{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.679","julian_year":2026.679,"time":"2026-09-06T03:05:35.105Z","years_from_j2000":26.679,"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":"hd-181720-b","name":"HD 181720 b","class":"gas_giant","category":"exoplanet","object_type":"Gas giant","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":196.3611425788545,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":290.7212224,"dec_deg":-32.9208401,"epoch_ra_deg":291.156281,"epoch_dec_deg":-32.869534,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"HD 181720","semi_major_axis_km":276756060.795,"periapsis_km":null,"mass_kg":7.592536453680537e+26,"mass_msun":0.00038184,"constellation":"Sagittarius","discovered":"2009","featured":false,"url":"https://spacecatalog.org/object/hd-181720-b","radius_km":89293.40000000001,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"HD 181720","host_v_mag":7.84,"eccentricity":0.26,"uncertainties":{"mass_kg":[1.1388804680520805e+26,1.1388804680520805e+26],"distance_ly":[0.7873414958082187,0.7935384669848367],"eccentricity":[0.06,0.06],"host_mass_solar":[0.2,0.2],"host_radius_solar":[0.07,0.07],"host_temperature_k":[37,37],"semi_major_axis_km":[5983914.828,5983914.828],"orbital_period_days":[14,14],"argument_of_periastron_deg":[12,12]},"host_mass_solar":1.03,"stars_in_system":1,"discovery_method":"Radial Velocity","host_radius_solar":1.5,"planets_in_system":1,"discovery_facility":"La Silla Observatory","host_spectral_type":"G1 V","host_temperature_k":5736,"orbital_period_days":956,"periastron_epoch_bjd":2453631,"equilibrium_temperature_k":249.06,"argument_of_periastron_deg":177},"designations":[{"catalog":"Exoplanet","designation":"HD 181720 b"},{"catalog":"Host star","designation":"HD 181720"}],"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."}