{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.671","julian_year":2026.671,"time":"2026-09-03T01:19:55.314Z","years_from_j2000":26.671,"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-90432","name":"42 μ Hya","class":"k4iii_orange_giant","category":"star","object_type":"K4III orange giant","mag":3.83,"mag_band":"V","abs_mag":-0.45,"abs_mag_band":"V","distance_ly":234.13950965340717,"distance_method":"parallax","ra_deg":156.52263,"dec_deg":-16.83629,"epoch_ra_deg":156.847043,"epoch_dec_deg":-16.973248,"epoch_moved_arcsec":4.038,"pm_ra_mas_yr":-128.51,"pm_dec_mas_yr":-80.06,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Hydra","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/hd-90432","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"spectral_type":"K4III","uncertainties":{"metallicity_fe_h":[0.01,0.01]},"color_index_bv":1.456,"luminosity_solar":131.82567385564073,"metallicity_fe_h":-0.12,"radial_velocity_km_s":40,"spectral_type_source":"SIMBAD (1989ApJS...71..245K, quality B)","surface_gravity_log_g":1.89,"surface_temperature_k":3979,"metallicity_fe_h_source":"Median of 2 spectroscopic determinations in 3 papers, compiled from the literature (PASTEL, Soubiran+ 2016); the error bar is the scatter between them","proper_motion_ra_mas_yr":-128.51,"proper_motion_dec_mas_yr":-80.06,"stellar_parameters_method":"Spectroscopic determinations compiled from the literature (PASTEL, Soubiran+ 2016)"},"designations":[{"catalog":"Bayer/Flamsteed","designation":"42 Mu Hya"},{"catalog":"HD","designation":"HD 90432"},{"catalog":"HIP","designation":"HIP 51069"},{"catalog":"HR","designation":"HR 4094"}],"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."}