{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.668","julian_year":2026.668,"time":"2026-09-02T01:57:30.422Z","years_from_j2000":26.668,"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-221-d","name":"Kepler-221 d","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":1256.4554754419878,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":296.6547477,"dec_deg":46.8352242,"epoch_ra_deg":296.855172,"epoch_dec_deg":46.900449,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"Kepler-221","semi_major_axis_km":13015014.750899998,"periapsis_km":null,"mass_kg":2.155952600272688e+25,"mass_msun":0.0000108426,"constellation":"Cygnus","discovered":"2014","featured":false,"url":"https://spacecatalog.org/object/kepler-221-d","radius_km":17412.213,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"Kepler-221","host_v_mag":13.97,"eccentricity":0,"uncertainties":{"mass_kg":[4.837455972911017e+24,5.434672759690155e+24],"radius_km":[1594.525,1594.525],"distance_ly":[9.241640962603924,9.241640962603924],"host_mass_solar":[0.016,0.012],"host_radius_solar":[0.075,0.075],"host_temperature_k":[100,100],"orbital_period_days":[0.000011,0.000011]},"host_mass_solar":0.854,"inclination_deg":87.8,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":0.821,"planets_in_system":4,"discovery_facility":"Kepler","host_temperature_k":5243,"orbital_period_days":10.04156,"transit_midpoint_bjd":2454970.08456,"equilibrium_temperature_k":712},"designations":[{"catalog":"Exoplanet","designation":"Kepler-221 d"},{"catalog":"Host star","designation":"Kepler-221"}],"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."}