{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.680","julian_year":2026.68,"time":"2026-09-06T12:49:08.416Z","years_from_j2000":26.68,"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":"proxima-cen-d","name":"Proxima Cen d","class":"terrestrial_planet","category":"exoplanet","object_type":"Terrestrial planet","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":4.243914171212494,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":217.3934657,"dec_deg":-62.6761821,"epoch_ra_deg":217.911435,"epoch_dec_deg":-62.795993,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"Proxima Cen","semi_major_axis_km":4309914.654866999,"periapsis_km":null,"mass_kg":1.5527636456257586e+24,"mass_msun":7.80907e-7,"constellation":"Centaurus","discovered":"2025","featured":false,"url":"https://spacecatalog.org/object/proxima-cen-d","radius_km":4413.6452,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"Proxima Cen","host_v_mag":11.01,"eccentricity":0,"uncertainties":{"mass_kg":[2.2694237897607242e+23,2.2694237897607242e+23],"distance_ly":[0.001141547322008602,0.0011089316842369276],"host_mass_solar":[0.0022,0.0022],"host_radius_solar":[0.021,0.021],"host_temperature_k":[100,100],"semi_major_axis_km":[25431.638018999998,25431.638018999998],"orbital_period_days":[0.00035,0.00035],"argument_of_periastron_deg":[1.7,2]},"host_mass_solar":0.1221,"stars_in_system":3,"discovery_method":"Radial Velocity","host_radius_solar":0.141,"planets_in_system":2,"discovery_facility":"La Silla Observatory","host_spectral_type":"M5.5 V","host_temperature_k":2900,"orbital_period_days":5.12338,"periastron_epoch_bjd":2460557.55,"equilibrium_temperature_k":282,"argument_of_periastron_deg":4},"designations":[{"catalog":"Exoplanet","designation":"Proxima Cen d"},{"catalog":"Host star","designation":"Proxima Cen"}],"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."}