{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.668","julian_year":2026.668,"time":"2026-09-02T00:15:22.482Z","years_from_j2000":26.668,"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-139641","name":"54 φ Boo","class":"g7iii_ivfe_2_yellow_giant","category":"star","object_type":"G7III-IVFe-2 yellow giant","mag":5.25,"mag_band":"V","abs_mag":1.669,"abs_mag_band":"V","distance_ly":169.69622791862216,"distance_method":"parallax","ra_deg":234.456615,"dec_deg":40.353433,"epoch_ra_deg":234.699004,"epoch_dec_deg":40.265361,"epoch_moved_arcsec":2.263,"pm_ra_mas_yr":60.45,"pm_dec_mas_yr":59.57,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Boötes","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/hd-139641","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"spectral_type":"G7III-IVFe-2","uncertainties":{"metallicity_fe_h":[0.306,0.306]},"color_index_bv":0.886,"luminosity_solar":18.72405895986799,"metallicity_fe_h":-0.53,"radial_velocity_km_s":-10,"spectral_type_source":"SIMBAD (1989ApJS...71..245K, quality B)","surface_gravity_log_g":2.99,"surface_temperature_k":4900,"metallicity_fe_h_source":"Median of 3 spectroscopic determinations in 4 papers, compiled from the literature (PASTEL, Soubiran+ 2016); the error bar is the scatter between them","proper_motion_ra_mas_yr":60.45,"proper_motion_dec_mas_yr":59.57,"stellar_parameters_method":"Spectroscopic determinations compiled from the literature (PASTEL, Soubiran+ 2016)"},"designations":[{"catalog":"Bayer/Flamsteed","designation":"54 Phi Boo"},{"catalog":"HD","designation":"HD 139641"},{"catalog":"HIP","designation":"HIP 76534"},{"catalog":"HR","designation":"HR 5823"}],"source":{"id":"hyg","name":"HYG Database v4.1","url":"https://github.com/astronexus/HYG-Database","license":"CC-BY-SA-4.0"},"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."}