{"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":"2026-09-06T19:55:12.446Z","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":"k2-139-b","name":"K2-139 b","class":"gas_giant","category":"exoplanet","object_type":"Gas giant","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":501.8111564998727,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":289.066707,"dec_deg":-17.9107147,"epoch_ra_deg":289.456744,"epoch_dec_deg":-17.863542,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"K2-139","semi_major_axis_km":26867777.577719998,"periapsis_km":null,"mass_kg":7.345779018935918e+26,"mass_msun":0.00036943,"constellation":"Sagittarius","discovered":"2017","featured":false,"url":"https://spacecatalog.org/object/k2-139-b","radius_km":58104.491,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"K2-139","host_v_mag":11.652,"eccentricity":0.12,"uncertainties":{"mass_kg":[1.4236005850651006e+26,1.5754513141387112e+26],"radius_km":[1084.277,1084.277],"distance_ly":[3.003900238771207,3.039777440320049],"eccentricity":[0.08,0.12],"host_mass_solar":[0.02,0.02],"inclination_deg":[0.19809,0.25667],"host_radius_solar":[0.01,0.01],"host_temperature_k":[68,68],"semi_major_axis_km":[224396.80604999998,224396.80604999998],"orbital_period_days":[0.000528,0.000551],"argument_of_periastron_deg":[79,175]},"host_mass_solar":0.96,"inclination_deg":89.55668,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":0.88,"planets_in_system":1,"discovery_facility":"K2","host_spectral_type":"K0 V","host_temperature_k":5370,"orbital_period_days":28.380619,"transit_midpoint_bjd":2457325.8175,"equilibrium_temperature_k":524,"argument_of_periastron_deg":124},"designations":[{"catalog":"Exoplanet","designation":"K2-139 b"},{"catalog":"Host star","designation":"K2-139"}],"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."}