{"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":"2026-09-04T01:18:16.947Z","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":"k2-338-b","name":"K2-338 b","class":"terrestrial_planet","category":"exoplanet","object_type":"Terrestrial planet","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":511.90569639020595,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":124.3609294,"dec_deg":17.0241557,"epoch_ra_deg":124.743006,"epoch_dec_deg":16.941253,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"K2-338","semi_major_axis_km":null,"periapsis_km":null,"mass_kg":6.44994129721469e+24,"mass_msun":0.00000324377,"constellation":"Cancer","discovered":"2021","featured":false,"url":"https://spacecatalog.org/object/k2-338-b","radius_km":6569.443,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"K2-338","host_v_mag":13.322,"uncertainties":{"radius_km":[318.90500000000003,701.591],"distance_ly":[1.9471535749689581,1.9634613938547953],"host_mass_solar":[0.02,0.02],"host_radius_solar":[0.01,0.01],"host_temperature_k":[81,91],"orbital_period_days":[0.000012,0.000012]},"host_mass_solar":0.66,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":0.63,"planets_in_system":1,"discovery_facility":"K2","host_temperature_k":4558,"orbital_period_days":3.850614,"transit_midpoint_bjd":2457141.526349,"equilibrium_temperature_k":783},"designations":[{"catalog":"Exoplanet","designation":"K2-338 b"},{"catalog":"Host star","designation":"K2-338"}],"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."}