{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.673","julian_year":2026.673,"time":"2026-09-03T23:03:49.978Z","years_from_j2000":26.673,"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-42-c","name":"Kepler-42 c","class":"terrestrial_planet","category":"exoplanet","object_type":"Terrestrial planet","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":130.65661413143883,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":292.2196,"dec_deg":44.6173667,"epoch_ra_deg":292.42622,"epoch_dec_deg":44.67203,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"Kepler-42","semi_major_axis_km":897587.2241999999,"periapsis_km":null,"mass_kg":3.6034269263892846e+26,"mass_msun":0.000181222,"constellation":"Cygnus","discovered":"2011","featured":false,"url":"https://spacecatalog.org/object/kepler-42-c","radius_km":4656.013,"radius_kind":null,"data_quality":"The published mass and radius imply a density no material has. One of the two is likely an upper limit rather than a measurement.","description":null,"properties":{"host_star":"Kepler-42","host_v_mag":16.7,"eccentricity":0,"uncertainties":{"radius_km":[1275.6200000000001,1275.6200000000001],"distance_ly":[0.21102317638273296,0.21200164551588324],"eccentricity":[0,0.1],"host_mass_solar":[0.05,0.05],"host_radius_solar":[0.04,0.04],"host_temperature_k":[174,174],"orbital_period_days":[9.7e-7,9.7e-7]},"host_mass_solar":0.13,"inclination_deg":81.11,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":0.17,"planets_in_system":3,"discovery_facility":"Kepler","host_spectral_type":"M","host_temperature_k":3068,"orbital_period_days":0.45328509,"transit_midpoint_bjd":2454966.86952,"equilibrium_temperature_k":720},"designations":[{"catalog":"Exoplanet","designation":"Kepler-42 c"},{"catalog":"Host star","designation":"Kepler-42"}],"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."}