{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.673","julian_year":2026.673,"time":"2026-09-03T22:28:32.525Z","years_from_j2000":26.673,"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-3821","name":"HD 3821","class":"g1v_yellow_main_sequence_star","category":"star","object_type":"G1V yellow main-sequence star","mag":7.02,"mag_band":"V","abs_mag":4.903,"abs_mag_band":"V","distance_ly":86.44481250642339,"distance_method":"parallax","ra_deg":10.19784,"dec_deg":-7.232606,"epoch_ra_deg":10.538818,"epoch_dec_deg":-7.085814,"epoch_moved_arcsec":2.443,"pm_ra_mas_yr":0.64,"pm_dec_mas_yr":-91.59,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Cetus","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/hd-3821","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"wds_id":"00408-0714","age_years":5705565000,"companions":[{"measured":2017,"magnitude":9.98,"components":null,"discoverer_code":"STF  49","separation_arcsec":8.6,"position_angle_deg":320}],"mass_solar":0.972,"radius_solar":0.988,"spectral_type":"G1V","uncertainties":{"metallicity_fe_h":[0.008,0.008]},"color_index_bv":0.62,"luminosity_solar":0.952357486191919,"metallicity_fe_h":-0.087,"radial_velocity_km_s":7.6,"spectral_type_source":"SIMBAD (2006A&A...460..695T, quality C)","surface_gravity_log_g":4.407,"surface_temperature_k":5692,"metallicity_fe_h_source":"One spectroscopic determination, compiled from the literature (PASTEL, Soubiran+ 2016)","proper_motion_ra_mas_yr":0.64,"proper_motion_dec_mas_yr":-91.59,"stellar_parameters_method":"Gaia DR3 model fit (GSP-Phot, FLAME; RUWE ≤ 1.4)","bolometric_luminosity_solar":0.9158},"designations":[{"catalog":"HD","designation":"HD 3821"},{"catalog":"HIP","designation":"HIP 3203"}],"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."}