{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.670","julian_year":2026.67,"time":"2026-09-02T15:36:47.058Z","years_from_j2000":26.67,"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-540-b","name":"Kepler-540 b","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":1273.22969794796,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":290.6249953,"dec_deg":44.8737757,"epoch_ra_deg":290.828889,"epoch_dec_deg":44.924523,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"Kepler-540","semi_major_axis_km":87996459.503154,"periapsis_km":null,"mass_kg":4.658290936877275e+25,"mass_msun":0.0000234272,"constellation":"Cygnus","discovered":"2016","featured":false,"url":"https://spacecatalog.org/object/kepler-540-b","radius_km":17284.651,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"Kepler-540","host_v_mag":12.293,"eccentricity":0,"uncertainties":{"radius_km":[1658.306,2423.6780000000003],"distance_ly":[12.765760623833337,13.020162598452398],"host_mass_solar":[0.054,0.055],"host_radius_solar":[0.102,0.149],"host_temperature_k":[63.84,77.07],"semi_major_axis_km":[827276.224971,827276.224971],"orbital_period_days":[0.0005356,0.0005356]},"host_mass_solar":1.02,"inclination_deg":90,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":1.08,"planets_in_system":1,"discovery_facility":"Kepler","host_temperature_k":5946,"orbital_period_days":172.7049784,"transit_midpoint_bjd":2455069.92338,"equilibrium_temperature_k":355},"designations":[{"catalog":"Exoplanet","designation":"Kepler-540 b"},{"catalog":"Host star","designation":"Kepler-540"}],"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."}