{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.687","julian_year":2026.687,"time":"2026-09-09T01:49:54.258Z","years_from_j2000":26.687,"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":"kmt-2021-blg-1253l-b","name":"KMT-2021-BLG-1253L 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":21656.78348039176,"distance_method":"NASA Exoplanet Archive sy_dist (Ryu+ 2022, 2022AJ....164..180R)","ra_deg":267.6172083,"dec_deg":-29.2792806,"epoch_ra_deg":268.045307,"epoch_dec_deg":-29.287262,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"KMT-2021-BLG-1253L","semi_major_axis_km":227388763.464,"periapsis_km":null,"mass_kg":1.1376979788142577e+26,"mass_msun":0.0000572165,"constellation":"Sagittarius","discovered":"2022","featured":false,"url":"https://spacecatalog.org/object/kmt-2021-blg-1253l-b","radius_km":29275.479,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"KMT-2021-BLG-1253L","uncertainties":{"mass_kg":[6.055778217940459e+25,1.2195166786029997e+26],"distance_ly":[4240.032910317665,3359.410690482457],"host_mass_solar":[0.13,0.26],"semi_major_axis_km":[61335126.98699999,85270786.29899998]},"host_mass_solar":0.24,"stars_in_system":1,"discovery_method":"Microlensing","planets_in_system":1,"discovery_facility":"KMTNet"},"designations":[{"catalog":"Exoplanet","designation":"KMT-2021-BLG-1253L b"},{"catalog":"Host star","designation":"KMT-2021-BLG-1253L"}],"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."}