{"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":"2026-09-08T19:05:17.723Z","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":"k2-171-b","name":"K2-171 b","class":"neptune_like_planet","category":"exoplanet","object_type":"Neptune-like planet","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":1976.9251291269427,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":332.3407712,"dec_deg":-13.4288624,"epoch_ra_deg":332.701961,"epoch_dec_deg":-13.297209,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"K2-171","semi_major_axis_km":null,"periapsis_km":null,"mass_kg":4.5925970903315705e+25,"mass_msun":0.0000230968,"constellation":"Aquarius","discovered":"2018","featured":false,"url":"https://spacecatalog.org/object/k2-171-b","radius_km":17135.225192105,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"K2-171","host_v_mag":12.745,"uncertainties":{"radius_km":[2114.591893607,2552.760092573],"distance_ly":[57.641616633880055,61.14453613055789],"host_mass_solar":[0.027038,0.060192],"inclination_deg":[9.64089,3.65033],"host_radius_solar":[0.193599,0.221392],"host_temperature_k":[50,50],"orbital_period_days":[0.001519,0.001731]},"host_mass_solar":0.891587,"inclination_deg":85.04821,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":1.717458,"planets_in_system":1,"discovery_facility":"K2","host_temperature_k":5250,"orbital_period_days":5.628466,"transit_midpoint_bjd":2456979.46712},"designations":[{"catalog":"Exoplanet","designation":"K2-171 b"},{"catalog":"Host star","designation":"K2-171"}],"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."}