{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.677","julian_year":2026.677,"time":"2026-09-05T09:17:34.308Z","years_from_j2000":26.677,"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-153557-d","name":"HD 153557 d","class":"gas_giant","category":"exoplanet","object_type":"Gas giant","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":58.51636803891636,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":254.4706516,"dec_deg":47.3678558,"epoch_ra_deg":254.659,"epoch_dec_deg":47.325853,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"HD 153557","semi_major_axis_km":3208724728.6443,"periapsis_km":null,"mass_kg":5.211111276173296e+28,"mass_msun":0.0262074,"constellation":"Hercules","discovered":"2022","featured":false,"url":"https://spacecatalog.org/object/hd-153557-d","radius_km":75899.39,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"HD 153557","host_v_mag":7.83,"eccentricity":0.152,"uncertainties":{"mass_kg":[6.635843600737551e+27,6.749731076722955e+27],"distance_ly":[0.027397135728206446,0.027397135728206446],"eccentricity":[0.047,0.06],"host_mass_solar":[0.091,0.091],"inclination_deg":[0.935,0.964],"host_radius_solar":[0.039756,0.063359],"host_temperature_k":[159.51,96.07],"semi_major_axis_km":[261197882.2422,222452033.7309],"orbital_period_days":[4234.02733,3874.17546],"argument_of_periastron_deg":[7.584,7.972]},"host_mass_solar":0.79,"inclination_deg":14.324,"stars_in_system":1,"discovery_method":"Radial Velocity","host_radius_solar":0.745171,"planets_in_system":3,"discovery_facility":"Multiple Observatories","host_spectral_type":"K0","host_temperature_k":4837,"orbital_period_days":40654.64809,"periastron_epoch_bjd":2425426.661,"equilibrium_temperature_k":43.47,"argument_of_periastron_deg":6.861},"designations":[{"catalog":"Exoplanet","designation":"HD 153557 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."}