{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.684","julian_year":2026.684,"time":"2026-09-07T17:57:13.914Z","years_from_j2000":26.684,"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-81817-c","name":"HD 81817 c","class":"gas_giant","category":"exoplanet","object_type":"Gas giant","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":877.7716130939629,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":144.2715659,"dec_deg":81.3263096,"epoch_ra_deg":145.190288,"epoch_dec_deg":81.205511,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"HD 81817","semi_major_axis_km":347815049.3775,"periapsis_km":null,"mass_kg":4.291469907588178e+28,"mass_msun":0.0215824,"constellation":"Draco","discovered":"2022","featured":false,"url":"https://spacecatalog.org/object/hd-81817-c","radius_km":76537.20000000001,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"HD 81817","host_v_mag":4.26489,"eccentricity":0.095,"uncertainties":{"mass_kg":[3.560881749131663e+27,3.528613630929827e+27],"distance_ly":[64.79096443343107,75.78895749003966],"eccentricity":[0.044,0.058],"host_mass_solar":[0.5,0.5],"host_radius_solar":[7.8,7.8],"host_temperature_k":[55,55],"semi_major_axis_km":[14211797.7165,13015014.750899998],"orbital_period_days":[2.12035,2.01914],"argument_of_periastron_deg":[29.119,35.347]},"host_mass_solar":4.3,"stars_in_system":1,"discovery_method":"Radial Velocity","host_radius_solar":83.8,"planets_in_system":2,"discovery_facility":"Multiple Observatories","host_spectral_type":"K3 III","host_temperature_k":4140,"orbital_period_days":622.97802,"periastron_epoch_bjd":2453031.768,"equilibrium_temperature_k":1198.52,"argument_of_periastron_deg":227.963},"designations":[{"catalog":"Exoplanet","designation":"HD 81817 c"},{"catalog":"Host star","designation":"HD 81817"}],"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."}