{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.678","julian_year":2026.678,"time":"2026-09-05T18:48:18.291Z","years_from_j2000":26.678,"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":"trappist-1-d","name":"TRAPPIST-1 d","class":"terrestrial_planet","category":"exoplanet","object_type":"Terrestrial planet","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":40.540875096914824,"distance_method":"NASA Exoplanet Archive sy_dist (Gaia DR2, 2018A&A...616A...1G)","ra_deg":346.6263919,"dec_deg":-5.0434618,"epoch_ra_deg":346.973724,"epoch_dec_deg":-4.898394,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"TRAPPIST-1","semi_major_axis_km":3331544.580489,"periapsis_km":null,"mass_kg":2.3172011327030552e+24,"mass_msun":0.00000116535,"constellation":"Aquarius","discovered":"2016","featured":true,"url":"https://spacecatalog.org/object/trappist-1-d","radius_km":5025.942800000001,"radius_kind":null,"data_quality":null,"description":"The smallest of the seven TRAPPIST-1 worlds, sitting at the inner edge of the habitable zone.","properties":{"host_star":"TRAPPIST-1","host_v_mag":17.02,"eccentricity":0.00837,"uncertainties":{"mass_kg":[7.166601441349655e+22,7.166601441349655e+22],"radius_km":[63.781000000000006,70.1591],"distance_ly":[0.06101280156959809,0.06101280156959809],"eccentricity":[0.00093,0.00093],"host_mass_solar":[0.0023,0.0023],"inclination_deg":[0.077,0.077],"host_radius_solar":[0.0013,0.0013],"host_temperature_k":[26,26],"semi_major_axis_km":[28423.595433,28423.595433],"orbital_period_days":[0.000026,0.000026],"argument_of_periastron_deg":[6.17,6.17]},"host_mass_solar":0.0898,"inclination_deg":89.896,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":0.1192,"planets_in_system":7,"discovery_facility":"La Silla Observatory","host_spectral_type":"M8.0 V","host_temperature_k":2566,"orbital_period_days":4.049219,"transit_midpoint_bjd":2457670.1463014,"equilibrium_temperature_k":286.2,"argument_of_periastron_deg":-8.73},"designations":[{"catalog":"Exoplanet","designation":"TRAPPIST-1 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."}