{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.666","julian_year":2026.666,"time":"2026-09-01T09:18:15.215Z","years_from_j2000":26.666,"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-166309","name":"HD 166309","class":"g8iii_yellow_giant","category":"star","object_type":"G8III yellow giant","mag":7.61,"mag_band":"V","abs_mag":1.603,"abs_mag_band":"V","distance_ly":518.5315632035216,"distance_method":"parallax","ra_deg":272.81599500000004,"dec_deg":-29.639608,"epoch_ra_deg":273.244937,"epoch_dec_deg":-29.634172,"epoch_moved_arcsec":0.553,"pm_ra_mas_yr":-2.74,"pm_dec_mas_yr":-20.54,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Sagittarius","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/hd-166309","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"wds_id":"18113-2938","companions":[{"measured":2015,"magnitude":12.5,"components":null,"discoverer_code":"B   927","separation_arcsec":4.7,"position_angle_deg":212}],"spectral_type":"G8III","color_index_bv":1.055,"luminosity_solar":19.89756811090657,"radial_velocity_km_s":0,"spectral_type_source":"SIMBAD (1982MSS...C03....0H, quality C)","surface_temperature_k":4399,"proper_motion_ra_mas_yr":-2.74,"proper_motion_dec_mas_yr":-20.54,"stellar_parameters_method":"Spectroscopic determinations compiled from the literature (PASTEL, Soubiran+ 2016)"},"designations":[{"catalog":"HD","designation":"HD 166309"},{"catalog":"HIP","designation":"HIP 89116"}],"source":{"id":"hyg","name":"HYG Database v4.1","url":"https://github.com/astronexus/HYG-Database","license":"CC-BY-SA-4.0"},"updated_at":"2026-08-30T09:56:50.739Z","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."}