{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.678","julian_year":2026.678,"time":"2026-09-05T16:00:40.606Z","years_from_j2000":26.678,"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":"k2-198-b","name":"K2-198 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":360.62132215007165,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":198.8436817,"dec_deg":-6.4649888,"epoch_ra_deg":199.193178,"epoch_dec_deg":-6.60711,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"K2-198","semi_major_axis_km":null,"periapsis_km":null,"mass_kg":9.734633624499948e+25,"mass_msun":0.0000489569,"constellation":"Virgo","discovered":"2018","featured":false,"url":"https://spacecatalog.org/object/k2-198-b","radius_km":26717.860900000003,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"K2-198","host_v_mag":10.971,"uncertainties":{"radius_km":[625.0538,1454.2068000000002],"distance_ly":[2.804944848363993,2.8506067412443374],"host_mass_solar":[0.045,0.091],"inclination_deg":[0.027,0.094],"host_radius_solar":[0.016,0.035],"host_temperature_k":[49.2,99],"orbital_period_days":[0.0000035,0.0000071]},"host_mass_solar":0.799,"inclination_deg":88.904,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":0.757,"planets_in_system":3,"discovery_facility":"K2","host_temperature_k":5212.9,"orbital_period_days":17.0428683,"transit_midpoint_bjd":2457204.5687,"equilibrium_temperature_k":715.8},"designations":[{"catalog":"Exoplanet","designation":"K2-198 b"},{"catalog":"Host star","designation":"K2-198"}],"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."}