{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.669","julian_year":2026.669,"time":"2026-09-02T08:17:10.070Z","years_from_j2000":26.669,"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":"k2-384-d","name":"K2-384 d","class":"super_earth","category":"exoplanet","object_type":"Super-Earth","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":269.6018402897933,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":20.4998403,"dec_deg":0.7509701,"epoch_ra_deg":20.844572,"epoch_dec_deg":0.891632,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"K2-384","semi_major_axis_km":null,"periapsis_km":null,"mass_kg":1.5049863026834276e+25,"mass_msun":0.00000756879,"constellation":"Cetus","discovered":"2022","featured":false,"url":"https://spacecatalog.org/object/k2-384-d","radius_km":8878.3152,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"K2-384","host_v_mag":16.12,"uncertainties":{"radius_km":[478.3575,752.6158],"distance_ly":[2.2530882572672635,2.290596240704689],"host_mass_solar":[0.009,0.009],"host_radius_solar":[0.01,0.011],"host_temperature_k":[138,138],"orbital_period_days":[0.000498,0.000719]},"host_mass_solar":0.33,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":0.348,"planets_in_system":5,"discovery_facility":"K2","host_spectral_type":"M4 V","host_temperature_k":3623,"orbital_period_days":6.679582,"transit_midpoint_bjd":2457392.4243},"designations":[{"catalog":"Exoplanet","designation":"K2-384 d"}],"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":"2026-09-01T22:58:55.274Z","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."}