{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.681","julian_year":2026.681,"time":"2026-09-06T16:20:24.314Z","years_from_j2000":26.681,"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":"lp-791-18-d","name":"LP 791-18 d","class":"terrestrial_planet","category":"exoplanet","object_type":"Terrestrial planet","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":86.40763067936368,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":165.6904843,"dec_deg":-16.4064445,"epoch_ra_deg":166.023232,"epoch_dec_deg":-16.550913,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"LP 791-18","semi_major_axis_km":2979989.5843439996,"periapsis_km":null,"mass_kg":5.434672759690155e+24,"mass_msun":0.00000273318,"constellation":"Crater","discovered":"2023","featured":false,"url":"https://spacecatalog.org/object/lp-791-18-d","radius_km":6582.199200000001,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"LP 791-18","host_v_mag":16.91,"eccentricity":0.0011,"uncertainties":{"mass_kg":[1.134711894880362e+24,1.134711894880362e+24],"radius_km":[274.2583,280.6364],"distance_ly":[0.2080877689832823,0.2087400817387158],"eccentricity":[0.0008,0.001],"host_mass_solar":[0.005,0.005],"inclination_deg":[0.41,0.41],"host_radius_solar":[0.007,0.007],"host_temperature_k":[55,55],"semi_major_axis_km":[35903.488968,35903.488968],"orbital_period_days":[0.00013,0.00013]},"host_mass_solar":0.139,"inclination_deg":89.34,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":0.182,"planets_in_system":3,"discovery_facility":"Spitzer Space Telescope","host_spectral_type":"M(6.1 +/- 0.7) V","host_temperature_k":2960,"orbital_period_days":2.75485,"transit_midpoint_bjd":2458546.37888,"equilibrium_temperature_k":395.5},"designations":[{"catalog":"Exoplanet","designation":"LP 791-18 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":"2026-09-02T19:50:56.720Z","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."}