{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.682","julian_year":2026.682,"time":"2026-09-07T06:33:22.068Z","years_from_j2000":26.682,"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-c","name":"LP 791-18 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":86.40763067936368,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":165.6904843,"dec_deg":-16.4064445,"epoch_ra_deg":166.023259,"epoch_dec_deg":-16.550924,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"LP 791-18","semi_major_axis_km":4429592.951427,"periapsis_km":null,"mass_kg":4.276072193338628e+25,"mass_msun":0.000021505,"constellation":"Crater","discovered":"2019","featured":false,"url":"https://spacecatalog.org/object/lp-791-18-c","radius_km":15868.712800000001,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"LP 791-18","host_v_mag":16.91,"eccentricity":0.0001,"uncertainties":{"mass_kg":[3.8819091140643965e+24,3.8819091140643965e+24],"radius_km":[612.2976000000001,612.2976000000001],"distance_ly":[0.2080877689832823,0.2087400817387158],"eccentricity":[0.0001,0.0001],"host_mass_solar":[0.005,0.005],"inclination_deg":[0.05,0.05],"host_radius_solar":[0.007,0.007],"host_temperature_k":[55,55],"semi_major_axis_km":[53855.233452,52359.254745],"orbital_period_days":[0.0000014,0.0000012]},"host_mass_solar":0.139,"inclination_deg":89.94,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":0.182,"planets_in_system":3,"discovery_facility":"Transiting Exoplanet Survey Satellite (TESS)","host_spectral_type":"M(6.1 +/- 0.7) V","host_temperature_k":2960,"orbital_period_days":4.98991,"transit_midpoint_bjd":2458546.50923,"equilibrium_temperature_k":324.4},"designations":[{"catalog":"Exoplanet","designation":"LP 791-18 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":"2026-09-02T19:50:56.720Z","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."}