{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.674","julian_year":2026.674,"time":"2026-09-04T08:35:52.659Z","years_from_j2000":26.674,"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":"kepler-561-b","name":"Kepler-561 b","class":"gas_giant","category":"exoplanet","object_type":"Gas giant","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":2026.663976728746,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":293.7471107,"dec_deg":45.1071981,"epoch_ra_deg":293.952877,"epoch_dec_deg":45.165556,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"Kepler-561","semi_major_axis_km":43766353.05199199,"periapsis_km":null,"mass_kg":2.3112289648352638e+26,"mass_msun":0.000116235,"constellation":"Cygnus","discovered":"2016","featured":false,"url":"https://spacecatalog.org/object/kepler-561-b","radius_km":44391.576,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"Kepler-561","host_v_mag":14.427,"eccentricity":0,"uncertainties":{"radius_km":[3890.641,7717.501],"distance_ly":[30.446697859858002,30.446697859858002],"host_mass_solar":[0.059,0.068],"host_radius_solar":[0.082,0.164],"host_temperature_k":[189.65,175.4],"semi_major_axis_km":[242348.55053399998,242348.55053399998],"orbital_period_days":[0.00003229,0.00003229]},"host_mass_solar":0.96,"inclination_deg":89.67,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":0.94,"planets_in_system":2,"discovery_facility":"Kepler","host_temperature_k":5646,"orbital_period_days":58.3620495,"transit_midpoint_bjd":2455029.555062,"equilibrium_temperature_k":446},"designations":[{"catalog":"Exoplanet","designation":"Kepler-561 b"}],"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."}