{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.681","julian_year":2026.681,"time":"2026-09-06T21:46:47.259Z","years_from_j2000":26.681,"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-171587","name":"HD 171587","class":"g5v_yellow_main_sequence_star","category":"star","object_type":"G5V yellow main-sequence star","mag":8.52,"mag_band":"V","abs_mag":5.435,"abs_mag_band":"V","distance_ly":135.0545067285714,"distance_method":"parallax","ra_deg":279.03841500000004,"dec_deg":-10.890715,"epoch_ra_deg":279.412046,"epoch_dec_deg":-10.87044,"epoch_moved_arcsec":6.178,"pm_ra_mas_yr":126.3,"pm_dec_mas_yr":-194.08,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Scutum","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/hd-171587","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"wds_id":"18362-1053","companions":[{"measured":2005,"magnitude":null,"components":"AB","discoverer_code":"EGN  23","separation_arcsec":3.5,"position_angle_deg":140},{"measured":2005,"magnitude":15.1,"components":"AC","discoverer_code":"EGN  23","separation_arcsec":8.7,"position_angle_deg":214},{"measured":2005,"magnitude":16.1,"components":"AD","discoverer_code":"EGN  23","separation_arcsec":13.5,"position_angle_deg":233},{"measured":2005,"magnitude":null,"components":"AE","discoverer_code":"EGN  23","separation_arcsec":13.6,"position_angle_deg":203},{"measured":2005,"magnitude":null,"components":"AF","discoverer_code":"EGN  23","separation_arcsec":14.5,"position_angle_deg":154},{"measured":2005,"magnitude":null,"components":"AG","discoverer_code":"EGN  23","separation_arcsec":14.6,"position_angle_deg":213},{"measured":2005,"magnitude":null,"components":"AH","discoverer_code":"EGN  23","separation_arcsec":16.4,"position_angle_deg":145},{"measured":2005,"magnitude":null,"components":"AJ","discoverer_code":"EGN  23","separation_arcsec":18.4,"position_angle_deg":210},{"measured":2015,"magnitude":null,"components":"AK","discoverer_code":"EGN  23","separation_arcsec":19.1,"position_angle_deg":171},{"measured":2015,"magnitude":null,"components":"AI","discoverer_code":"EGN  23","separation_arcsec":19.3,"position_angle_deg":307},{"measured":2005,"magnitude":null,"components":"AL","discoverer_code":"EGN  23","separation_arcsec":21.1,"position_angle_deg":221},{"measured":2005,"magnitude":null,"components":"AM","discoverer_code":"EGN  23","separation_arcsec":21.8,"position_angle_deg":235}],"radius_solar":0.767,"spectral_type":"G5V","uncertainties":{"metallicity_fe_h":[0.02,0.02]},"color_index_bv":0.691,"luminosity_solar":0.5834451042737447,"metallicity_fe_h":-0.62,"radial_velocity_km_s":0,"spectral_type_source":"SIMBAD (1999MSS...C05....0H, quality C)","surface_gravity_log_g":4.532,"surface_temperature_k":5372,"metallicity_fe_h_source":"Median of 2 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":126.3,"proper_motion_dec_mas_yr":-194.08,"stellar_parameters_method":"Gaia DR3 model fit (GSP-Phot, FLAME; RUWE ≤ 1.4)","bolometric_luminosity_solar":0.4375},"designations":[{"catalog":"HD","designation":"HD 171587"},{"catalog":"HIP","designation":"HIP 91187"}],"source":{"id":"hyg","name":"HYG Database v4.1","url":"https://github.com/astronexus/HYG-Database","license":"CC-BY-SA-4.0"},"updated_at":"2026-09-02T19:50:56.720Z","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."}