{"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":"2026-09-04T05:50:03.200Z","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":"k2-17-b","name":"K2-17 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":408.041197906309,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":178.3296746,"dec_deg":6.4123178,"epoch_ra_deg":178.674448,"epoch_dec_deg":6.262923,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"K2-17","semi_major_axis_km":17802146.6133,"periapsis_km":null,"mass_kg":3.3444140059631724e+25,"mass_msun":0.0000168195,"constellation":"Virgo","discovered":"2015","featured":false,"url":"https://spacecatalog.org/object/k2-17-b","radius_km":14223.163,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"K2-17","host_v_mag":13.411,"eccentricity":0.18,"uncertainties":{"radius_km":[1275.6200000000001,1275.6200000000001],"distance_ly":[2.1428474015990044,2.162416784262009],"eccentricity":[0.152247,0.201126],"host_mass_solar":[0.05,0.02],"inclination_deg":[0.2,0.4],"host_radius_solar":[0.03,0.02],"host_temperature_k":[47,56],"semi_major_axis_km":[299195.7414,299195.7414],"orbital_period_days":[0.00152,0.00152],"argument_of_periastron_deg":[130.8055,83.4772]},"host_mass_solar":0.71,"inclination_deg":89.08,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":0.66,"planets_in_system":1,"discovery_facility":"K2","host_spectral_type":"K7","host_temperature_k":4320,"orbital_period_days":17.96753,"transit_midpoint_bjd":2456817.9462,"equilibrium_temperature_k":487,"argument_of_periastron_deg":52.06},"designations":[{"catalog":"Exoplanet","designation":"K2-17 b"},{"catalog":"Host star","designation":"K2-17"}],"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."}