{"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":"2026-09-02T00:16:20.405Z","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-54-b","name":"Kepler-54 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":886.1701398201691,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":294.7739245,"dec_deg":43.0561976,"epoch_ra_deg":294.990185,"epoch_dec_deg":43.11699,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"Kepler-54","semi_major_axis_km":9260108.196329998,"periapsis_km":null,"mass_kg":5.852724510435552e+24,"mass_msun":0.00000294342,"constellation":"Cygnus","discovered":"2012","featured":false,"url":"https://spacecatalog.org/object/kepler-54-b","radius_km":13394.010000000002,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"Kepler-54","host_v_mag":16.282,"eccentricity":0.022,"uncertainties":{"mass_kg":[1.3138769309141034e+24,2.0305370750490692e+24],"distance_ly":[9.515612319885989,9.515612319885989],"eccentricity":[0.015,0.02],"semi_major_axis_km":[368010.761922,368010.761922],"orbital_period_days":[0.000069,0.000069]},"host_mass_solar":0.51,"inclination_deg":89.59,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":0.5,"planets_in_system":3,"discovery_facility":"Kepler","host_spectral_type":"M1 V","host_temperature_k":3705,"orbital_period_days":8.0109434,"transit_midpoint_bjd":2455003.20573,"equilibrium_temperature_k":453},"designations":[{"catalog":"Exoplanet","designation":"Kepler-54 b"}],"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."}