{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.684","julian_year":2026.684,"time":"2026-09-08T00:13:18.359Z","years_from_j2000":26.684,"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":"mxb-1658-298-b","name":"MXB 1658-298 b","class":"gas_giant","category":"exoplanet","object_type":"Gas giant","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":null,"distance_method":null,"ra_deg":255.5272522,"dec_deg":-29.9455833,"epoch_ra_deg":255.954788,"epoch_dec_deg":-29.984664,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"MXB 1658-298","semi_major_axis_km":241301365.43909997,"periapsis_km":null,"mass_kg":4.498577848805718e+28,"mass_msun":0.022624,"constellation":"Ophiuchus","discovered":"2017","featured":false,"url":"https://spacecatalog.org/object/mxb-1658-298-b","radius_km":76537.20000000001,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"MXB 1658-298","uncertainties":{"mass_kg":[6.07402916294443e+27,6.07402916294443e+27],"semi_major_axis_km":[16455765.776999999,16455765.776999999]},"host_mass_solar":1.98,"stars_in_system":2,"discovery_method":"Eclipse Timing Variations","planets_in_system":1,"discovery_facility":"Multiple Observatories","orbital_period_days":760},"designations":[{"catalog":"Exoplanet","designation":"MXB 1658-298 b"},{"catalog":"Host star","designation":"MXB 1658-298"}],"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."}