{"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":"2026-09-06T17:44:31.878Z","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":"k2-186-b","name":"K2-186 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":1078.7263420965799,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":135.3350487,"dec_deg":18.8252879,"epoch_ra_deg":135.715439,"epoch_dec_deg":18.720173,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"K2-186","semi_major_axis_km":null,"periapsis_km":null,"mass_kg":6.091611225147206e+25,"mass_msun":0.0000306356,"constellation":"Cancer","discovered":"2018","featured":false,"url":"https://spacecatalog.org/object/k2-186-b","radius_km":20231.829352399,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"K2-186","host_v_mag":12.413,"uncertainties":{"radius_km":[1038.87704639,1681.1534384770002],"distance_ly":[17.201487360781048,17.755953202899512],"host_mass_solar":[0.027107,0.022671],"inclination_deg":[0.5924,0.33438],"host_radius_solar":[0.041402,0.075464],"host_temperature_k":[50,50],"orbital_period_days":[0.004316,0.003288]},"host_mass_solar":1.018617,"inclination_deg":89.52426,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":0.98083,"planets_in_system":1,"discovery_facility":"K2","host_temperature_k":5784,"orbital_period_days":41.474219,"transit_midpoint_bjd":2457154.8454},"designations":[{"catalog":"Exoplanet","designation":"K2-186 b"},{"catalog":"Host star","designation":"K2-186"}],"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."}