{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.809","julian_year":2026.809,"time":"2026-10-23T08:51:28.782Z","years_from_j2000":26.809,"frame":"date","applied":"Proper motion, then precession and nutation. The catalogued position is carried along the great circle the object's own published motion puts it on, at a constant velocity, from the epoch that position was measured at, 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. The motion runs from position_epoch_jyear where the upstream publishes one — a timed pulsar's position belongs to the year it was timed — and from J2000 where it does not. 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":"alcyone","name":"Alcyone","class":"b7iii_blue_white_giant","category":"star","object_type":"B7III blue-white giant","mag":2.85,"mag_band":"V","abs_mag":-2.61,"abs_mag_band":"V","distance_ly":403.1599415574002,"distance_method":"parallax","ra_deg":56.87115,"dec_deg":24.105137,"epoch_ra_deg":57.272779,"epoch_dec_deg":24.188287,"epoch_moved_arcsec":1.267,"pm_ra_mas_yr":19.35,"pm_dec_mas_yr":-43.11,"position_epoch_jyear":null,"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/alcyone","source":{"id":"hyg","name":"HYG Database v4.1","url":"https://github.com/astronexus/HYG-Database","license":"CC-BY-SA-4.0","attribution":"HYG Database v4.1, Astronexus (github.com/astronexus/HYG-Database). Fields derived from it stay under CC BY-SA 4.0.","commercial_use":"allowed"},"radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"wds_id":"03475+2406","companions":[{"measured":2016,"magnitude":15,"components":"AE","discoverer_code":"HL   23","separation_arcsec":78.4,"position_angle_deg":232},{"measured":2016,"magnitude":6.27,"components":"AB","discoverer_code":"STFA  8","separation_arcsec":117.6,"position_angle_deg":291},{"measured":2016,"magnitude":13.02,"components":"AF","discoverer_code":"HL   23","separation_arcsec":144.5,"position_angle_deg":232},{"measured":2016,"magnitude":8.22,"components":"AC","discoverer_code":"STFA  8","separation_arcsec":182,"position_angle_deg":313},{"measured":2016,"magnitude":8.73,"components":"AD","discoverer_code":"STFA  8","separation_arcsec":191.8,"position_angle_deg":297},{"measured":2016,"magnitude":11.84,"components":"AG","discoverer_code":"HL   23","separation_arcsec":200,"position_angle_deg":54},{"measured":2016,"magnitude":11.72,"components":"AH","discoverer_code":"HL   23","separation_arcsec":222.8,"position_angle_deg":44}],"wikidata_id":"Q13425","also_known_as":["Eta Tauri","η Tau","η Tauri"],"spectral_type":"B7III","color_index_bv":-0.086,"luminosity_solar":963.8290236239706,"wikipedia_article":"Alcyone (star)","radial_velocity_km_s":10,"spectral_type_source":"SIMBAD (quality C)","surface_gravity_log_g":4,"surface_temperature_k":13490,"proper_motion_ra_mas_yr":19.35,"proper_motion_dec_mas_yr":-43.11,"stellar_parameters_method":"Spectroscopic determinations compiled from the literature (PASTEL, Soubiran+ 2016)"},"designations":[{"catalog":"Bayer/Flamsteed","designation":"25 Eta Tau"},{"catalog":"Common name","designation":"Alcyone"},{"catalog":"HD","designation":"HD 23630"},{"catalog":"HIP","designation":"HIP 17702"},{"catalog":"HR","designation":"HR 1165"},{"catalog":"IRAS","designation":"IRAS 03445+2357"}],"updated_at":"2026-10-01T09:42:28.932Z","citation":{"plain":"SpaceCatalog. Alcyone [catalogue entry]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/alcyone","bibtex":"@misc{spacecatalog_alcyone,\n  author       = {{SpaceCatalog}},\n  title        = {{Alcyone}},\n  howpublished = {SpaceCatalog, data release DR1 (2026-08-21)},\n  year         = {2026},\n  url          = {https://spacecatalog.org/object/alcyone},\n  note         = {Catalogue entry, data release DR1 (2026-08-21). Values from HYG Database v4.1.}\n}","url":"https://spacecatalog.org/object/alcyone","release":"DR1","doi":null},"references":[],"attribution":"Data from SpaceCatalog.org. Each record names its upstream in `source`, with that producer's terms in `source.license`, the acknowledgement it asks for in `source.attribution`, and whether its terms allow commercial use in `source.commercial_use`; those terms govern the record, and citing SpaceCatalog does not discharge them."}