{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.676","julian_year":2026.676,"time":"2026-09-04T23:02:25.111Z","years_from_j2000":26.676,"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-27819","name":"64 δ² Tau","class":"a2vs_white_main_sequence_star","category":"star","object_type":"A2Vs white main-sequence star","mag":4.8,"mag_band":"V","abs_mag":1.328,"abs_mag_band":"V","distance_ly":161.38380647613323,"distance_method":"parallax","ra_deg":66.023985,"dec_deg":17.44413,"epoch_ra_deg":66.411747,"epoch_dec_deg":17.506271,"epoch_moved_arcsec":3.067,"pm_ra_mas_yr":109.99,"pm_dec_mas_yr":-33.47,"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-27819","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"wds_id":"04241+1727","companions":[{"measured":2007,"magnitude":9.64,"components":"AC","discoverer_code":"DRS  37","separation_arcsec":10,"position_angle_deg":85},{"measured":2015,"magnitude":14.65,"components":"AB","discoverer_code":"BUP  56","separation_arcsec":147.2,"position_angle_deg":249}],"spectral_type":"A2Vs","uncertainties":{"metallicity_fe_h":[0.143,0.143]},"color_index_bv":0.154,"luminosity_solar":25.63303319865898,"metallicity_fe_h":0.145,"radial_velocity_km_s":39,"spectral_type_source":"SIMBAD (2001A&A...373..625P, quality C)","surface_gravity_log_g":4,"surface_temperature_k":8174,"metallicity_fe_h_source":"Median of 4 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":109.99,"proper_motion_dec_mas_yr":-33.47,"stellar_parameters_method":"Spectroscopic determinations compiled from the literature (PASTEL, Soubiran+ 2016)"},"designations":[{"catalog":"Bayer/Flamsteed","designation":"64 Delta2 Tau"},{"catalog":"HD","designation":"HD 27819"},{"catalog":"HIP","designation":"HIP 20542"},{"catalog":"HR","designation":"HR 1380"}],"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."}