{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.671","julian_year":2026.671,"time":"2026-09-03T00:32:38.685Z","years_from_j2000":26.671,"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-52-d","name":"Kepler-52 d","class":"super_earth","category":"exoplanet","object_type":"Super-Earth","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":1048.729740037971,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":286.7380152,"dec_deg":49.9757383,"epoch_ra_deg":286.910754,"epoch_dec_deg":50.016802,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"Kepler-52","semi_major_axis_km":27226812.467399996,"periapsis_km":null,"mass_kg":5.3079134966962826e+26,"mass_msun":0.000266943,"constellation":"Draco","discovered":"2014","featured":false,"url":"https://spacecatalog.org/object/kepler-52-d","radius_km":12437.295,"radius_kind":null,"data_quality":"The published mass and radius imply a density no material has. One of the two is likely an upper limit rather than a measurement.","description":null,"properties":{"host_star":"Kepler-52","host_v_mag":15.513,"eccentricity":0,"uncertainties":{"radius_km":[1339.401,1339.401],"distance_ly":[7.772306480989996,7.8929843407451905],"host_mass_solar":[0.014,0.014],"host_radius_solar":[0.021,0.021],"host_temperature_k":[100,100],"orbital_period_days":[0.000253,0.000253]},"host_mass_solar":0.577,"inclination_deg":89.98,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":0.556,"planets_in_system":3,"discovery_facility":"Kepler","host_spectral_type":"M0 V","host_temperature_k":4263,"orbital_period_days":36.445171,"transit_midpoint_bjd":2454984.60115,"equilibrium_temperature_k":332},"designations":[{"catalog":"Exoplanet","designation":"Kepler-52 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."}