{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.686","julian_year":2026.686,"time":"2026-09-08T17:08:46.976Z","years_from_j2000":26.686,"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":"55-cnc-b-c","name":"55 Cnc B c","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":40.69550971685123,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":133.167908,"dec_deg":28.3152863,"epoch_ra_deg":133.571534,"epoch_dec_deg":28.21424,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"55 Cnc B","semi_major_axis_km":19447723.191,"periapsis_km":null,"mass_kg":3.1652489699294308e+25,"mass_msun":0.0000159185,"constellation":"Cancer","discovered":"2025","featured":false,"url":"https://spacecatalog.org/object/55-cnc-b-c","radius_km":13776.696000000002,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"55 Cnc B","host_v_mag":13.152,"eccentricity":0,"uncertainties":{"mass_kg":[8.361035014907931e+24,8.361035014907931e+24],"distance_ly":[0.05577274058956313,0.05577274058956313],"host_mass_solar":[0.02,0.02],"host_radius_solar":[0.066,0.066],"host_temperature_k":[31,31],"semi_major_axis_km":[448793.61209999997,448793.61209999997],"orbital_period_days":[0.035,0.035]},"host_mass_solar":0.26,"stars_in_system":2,"discovery_method":"Radial Velocity","host_radius_solar":0.274,"planets_in_system":7,"discovery_facility":"Mauna Kea Observatory","host_spectral_type":"M4.5 V","host_temperature_k":3286,"orbital_period_days":33.747,"transit_midpoint_bjd":2455491.8,"equilibrium_temperature_k":230.04},"designations":[{"catalog":"Exoplanet","designation":"55 Cnc B c"}],"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."}