{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.685","julian_year":2026.685,"time":"2026-09-08T08:28:32.146Z","years_from_j2000":26.685,"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":"hd-4917-b","name":"HD 4917 b","class":"gas_giant","category":"exoplanet","object_type":"Gas giant","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":666.2624637084319,"distance_method":"NASA Exoplanet Archive sy_dist (TICv8, 2019AJ....158..138S)","ra_deg":12.7762624,"dec_deg":-12.9276648,"epoch_ra_deg":13.113419,"epoch_dec_deg":-12.781354,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":"HD 4917","semi_major_axis_km":174580715.1069,"periapsis_km":null,"mass_kg":3.0654865931735163e+27,"mass_msun":0.00154168,"constellation":"Cetus","discovered":"2018","featured":false,"url":"https://spacecatalog.org/object/hd-4917-b","radius_km":86104.35,"radius_kind":null,"data_quality":null,"description":null,"properties":{"host_star":"HD 4917","host_v_mag":8.03,"eccentricity":0.066,"uncertainties":{"mass_kg":[1.7462833843465232e+26,1.7462833843465232e+26],"distance_ly":[8.070739566600816,8.070739566600816],"eccentricity":[0.041,0.041],"semi_major_axis_km":[9723861.5955,9723861.5955],"orbital_period_days":[1.7,1.7],"argument_of_periastron_deg":[34,34]},"host_mass_solar":1.32,"stars_in_system":1,"discovery_method":"Radial Velocity","host_radius_solar":5.01,"planets_in_system":1,"discovery_facility":"W. M. Keck Observatory","host_spectral_type":"K0 III/IV","host_temperature_k":4802,"orbital_period_days":400.5,"periastron_epoch_bjd":2439788,"equilibrium_temperature_k":479.78,"argument_of_periastron_deg":313},"designations":[{"catalog":"Exoplanet","designation":"HD 4917 b"},{"catalog":"Host star","designation":"HD 4917"}],"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."}