{"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":"2026-09-06T13:03:14.180Z","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":"hd-17156-b","name":"HD 17156 b","class":"gas_giant","category":"exoplanet","object_type":"Gas giant","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":254.68344757302938,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":42.4366123,"dec_deg":71.7530882,"epoch_ra_deg":43.084698,"epoch_dec_deg":71.864451,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"HD 17156","semi_major_axis_km":24414372.49824,"periapsis_km":null,"mass_kg":6.187886195206909e+27,"mass_msun":0.00311198,"constellation":"Cassiopeia","discovered":"2007","featured":false,"url":"https://spacecatalog.org/object/hd-17156-b","radius_km":78212.247810909,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"HD 17156","host_v_mag":8.17,"eccentricity":0.6772,"uncertainties":{"mass_kg":[2.0879370597323927e+26,2.0879370597323927e+26],"radius_km":[2144.759987702,2216.25198304],"distance_ly":[0.7772306480989996,0.781796837387034],"eccentricity":[0.0044,0.0045],"host_mass_solar":[0.062,0.064],"inclination_deg":[0.34,0.37],"host_radius_solar":[0.036,0.038],"host_temperature_k":[72,76],"semi_major_axis_km":[403914.25088999997,403914.25088999997],"orbital_period_days":[0.0000061,0.0000061],"argument_of_periastron_deg":[0.37,0.37]},"host_mass_solar":1.285,"inclination_deg":86.51,"stars_in_system":1,"discovery_method":"Radial Velocity","host_radius_solar":1.517,"planets_in_system":1,"discovery_facility":"Subaru Telescope","host_spectral_type":"G5","host_temperature_k":6046,"orbital_period_days":21.2164294,"periastron_epoch_bjd":2458788.1332,"transit_midpoint_bjd":2458809.07037,"equilibrium_temperature_k":888,"argument_of_periastron_deg":122.06},"designations":[{"catalog":"Exoplanet","designation":"HD 17156 b"},{"catalog":"Host star","designation":"HD 17156"}],"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."}