{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.664","julian_year":2026.664,"time":"2026-08-31T13:09:33.650Z","years_from_j2000":26.664,"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":"alhena","name":"Alhena","class":"a1_5iv_white_subgiant","category":"star","object_type":"A1.5IV+ white subgiant","mag":1.93,"mag_band":"V","abs_mag":-0.696,"abs_mag_band":"V","distance_ly":109.30185145681276,"distance_method":"parallax","ra_deg":99.42792,"dec_deg":16.399252,"epoch_ra_deg":99.81532,"epoch_dec_deg":16.376067,"epoch_moved_arcsec":1.785,"pm_ra_mas_yr":-2.04,"pm_dec_mas_yr":-66.92,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Gemini","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/alhena","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"wds_id":"06377+1624","companions":[{"measured":2024,"magnitude":7.5,"components":"Aa,Ab","discoverer_code":"OCC9011","separation_arcsec":0.4,"position_angle_deg":260},{"measured":2009,"magnitude":13,"components":"AB","discoverer_code":"BUP  90","separation_arcsec":140.5,"position_angle_deg":296},{"measured":2009,"magnitude":12.3,"components":"AC","discoverer_code":"BUP  90","separation_arcsec":148.1,"position_angle_deg":335}],"spectral_type":"A1.5IV+","uncertainties":{"metallicity_fe_h":[0.081,0.081]},"color_index_bv":0.001,"luminosity_solar":165.34840121711517,"metallicity_fe_h":-0.08,"radial_velocity_km_s":-13,"spectral_type_source":"SIMBAD (2003AJ....126.2048G, quality C)","surface_gravity_log_g":3.6,"surface_temperature_k":9260,"metallicity_fe_h_source":"Median of 5 spectroscopic determinations in 9 papers, compiled from the literature (PASTEL, Soubiran+ 2016); the error bar is the scatter between them","proper_motion_ra_mas_yr":-2.04,"proper_motion_dec_mas_yr":-66.92,"stellar_parameters_method":"Spectroscopic determinations compiled from the literature (PASTEL, Soubiran+ 2016)"},"designations":[{"catalog":"Bayer/Flamsteed","designation":"24 Gamma Gem"},{"catalog":"Common name","designation":"Alhena"},{"catalog":"HD","designation":"HD 47105"},{"catalog":"HIP","designation":"HIP 31681"},{"catalog":"HR","designation":"HR 2421"}],"source":{"id":"hyg","name":"HYG Database v4.1","url":"https://github.com/astronexus/HYG-Database","license":"CC-BY-SA-4.0"},"updated_at":"2026-08-30T09:56:50.739Z","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."}