{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.679","julian_year":2026.679,"time":"2026-09-06T00:23:28.922Z","years_from_j2000":26.679,"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":"ngts-18-b","name":"NGTS-18 b","class":"gas_giant","category":"exoplanet","object_type":"Gas giant","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":3575.2935968931697,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":180.5462193,"dec_deg":-35.5486091,"epoch_ra_deg":180.890102,"epoch_dec_deg":-35.698173,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"NGTS-18","semi_major_axis_km":6701984.60736,"periapsis_km":null,"mass_kg":7.763329612825822e+26,"mass_msun":0.000390429,"constellation":"Hydra","discovered":"2021","featured":false,"url":"https://spacecatalog.org/object/ngts-18-b","radius_km":86505.31978036501,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"NGTS-18","host_v_mag":14.588,"eccentricity":0,"uncertainties":{"mass_kg":[1.1958184977870122e+26,1.5374809259821088e+26],"radius_km":[12868.559989993002,12868.559989993002],"distance_ly":[130.5277823622407,140.60601443368807],"host_mass_solar":[0.025,0.03],"host_radius_solar":[0.209,0.209],"host_temperature_k":[150,150],"semi_major_axis_km":[1017265.5207599999,1017265.5207599999],"orbital_period_days":[0.00001,0.00001]},"host_mass_solar":1.003,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":1.392,"planets_in_system":1,"discovery_facility":"Next-Generation Transit Survey (NGTS)","host_spectral_type":"G5 V","host_temperature_k":5610,"orbital_period_days":3.05125,"transit_midpoint_bjd":2458564.4506,"equilibrium_temperature_k":1381},"designations":[{"catalog":"Exoplanet","designation":"NGTS-18 b"},{"catalog":"Host star","designation":"NGTS-18"}],"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."}