{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.669","julian_year":2026.669,"time":"2026-09-02T09:17:16.256Z","years_from_j2000":26.669,"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":"hat-p-2-b","name":"HAT-P-2 b","class":"gas_giant","category":"exoplanet","object_type":"Gas giant","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":416.7430500637917,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":245.1514324,"dec_deg":41.0479601,"epoch_ra_deg":245.378201,"epoch_dec_deg":40.983322,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"HAT-P-2","semi_major_axis_km":10193598.909498,"periapsis_km":null,"mass_kg":1.7121083889805622e+28,"mass_msun":0.00861044,"constellation":"Hercules","discovered":"2007","featured":false,"url":"https://spacecatalog.org/object/hat-p-2-b","radius_km":67989.00887789999,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"HAT-P-2","host_v_mag":8.72,"eccentricity":0.5172,"uncertainties":{"mass_kg":[1.8981245997567207e+26,1.8981245997567207e+26],"radius_km":[3789.0825137,2788.1927931],"distance_ly":[1.3796414777418247,1.3861646052961596],"eccentricity":[0.0019,0.0019],"host_mass_solar":[0.03,0.03],"inclination_deg":[0.26,0.26],"host_radius_solar":[0.09,0.09],"semi_major_axis_km":[76294.914057,76294.914057],"orbital_period_days":[0.0000036,0.0000036],"argument_of_periastron_deg":[0.2,0.2]},"host_mass_solar":1.33,"inclination_deg":86.16,"stars_in_system":1,"discovery_method":"Transit","host_radius_solar":1.39,"planets_in_system":2,"discovery_facility":"HATNet","host_spectral_type":"F8","host_temperature_k":6380,"orbital_period_days":5.6335158,"periastron_epoch_bjd":2463982.4915,"transit_midpoint_bjd":2458657.66292,"equilibrium_temperature_k":1540,"argument_of_periastron_deg":188.01},"designations":[{"catalog":"Exoplanet","designation":"HAT-P-2 b"},{"catalog":"Host star","designation":"HAT-P-2"}],"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":"2026-09-01T22:58:55.274Z","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."}