{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.672","julian_year":2026.672,"time":"2026-09-03T09:46:58.956Z","years_from_j2000":26.672,"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-51-d","name":"Kepler-51 d","class":"gas_giant","category":"exoplanet","object_type":"Gas giant","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":2556.5147970209273,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":296.4797624,"dec_deg":49.9376486,"epoch_ra_deg":296.663418,"epoch_dec_deg":50.002463,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"Kepler-51","semi_major_axis_km":76145316.1863,"periapsis_km":null,"mass_kg":4.538847579521448e+25,"mass_msun":0.0000228265,"constellation":"Cygnus","discovered":"2014","featured":false,"url":"https://spacecatalog.org/object/kepler-51-d","radius_km":61867.57,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"Kepler-51","host_v_mag":14.885,"eccentricity":0.008,"uncertainties":{"mass_kg":[6.569384654570517e+24,6.569384654570517e+24],"radius_km":[3189.05,3189.05],"distance_ly":[43.111350006599146,44.58231527010166],"eccentricity":[0.008,0.011],"host_mass_solar":[0.12,0.12],"inclination_deg":[0.08,0.06],"host_radius_solar":[0.5,0.5],"host_temperature_k":[107,107],"semi_major_axis_km":[2991957.414,2991957.414],"orbital_period_days":[0.002,0.005],"argument_of_periastron_deg":[50.6,68.2]},"host_mass_solar":1.04,"inclination_deg":89.91,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":0.94,"planets_in_system":4,"discovery_facility":"Kepler","host_temperature_k":6018,"orbital_period_days":130.194,"transit_midpoint_bjd":2455695.9323,"equilibrium_temperature_k":381,"argument_of_periastron_deg":-12.6},"designations":[{"catalog":"Exoplanet","designation":"Kepler-51 d"}],"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."}