{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.678","julian_year":2026.678,"time":"2026-09-05T12:33:59.206Z","years_from_j2000":26.678,"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":"xo-4-b","name":"XO-4 b","class":"gas_giant","category":"exoplanet","object_type":"Gas giant","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":889.2816716635866,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":110.3880285,"dec_deg":58.2681094,"epoch_ra_deg":110.959509,"epoch_dec_deg":58.217457,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"XO-4","semi_major_axis_km":8263786.377467999,"periapsis_km":null,"mass_kg":2.6953504410565906e+27,"mass_msun":0.00135553,"constellation":"Lynx","discovered":"2010","featured":false,"url":"https://spacecatalog.org/object/xo-4-b","radius_km":89365.153625,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"XO-4","host_v_mag":10.814,"eccentricity":0,"uncertainties":{"mass_kg":[3.606454815498255e+26,3.606454815498255e+26],"radius_km":[5719.369832,5719.369832],"distance_ly":[9.311764583813025,9.504196846665904],"host_mass_solar":[0.22,0.22],"inclination_deg":[0.6,0.6],"host_radius_solar":[0.09,0.09],"host_temperature_k":[70,70],"semi_major_axis_km":[41887.40379599999,40391.425089],"orbital_period_days":[0.000004,0.000004],"argument_of_periastron_deg":[160,39]},"host_mass_solar":1.1,"inclination_deg":88.8,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":1.45,"planets_in_system":1,"discovery_facility":"Lowell Observatory","host_spectral_type":"F5 V","host_temperature_k":6397,"orbital_period_days":4.12508,"transit_midpoint_bjd":2456878.47303,"equilibrium_temperature_k":1630,"argument_of_periastron_deg":240},"designations":[{"catalog":"Exoplanet","designation":"XO-4 b"},{"catalog":"Host star","designation":"XO-4"}],"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."}