{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.672","julian_year":2026.672,"time":"2026-09-03T14:26:22.294Z","years_from_j2000":26.672,"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-15558","name":"HD 15558","class":"o4_5iii_f_blue_giant","category":"star","object_type":"O4.5III(f) blue giant","mag":7.91,"mag_band":"V","abs_mag":null,"abs_mag_band":null,"distance_ly":null,"distance_method":null,"ra_deg":38.177234999999996,"dec_deg":61.455991,"epoch_ra_deg":38.689212,"epoch_dec_deg":61.574509,"epoch_moved_arcsec":0.05,"pm_ra_mas_yr":-1.17,"pm_dec_mas_yr":-1.48,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Cassiopeia","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/hd-15558","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"wds_id":"02327+6127","companions":[{"measured":2001,"magnitude":11.7,"components":"AJ","discoverer_code":"TRN  11","separation_arcsec":3,"position_angle_deg":221},{"measured":2015,"magnitude":14,"components":"AF","discoverer_code":"TRN  11","separation_arcsec":4.6,"position_angle_deg":263},{"measured":2001,"magnitude":19,"components":"AH","discoverer_code":"TRN  11","separation_arcsec":5.8,"position_angle_deg":211},{"measured":2015,"magnitude":10.13,"components":"AB","discoverer_code":"STI 368","separation_arcsec":9.9,"position_angle_deg":97},{"measured":2015,"magnitude":15.7,"components":"AI","discoverer_code":"MZA   9","separation_arcsec":10.6,"position_angle_deg":53},{"measured":2015,"magnitude":13.9,"components":"AK","discoverer_code":"SS    3","separation_arcsec":12.2,"position_angle_deg":263},{"measured":2015,"magnitude":13.08,"components":"AG","discoverer_code":"STI 367","separation_arcsec":24.8,"position_angle_deg":342},{"measured":2015,"magnitude":11.21,"components":"AD","discoverer_code":"WAL  17","separation_arcsec":40.2,"position_angle_deg":342},{"measured":2015,"magnitude":13.1,"components":"AC","discoverer_code":"WAL  17","separation_arcsec":43.3,"position_angle_deg":35},{"measured":2015,"magnitude":9.58,"components":"AE","discoverer_code":"WAL  17","separation_arcsec":78.2,"position_angle_deg":325}],"spectral_type":"O4.5III(f)","color_index_bv":0.43,"radial_velocity_km_s":-41.9,"spectral_type_source":"SIMBAD (2014ApJS..211...10S, quality C)","surface_gravity_log_g":3.83,"surface_temperature_k":43750,"proper_motion_ra_mas_yr":-1.17,"proper_motion_dec_mas_yr":-1.48,"stellar_parameters_method":"Spectroscopic determinations compiled from the literature (PASTEL, Soubiran+ 2016)"},"designations":[{"catalog":"HD","designation":"HD 15558"},{"catalog":"HIP","designation":"HIP 11832"}],"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."}