{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.687","julian_year":2026.687,"time":"2026-09-08T20:08:27.944Z","years_from_j2000":26.687,"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":"mu-leo-b","name":"μ Leo b","class":"gas_giant","category":"exoplanet","object_type":"Gas giant","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":106.35339780225341,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":148.1898673,"dec_deg":26.0067142,"epoch_ra_deg":148.57329,"epoch_dec_deg":25.880535,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"μ Leo","semi_major_axis_km":164557657.77,"periapsis_km":null,"mass_kg":4.555569649551264e+27,"mass_msun":0.00229106,"constellation":"Leo","discovered":"2014","featured":false,"url":"https://spacecatalog.org/object/mu-leo-b","radius_km":84828.73000000001,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"μ Leo","host_v_mag":3.86648,"eccentricity":0.09,"uncertainties":{"mass_kg":[7.590625359962842e+26,7.590625359962842e+26],"distance_ly":[1.474552983657397,1.474552983657397],"eccentricity":[0.06,0.06],"host_mass_solar":[0.1,0.1],"host_radius_solar":[0.2,0.2],"host_temperature_k":[27.5,27.5],"semi_major_axis_km":[14959787.07,14959787.07],"orbital_period_days":[1.2,1.2],"argument_of_periastron_deg":[16,16]},"host_mass_solar":1.5,"stars_in_system":1,"discovery_method":"Radial Velocity","host_radius_solar":11.4,"planets_in_system":1,"discovery_facility":"Bohyunsan Optical Astronomical Observatory","host_spectral_type":"K2 III","host_temperature_k":4538.2,"orbital_period_days":357.8,"periastron_epoch_bjd":2452921,"equilibrium_temperature_k":704.49,"argument_of_periastron_deg":227.1},"designations":[{"catalog":"Exoplanet","designation":"mu Leo b"},{"catalog":"Host star","designation":"mu Leo"}],"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."}