{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.678","julian_year":2026.678,"time":"2026-09-05T12:45:40.595Z","years_from_j2000":26.678,"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-539-b","name":"Kepler-539 b","class":"gas_giant","category":"exoplanet","object_type":"Gas giant","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":1002.3372568715415,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":299.1224639,"dec_deg":41.8667953,"epoch_ra_deg":299.348526,"epoch_dec_deg":41.937832,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"Kepler-539","semi_major_axis_km":74619417.90516,"periapsis_km":null,"mass_kg":1.84119009001753e+27,"mass_msun":0.000925961,"constellation":"Cygnus","discovered":"2016","featured":false,"url":"https://spacecatalog.org/object/kepler-539-b","radius_km":53404.615806300004,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"Kepler-539","host_v_mag":12.444,"uncertainties":{"mass_kg":[5.504588928918389e+26,5.504588928918389e+26],"radius_km":[1215.3660893,1215.3660893],"distance_ly":[11.379596018537178,11.64378268448774],"host_mass_solar":[0.042,0.042],"inclination_deg":[0.086,0.086],"host_radius_solar":[0.018,0.018],"host_temperature_k":[80,80],"semi_major_axis_km":[1002305.7336899999,1002305.7336899999],"orbital_period_days":[0.00071,0.00071]},"host_mass_solar":1.048,"inclination_deg":89.845,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":0.952,"planets_in_system":2,"discovery_facility":"Kepler","host_spectral_type":"G2 V","host_temperature_k":5820,"orbital_period_days":125.63243,"transit_midpoint_bjd":2455588.871,"eccentricity_upper_limit":0.39,"equilibrium_temperature_k":387.6},"designations":[{"catalog":"Exoplanet","designation":"Kepler-539 b"},{"catalog":"Host star","designation":"Kepler-539"}],"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."}