{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.681","julian_year":2026.681,"time":"2026-09-06T17:32:27.857Z","years_from_j2000":26.681,"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":"toi-251-b","name":"TOI-251 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":324.6006117950345,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":353.0620655,"dec_deg":-37.2558629,"epoch_ra_deg":353.421363,"epoch_dec_deg":-37.107609,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"TOI-251","semi_major_axis_km":8588413.756887,"periapsis_km":null,"mass_kg":1.898134113420134e+27,"mass_msun":0.000954599,"constellation":"Sculptor","discovered":"2021","featured":false,"url":"https://spacecatalog.org/object/toi-251-b","radius_km":17475.994000000002,"radius_kind":null,"data_quality":"The published mass and radius imply a density no material has. One of the two is likely an upper limit rather than a measurement.","description":null,"properties":{"host_star":"TOI-251","host_v_mag":9.887,"eccentricity":0,"uncertainties":{"radius_km":[1148.058,1148.058],"distance_ly":[1.4142140537797994,1.4266079961330358],"host_mass_solar":[0.009,0.013],"inclination_deg":[0.31,0.4],"host_radius_solar":[0.047,0.038],"host_temperature_k":[190,100],"semi_major_axis_km":[25431.638018999998,34407.510260999996],"orbital_period_days":[0.000029,0.000028]},"host_mass_solar":1.036,"inclination_deg":87.52,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":0.881,"planets_in_system":1,"discovery_facility":"Transiting Exoplanet Survey Satellite (TESS)","host_temperature_k":5875,"orbital_period_days":4.93777,"transit_midpoint_bjd":2458357.30548,"equilibrium_temperature_k":1041.19},"designations":[{"catalog":"Exoplanet","designation":"TOI-251 b"},{"catalog":"Host star","designation":"TOI-251"}],"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."}