{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.677","julian_year":2026.677,"time":"2026-09-05T02:53:52.926Z","years_from_j2000":26.677,"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":"k2-55-b","name":"K2-55 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":520.2911768613034,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":333.7518786,"dec_deg":-17.2508002,"epoch_ra_deg":334.116964,"epoch_dec_deg":-17.117488,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"K2-55","semi_major_axis_km":5214981.772602,"periapsis_km":null,"mass_kg":2.627753861828207e+26,"mass_msun":0.000132154,"constellation":"Aquarius","discovered":"2016","featured":false,"url":"https://spacecatalog.org/object/k2-55-b","radius_km":28254.983,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"K2-55","host_v_mag":13.519,"eccentricity":0.07,"uncertainties":{"mass_kg":[3.1652489699294308e+25,3.1652489699294308e+25],"radius_km":[2040.9920000000002,1849.649],"distance_ly":[2.36463373844639,2.380941557332227],"eccentricity":[0.06,0.13],"host_mass_solar":[0.069,0.069],"inclination_deg":[1,1.1],"host_radius_solar":[0.04,0.043],"host_temperature_k":[100,107],"semi_major_axis_km":[116686.33914599998,116686.33914599998],"orbital_period_days":[0.000029,0.000029],"argument_of_periastron_deg":[140.3,115.4]},"host_mass_solar":0.688,"inclination_deg":88.2,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":0.715,"planets_in_system":1,"discovery_facility":"K2","host_temperature_k":4300,"orbital_period_days":2.849271,"transit_midpoint_bjd":2456983.4229,"equilibrium_temperature_k":900,"argument_of_periastron_deg":23.9},"designations":[{"catalog":"Exoplanet","designation":"K2-55 b"},{"catalog":"Host star","designation":"K2-55"}],"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."}