{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.675","julian_year":2026.675,"time":"2026-09-04T10:37:58.041Z","years_from_j2000":26.675,"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-99648","name":"84 τ Leo","class":"g8_iiia_yellow_giant","category":"star","object_type":"G8-IIIa yellow giant","mag":4.95,"mag_band":"V","abs_mag":-1.233,"abs_mag_band":"V","distance_ly":562.3386047637906,"distance_method":"parallax","ra_deg":171.98433,"dec_deg":2.856265,"epoch_ra_deg":172.329656,"epoch_dec_deg":2.708389,"epoch_moved_arcsec":0.539,"pm_ra_mas_yr":17.32,"pm_dec_mas_yr":-10.41,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Leo","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/hd-99648","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"wds_id":"11279+0251","companions":[{"measured":2019,"magnitude":7.47,"components":"AB","discoverer_code":"STFA 19","separation_arcsec":89.2,"position_angle_deg":181},{"measured":2019,"magnitude":9.51,"components":"AD","discoverer_code":"STFA 19","separation_arcsec":761.5,"position_angle_deg":92}],"spectral_type":"G8-IIIa","uncertainties":{"metallicity_fe_h":[0.192,0.192]},"color_index_bv":1,"luminosity_solar":271.1440008688312,"metallicity_fe_h":0.045,"radial_velocity_km_s":-9,"spectral_type_source":"SIMBAD (1989ApJS...71..245K, quality B)","surface_gravity_log_g":2.32,"surface_temperature_k":4942,"metallicity_fe_h_source":"Median of 4 spectroscopic determinations in 5 papers, compiled from the literature (PASTEL, Soubiran+ 2016); the error bar is the scatter between them","proper_motion_ra_mas_yr":17.32,"proper_motion_dec_mas_yr":-10.41,"stellar_parameters_method":"Spectroscopic determinations compiled from the literature (PASTEL, Soubiran+ 2016)"},"designations":[{"catalog":"Bayer/Flamsteed","designation":"84 Tau Leo"},{"catalog":"HD","designation":"HD 99648"},{"catalog":"HIP","designation":"HIP 55945"},{"catalog":"HR","designation":"HR 4418"}],"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."}