{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.665","julian_year":2026.665,"time":"2026-09-01T01:26:54.137Z","years_from_j2000":26.665,"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-4-b","name":"Kepler-4 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":1591.3691519004258,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":285.6154492,"dec_deg":50.1357712,"epoch_ra_deg":285.786257,"epoch_dec_deg":50.173984,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"Kepler-4","semi_major_axis_km":6821662.9039199995,"periapsis_km":null,"mass_kg":1.4615089206059064e+26,"mass_msun":0.0000735014,"constellation":"Draco","discovered":"2009","featured":false,"url":"https://spacecatalog.org/object/kepler-4-b","radius_km":25525.1562,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"Kepler-4","host_v_mag":12.285,"eccentricity":0,"uncertainties":{"mass_kg":[2.2777848247756322e+25,2.2777848247756322e+25],"radius_km":[1358.5353,1358.5353],"distance_ly":[18.78986892026159,19.236703157733526],"host_mass_solar":[0.091,0.053],"inclination_deg":[2.05,0.24],"host_radius_solar":[0.084,0.071],"host_temperature_k":[120,120],"semi_major_axis_km":[134638.08362999998,134638.08362999998],"orbital_period_days":[0.00022,0.00022]},"host_mass_solar":1.223,"inclination_deg":89.76,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":1.487,"planets_in_system":1,"discovery_facility":"Kepler","host_temperature_k":5857,"orbital_period_days":3.21346,"transit_midpoint_bjd":2454956.6127,"equilibrium_temperature_k":1650},"designations":[{"catalog":"Exoplanet","designation":"Kepler-4 b"},{"catalog":"Host star","designation":"Kepler-4"}],"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":"2026-08-30T09:56:50.739Z","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."}