{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.674","julian_year":2026.674,"time":"2026-09-04T06:23:28.690Z","years_from_j2000":26.674,"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-170958","name":"HD 170958","class":"g8iv_v_yellow_subgiant","category":"star","object_type":"G8IV/V yellow subgiant","mag":9.52,"mag_band":"V","abs_mag":5.861,"abs_mag_band":"V","distance_ly":175.92027007459075,"distance_method":"parallax","ra_deg":278.35362,"dec_deg":-29.866831,"epoch_ra_deg":278.783096,"epoch_dec_deg":-29.847111,"epoch_moved_arcsec":1.468,"pm_ra_mas_yr":38.73,"pm_dec_mas_yr":-39.09,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Sagittarius","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/hd-170958","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"age_years":4746828000,"mass_solar":0.912,"radius_solar":0.869,"spectral_type":"G8IV/V","uncertainties":{"metallicity_fe_h":[0.06,0.06]},"color_index_bv":0.745,"luminosity_solar":0.39409416073228565,"metallicity_fe_h":-0.04,"radial_velocity_km_s":0,"spectral_type_source":"SIMBAD (1982MSS...C03....0H, quality D)","surface_gravity_log_g":4.476,"surface_temperature_k":5419,"metallicity_fe_h_source":"One spectroscopic determination, compiled from the literature (PASTEL, Soubiran+ 2016)","proper_motion_ra_mas_yr":38.73,"proper_motion_dec_mas_yr":-39.09,"stellar_parameters_method":"Gaia DR3 model fit (GSP-Phot, FLAME; RUWE ≤ 1.4)","bolometric_luminosity_solar":0.5828},"designations":[{"catalog":"HD","designation":"HD 170958"},{"catalog":"HIP","designation":"HIP 90973"}],"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."}