{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.683","julian_year":2026.683,"time":"2026-09-07T14:38:34.286Z","years_from_j2000":26.683,"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":"tau-cet-h","name":"τ Cet h","class":"terrestrial_planet","category":"exoplanet","object_type":"Terrestrial planet","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":11.751544751685351,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":26.0093029,"dec_deg":-15.9337987,"epoch_ra_deg":26.335399,"epoch_dec_deg":-15.798538,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"τ Cet","semi_major_axis_km":36352282.58009999,"periapsis_km":null,"mass_kg":1.0929067198058225e+25,"mass_msun":0.00000549639,"constellation":"Cetus","discovered":"2017","featured":false,"url":"https://spacecatalog.org/object/tau-cet-h","radius_km":7589.939,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"τ Cet","host_v_mag":3.49607,"eccentricity":0.23,"uncertainties":{"mass_kg":[1.5527636456257586e+24,4.0610741500981384e+24],"distance_ly":[0.02201555549588018,0.022113402409195203],"eccentricity":[0.15,0.16],"host_mass_solar":[0.012,0.012],"host_radius_solar":[0.02,0.02],"host_temperature_k":[17,17],"semi_major_axis_km":[448793.61209999997,448793.61209999997],"orbital_period_days":[0.1,0.08],"argument_of_periastron_deg":[48.13,37.24]},"host_mass_solar":0.783,"stars_in_system":1,"discovery_method":"Radial Velocity","host_radius_solar":0.83,"planets_in_system":3,"discovery_facility":"Multiple Observatories","host_spectral_type":"G8.5V","host_temperature_k":5310,"orbital_period_days":49.41,"equilibrium_temperature_k":473.22,"argument_of_periastron_deg":7.45},"designations":[{"catalog":"Exoplanet","designation":"tau Cet h"}],"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."}