{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.675","julian_year":2026.675,"time":"2026-09-04T17:08:54.604Z","years_from_j2000":26.675,"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":"k2-261-b","name":"K2-261 b","class":"gas_giant","category":"exoplanet","object_type":"Gas giant","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":695.6361070856018,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":163.0323119,"dec_deg":0.493167,"epoch_ra_deg":163.376756,"epoch_dec_deg":0.35069,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"K2-261","semi_major_axis_km":16246328.758019999,"periapsis_km":null,"mass_kg":4.118930381531806e+26,"mass_msun":0.000207147,"constellation":"Leo","discovered":"2018","featured":false,"url":"https://spacecatalog.org/object/k2-261-b","radius_km":59123.883843824,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"K2-261","host_v_mag":10.612,"eccentricity":0.274,"uncertainties":{"mass_kg":[5.5045613375028394e+25,4.745311502377886e+25],"radius_km":[2144.759987702,2359.235973716],"distance_ly":[6.33069529148199,6.441588459905683],"eccentricity":[0.061,0.065],"host_mass_solar":[0.047,0.042],"inclination_deg":[0.57,0.85],"host_radius_solar":[0.068,0.071],"host_temperature_k":[110,110],"semi_major_axis_km":[179517.44483999998,179517.44483999998],"orbital_period_days":[0.0000044,0.0000044],"argument_of_periastron_deg":[15,13]},"host_mass_solar":1.107,"inclination_deg":88.58,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":1.663,"planets_in_system":1,"discovery_facility":"K2","host_spectral_type":"G7 IV/V","host_temperature_k":5490,"orbital_period_days":11.6334681,"periastron_epoch_bjd":2457907.58,"transit_midpoint_bjd":2458151.14392,"equilibrium_temperature_k":1036,"argument_of_periastron_deg":145},"designations":[{"catalog":"Exoplanet","designation":"K2-261 b"},{"catalog":"Host star","designation":"K2-261"}],"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."}