{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.668","julian_year":2026.668,"time":"2026-09-01T20:12:06.699Z","years_from_j2000":26.668,"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":"kepler-308-c","name":"Kepler-308 c","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":4357.188281193519,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":295.7852423,"dec_deg":40.4395753,"epoch_ra_deg":296.013655,"epoch_dec_deg":40.502781,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"Kepler-308","semi_major_axis_km":18400538.0961,"periapsis_km":null,"mass_kg":3.171221137797222e+25,"mass_msun":0.0000159485,"constellation":"Cygnus","discovered":"2014","featured":false,"url":"https://spacecatalog.org/object/kepler-308-c","radius_km":13776.696000000002,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"Kepler-308","host_v_mag":16.019,"eccentricity":0,"uncertainties":{"radius_km":[6633.224,6633.224],"distance_ly":[225.5371351911281,251.0751795663491],"host_mass_solar":[0.053,0.055],"host_radius_solar":[0.452,0.452],"host_temperature_k":[200,200],"orbital_period_days":[0.000171,0.000171]},"host_mass_solar":0.92,"inclination_deg":89.97,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":0.941,"planets_in_system":2,"discovery_facility":"Kepler","host_temperature_k":5895,"orbital_period_days":15.38231,"transit_midpoint_bjd":2454972.08277,"equilibrium_temperature_k":714},"designations":[{"catalog":"Exoplanet","designation":"Kepler-308 c"}],"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":"2026-08-30T09:56:50.739Z","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."}