{"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":"2026-09-02T00:27:47.504Z","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-138-d","name":"Kepler-138 d","class":"super_earth","category":"exoplanet","object_type":"Super-Earth","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":218.07598189447984,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":290.3814122,"dec_deg":43.2930645,"epoch_ra_deg":290.59262,"epoch_dec_deg":43.343213,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"Kepler-138","semi_major_axis_km":19268205.746159997,"periapsis_km":null,"mass_kg":1.2541552522361896e+25,"mass_msun":0.00000630733,"constellation":"Lyra","discovered":"2014","featured":false,"url":"https://spacecatalog.org/object/kepler-138-d","radius_km":9630.931,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"Kepler-138","host_v_mag":13.04,"eccentricity":0.01,"uncertainties":{"mass_kg":[4.1805175074539655e+24,3.5833007206748275e+24],"radius_km":[255.12400000000002,255.12400000000002],"distance_ly":[0.34898732415691547,0.34898732415691547],"eccentricity":[0.005,0.005],"host_mass_solar":[0.012,0.012],"inclination_deg":[0.04,0.04],"host_radius_solar":[0.014,0.013],"host_temperature_k":[51,50],"semi_major_axis_km":[149597.8707,149597.8707],"orbital_period_days":[0.0006,0.0006],"argument_of_periastron_deg":[20,30]},"host_mass_solar":0.535,"inclination_deg":89.04,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":0.535,"planets_in_system":4,"discovery_facility":"Kepler","host_spectral_type":"M1 V","host_temperature_k":3841,"orbital_period_days":23.0923,"transit_midpoint_bjd":2454957.816,"equilibrium_temperature_k":345,"argument_of_periastron_deg":250},"designations":[{"catalog":"Exoplanet","designation":"Kepler-138 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":"2026-09-01T22:58:55.274Z","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."}