{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.831","julian_year":2026.831,"time":"2026-10-31T13:20:12.414Z","years_from_j2000":26.831,"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":"hd-57281","name":"HD 57281","class":"b3vk_blue_white_main_sequence_star","category":"star","object_type":"B3Vk blue-white main-sequence star","mag":8.97,"mag_band":"V","abs_mag":4.719,"abs_mag_band":"V","distance_ly":230.98883904466345,"distance_method":"parallax","ra_deg":109.906245,"dec_deg":-24.024367,"epoch_ra_deg":110.18883,"epoch_dec_deg":-24.073857,"epoch_moved_arcsec":0.235,"pm_ra_mas_yr":7.59,"pm_dec_mas_yr":4.35,"position_epoch_jyear":null,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Canis Major","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/hd-57281","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":"07196-2401","companions":[{"measured":2016,"magnitude":11.1,"components":"AC","discoverer_code":"ARA2043","separation_arcsec":8.6,"position_angle_deg":5},{"measured":2015,"magnitude":10.22,"components":"AB","discoverer_code":"ARA2043","separation_arcsec":9.7,"position_angle_deg":290},{"measured":2015,"magnitude":12.24,"components":"AE","discoverer_code":"ABH  63","separation_arcsec":100.3,"position_angle_deg":83},{"measured":2015,"magnitude":14.1,"components":"AG","discoverer_code":"ABH  63","separation_arcsec":116.8,"position_angle_deg":115},{"measured":2015,"magnitude":12.14,"components":"AD","discoverer_code":"ABH  63","separation_arcsec":121.1,"position_angle_deg":121},{"measured":2015,"magnitude":12.53,"components":"AF","discoverer_code":"ABH  63","separation_arcsec":130.4,"position_angle_deg":75}],"mass_solar":4.968,"radius_solar":5.896,"spectral_type":"B3Vk","color_index_bv":-0.06,"luminosity_solar":1.1282361216489918,"variable_mag_max":8.934,"variable_mag_min":9.044,"radial_velocity_km_s":0,"spectral_type_source":"SIMBAD (1978AJ.....83..172R, quality C)","surface_gravity_log_g":3.675,"surface_temperature_k":15789,"proper_motion_ra_mas_yr":7.59,"proper_motion_dec_mas_yr":4.35,"stellar_parameters_method":"Gaia DR3 model fit (GSP-Phot, FLAME; RUWE ≤ 1.4) — low confidence: above 7,500 K GSP-Phot's temperature and extinction are degenerate","bolometric_luminosity_solar":767.2576},"designations":[{"catalog":"HD","designation":"HD 57281"},{"catalog":"HIP","designation":"HIP 35503"}],"updated_at":"2026-10-01T09:42:28.932Z","citation":{"plain":"SpaceCatalog. HD 57281 [catalogue entry]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/hd-57281","bibtex":"@misc{spacecatalog_hd-57281,\n  author       = {{SpaceCatalog}},\n  title        = {{HD 57281}},\n  howpublished = {SpaceCatalog, data release DR1 (2026-08-21)},\n  year         = {2026},\n  url          = {https://spacecatalog.org/object/hd-57281},\n  note         = {Catalogue entry, data release DR1 (2026-08-21). Values from HYG Database v4.1.}\n}","url":"https://spacecatalog.org/object/hd-57281","release":"DR1","doi":null},"references":[{"bibcode":"1978AJ.....83..172R","ads_url":"https://ui.adsabs.harvard.edu/abs/1978AJ.....83..172R/abstract","quantity":"properties.spectral_type_source"}],"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."}