{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.682","julian_year":2026.682,"time":"2026-09-06T22:03:15.001Z","years_from_j2000":26.682,"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":"hat-p-17-c","name":"HAT-P-17 c","class":"gas_giant","category":"exoplanet","object_type":"Gas giant","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":301.3133725824368,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":324.5359781,"dec_deg":30.4881882,"epoch_ra_deg":324.828069,"epoch_dec_deg":30.608902,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"HAT-P-17","semi_major_axis_km":837748075.9199998,"periapsis_km":null,"mass_kg":6.453524597935363e+27,"mass_msun":0.00324557,"constellation":"Cygnus","discovered":"2012","featured":false,"url":"https://spacecatalog.org/object/hat-p-17-c","radius_km":83553.11,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"HAT-P-17","host_v_mag":10.375,"eccentricity":0.39,"uncertainties":{"mass_kg":[1.328807350583582e+27,2.0878698865798663e+27],"distance_ly":[1.566202925795802,1.5821845883039223],"eccentricity":[0.17,0.23],"host_mass_solar":[0.078885,0.154252],"host_radius_solar":[0.042297,0.035869],"host_temperature_k":[91.85,118.21],"semi_major_axis_km":[209437018.97999996,523592547.4499999],"orbital_period_days":[2100,7700],"argument_of_periastron_deg":[6.7,5.3]},"host_mass_solar":0.92,"stars_in_system":1,"discovery_method":"Radial Velocity","host_radius_solar":0.838682,"planets_in_system":2,"discovery_facility":"W. M. Keck Observatory","host_spectral_type":"K","host_temperature_k":5336.96,"orbital_period_days":5584,"periastron_epoch_bjd":2454885,"equilibrium_temperature_k":99.59,"argument_of_periastron_deg":181.5},"designations":[{"catalog":"Exoplanet","designation":"HAT-P-17 c"}],"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."}