{"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":"2026-09-03T09:17:38.409Z","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-209459","name":"21 Peg","class":"b9_5v_blue_white_main_sequence_star","category":"star","object_type":"B9.5V blue-white main-sequence star","mag":5.83,"mag_band":"V","abs_mag":-0.598,"abs_mag_band":"V","distance_ly":629.6455394949286,"distance_method":"parallax","ra_deg":330.829305,"dec_deg":11.386552,"epoch_ra_deg":331.158386,"epoch_dec_deg":11.516164,"epoch_moved_arcsec":0.448,"pm_ra_mas_yr":16.71,"pm_dec_mas_yr":-1.63,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Pegasus","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/hd-209459","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"age_years":257934660,"mass_solar":3.381,"radius_solar":5.182,"spectral_type":"B9.5V","uncertainties":{"metallicity_fe_h":[0.171,0.171]},"color_index_bv":-0.05,"luminosity_solar":151.0775731924994,"metallicity_fe_h":-0.05,"radial_velocity_km_s":0.8,"spectral_type_source":"SIMBAD (1999A&AS..137..451G, quality C)","surface_gravity_log_g":3.513,"surface_temperature_k":10107,"metallicity_fe_h_source":"Median of 3 spectroscopic determinations in 4 papers, compiled from the literature (PASTEL, Soubiran+ 2016); the error bar is the scatter between them","proper_motion_ra_mas_yr":16.71,"proper_motion_dec_mas_yr":-1.63,"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":231.6158},"designations":[{"catalog":"Bayer/Flamsteed","designation":"21 Peg"},{"catalog":"HD","designation":"HD 209459"},{"catalog":"HIP","designation":"HIP 108875"},{"catalog":"HR","designation":"HR 8404"}],"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."}