{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.670","julian_year":2026.67,"time":"2026-09-02T13:07:48.537Z","years_from_j2000":26.67,"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-28447","name":"HD 28447","class":"g5v_yellow_main_sequence_star","category":"star","object_type":"G5V yellow main-sequence star","mag":6.51,"mag_band":"V","abs_mag":3.579,"abs_mag_band":"V","distance_ly":125.78351169197296,"distance_method":"parallax","ra_deg":67.58352000000001,"dec_deg":28.131889,"epoch_ra_deg":68.002319,"epoch_dec_deg":28.190871,"epoch_moved_arcsec":3.928,"pm_ra_mas_yr":139.28,"pm_dec_mas_yr":47.91,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Taurus","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/hd-28447","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"age_years":6231513000,"mass_solar":1.17,"radius_solar":2.107,"spectral_type":"G5V","uncertainties":{"metallicity_fe_h":[0.036,0.036]},"color_index_bv":0.722,"luminosity_solar":3.224036871918187,"metallicity_fe_h":-0.085,"radial_velocity_km_s":22.9,"spectral_type_source":"SIMBAD (1954ArA.....1..425A, quality E)","surface_gravity_log_g":4.027,"surface_temperature_k":5445,"metallicity_fe_h_source":"Median of 6 spectroscopic determinations in 8 papers, compiled from the literature (PASTEL, Soubiran+ 2016); the error bar is the scatter between them","proper_motion_ra_mas_yr":139.28,"proper_motion_dec_mas_yr":47.91,"stellar_parameters_method":"Gaia DR3 model fit (GSP-Phot, FLAME; RUWE ≤ 1.4)","bolometric_luminosity_solar":3.5339},"designations":[{"catalog":"HD","designation":"HD 28447"},{"catalog":"HIP","designation":"HIP 21010"}],"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."}