k":6112,"orbital_period_days":5.21104261,"transit_midpoint_bjd":2454964.53958,"equilibrium_temperature_k":1107},"designations":[{"catalog":"Exoplanet","designation":"Kepler-520 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":"2026-08-30T09:56:50.739Z","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."}