{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.673","julian_year":2026.673,"time":"2026-09-03T15:11:07.964Z","years_from_j2000":26.673,"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":"k2-91-b","name":"K2-91 b","class":"terrestrial_planet","category":"exoplanet","object_type":"Terrestrial planet","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":204.10376882947227,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":63.2182348,"dec_deg":24.2047218,"epoch_ra_deg":63.622022,"epoch_dec_deg":24.273664,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"K2-91","semi_major_axis_km":2453405.07948,"periapsis_km":null,"mass_kg":8.181869978874191e+24,"mass_msun":0.00000411478,"constellation":"Taurus","discovered":"2016","featured":false,"url":"https://spacecatalog.org/object/k2-91-b","radius_km":7015.910000000001,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"K2-91","host_v_mag":15.622,"eccentricity":0.09,"uncertainties":{"radius_km":[1148.058,1148.058],"distance_ly":[0.9142163267400317,0.9223702361829503],"eccentricity":[0.072789,0.168399],"host_mass_solar":[0.058,0.058],"inclination_deg":[1.29,0.96],"host_radius_solar":[0.041,0.041],"host_temperature_k":[104,104],"semi_major_axis_km":[164557.65777,164557.65777],"orbital_period_days":[0.000071,0.000071],"argument_of_periastron_deg":[110.4209,135.8729]},"host_mass_solar":0.292,"inclination_deg":88.62,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":0.284,"planets_in_system":1,"discovery_facility":"K2","host_temperature_k":3622,"orbital_period_days":1.419549,"transit_midpoint_bjd":2457065.4319,"equilibrium_temperature_k":726.81,"argument_of_periastron_deg":-23.36},"designations":[{"catalog":"Exoplanet","designation":"K2-91 b"},{"catalog":"Host star","designation":"K2-91"}],"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."}