{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.676","julian_year":2026.676,"time":"2026-09-04T19:07:18.505Z","years_from_j2000":26.676,"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-125451","name":"18 Boo","class":"f3v_yellow_white_main_sequence_star","category":"star","object_type":"F3V yellow-white main-sequence star","mag":5.41,"mag_band":"V","abs_mag":3.327,"abs_mag_band":"V","distance_ly":85.11376832896136,"distance_method":"parallax","ra_deg":214.81781999999998,"dec_deg":13.004299,"epoch_ra_deg":215.143472,"epoch_dec_deg":12.880242,"epoch_moved_arcsec":2.953,"pm_ra_mas_yr":105.91,"pm_dec_mas_yr":-32.22,"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-125451","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"wds_id":"14193+1300","age_years":2083495400,"companions":[{"measured":2023,"magnitude":10.84,"components":null,"discoverer_code":"ENG  51","separation_arcsec":164.6,"position_angle_deg":221}],"mass_solar":1.333,"radius_solar":1.517,"spectral_type":"F3V","color_index_bv":0.385,"luminosity_solar":4.066305463404283,"metallicity_fe_h":-0.02,"radial_velocity_km_s":-3,"spectral_type_source":"SIMBAD (2003AJ....126.2048G, quality C)","surface_gravity_log_g":4.069,"surface_temperature_k":6595,"metallicity_fe_h_source":"One spectroscopic determination, compiled from the literature (PASTEL, Soubiran+ 2016)","proper_motion_ra_mas_yr":105.91,"proper_motion_dec_mas_yr":-32.22,"stellar_parameters_method":"Gaia DR3 model fit (GSP-Phot, FLAME; RUWE ≤ 1.4)","bolometric_luminosity_solar":3.9717},"designations":[{"catalog":"Bayer/Flamsteed","designation":"18 Boo"},{"catalog":"Gliese","designation":"GJ 3841"},{"catalog":"HD","designation":"HD 125451"},{"catalog":"HIP","designation":"HIP 69989"},{"catalog":"HR","designation":"HR 5365"}],"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."}