{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.681","julian_year":2026.681,"time":"2026-09-06T14:03:42.264Z","years_from_j2000":26.681,"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":"k2-208-b","name":"K2-208 b","class":"super_earth","category":"exoplanet","object_type":"Super-Earth","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":837.8533340252106,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":20.7789809,"dec_deg":0.8890076,"epoch_ra_deg":21.124051,"epoch_dec_deg":1.029499,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"K2-208","semi_major_axis_km":7297384.132745999,"periapsis_km":null,"mass_kg":2.0603979143880257e+25,"mass_msun":0.000010362,"constellation":"Cetus","discovered":"2018","featured":false,"url":"https://spacecatalog.org/object/k2-208-b","radius_km":10680.904792332001,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"K2-208","host_v_mag":12.577,"eccentricity":0.37,"uncertainties":{"radius_km":[586.234387284,786.4120124990001],"distance_ly":[10.254356515414413,10.505496926256306],"eccentricity":[0.21,0.31],"host_mass_solar":[0.042,0.045],"inclination_deg":[0.76,1.8],"host_radius_solar":[0.03,0.033],"host_temperature_k":[100,100],"semi_major_axis_km":[118182.31785299999,122670.25397399999],"orbital_period_days":[0.00023,0.00023],"argument_of_periastron_deg":[110,160]},"host_mass_solar":0.881,"inclination_deg":86.94,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":0.872,"planets_in_system":1,"discovery_facility":"K2","host_temperature_k":5500,"orbital_period_days":4.19097,"transit_midpoint_bjd":2457430.039,"equilibrium_temperature_k":1122,"argument_of_periastron_deg":-210},"designations":[{"catalog":"Exoplanet","designation":"K2-208 b"},{"catalog":"Host star","designation":"K2-208"}],"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."}