{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.674","julian_year":2026.674,"time":"2026-09-04T06:25:17.502Z","years_from_j2000":26.674,"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-553-c","name":"Kepler-553 c","class":"gas_giant","category":"exoplanet","object_type":"Gas giant","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":2376.130750760905,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":298.5508922,"dec_deg":48.3325405,"epoch_ra_deg":298.746135,"epoch_dec_deg":48.402209,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"Kepler-553","semi_major_axis_km":134338887.8886,"periapsis_km":null,"mass_kg":1.271743481837003e+28,"mass_msun":0.00639578,"constellation":"Cygnus","discovered":"2016","featured":false,"url":"https://spacecatalog.org/object/kepler-553-c","radius_km":73851.235776386,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"Kepler-553","host_v_mag":15.034,"eccentricity":0.346,"uncertainties":{"mass_kg":[8.161935778953899e+26,8.351748238929571e+26],"radius_km":[1787.300011012,2287.743978378],"distance_ly":[41.00111824277182,41.00111824277182],"eccentricity":[0.024,0.02],"host_mass_solar":[0.036,0.046],"inclination_deg":[0.0092,0.0054],"host_radius_solar":[0.021,0.026],"host_temperature_k":[78,76],"semi_major_axis_km":[1795174.4483999999,2243968.0604999997],"orbital_period_days":[0.0004,0.00039],"argument_of_periastron_deg":[3,3.6]},"host_mass_solar":0.889,"inclination_deg":89.8314,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":0.902,"planets_in_system":2,"discovery_facility":"Kepler","host_temperature_k":5191,"orbital_period_days":328.24017,"periastron_epoch_bjd":2454935.8,"transit_midpoint_bjd":2455032.1977,"equilibrium_temperature_k":251,"argument_of_periastron_deg":-48.2},"designations":[{"catalog":"Exoplanet","designation":"Kepler-553 c"}],"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."}