{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.668","julian_year":2026.668,"time":"2026-09-01T19:36:21.611Z","years_from_j2000":26.668,"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-123","name":"V640 Cas","class":"g3v_g8v_yellow_main_sequence_star","category":"star","object_type":"G3V+G8V yellow main-sequence star","mag":5.98,"mag_band":"V","abs_mag":4.32,"abs_mag_band":"V","distance_ly":70.050888336869,"distance_method":"parallax","ra_deg":1.56534,"dec_deg":58.436733,"epoch_ra_deg":1.916479,"epoch_dec_deg":58.586331,"epoch_moved_arcsec":6.613,"pm_ra_mas_yr":247.36,"pm_dec_mas_yr":17.77,"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-123","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"wds_id":"00063+5826","companions":[{"measured":2021,"magnitude":7.32,"components":null,"discoverer_code":"STF3062","separation_arcsec":1.5,"position_angle_deg":8}],"spectral_type":"G3V+G8V","uncertainties":{"metallicity_fe_h":[0.01,0.01]},"color_index_bv":0.687,"luminosity_solar":1.6292960326397214,"metallicity_fe_h":0.09,"variability_type":"CST:","variable_mag_max":5.964,"variable_mag_min":5.994,"variability_class":"Not variable (GCVS)","radial_velocity_km_s":-11.6,"spectral_type_source":"SIMBAD (1935ApJ....81..187A, quality C)","variable_designation":"V640 Cas","surface_gravity_log_g":4.66,"surface_temperature_k":5717,"metallicity_fe_h_source":"One spectroscopic determination, compiled from the literature (PASTEL, Soubiran+ 2016)","proper_motion_ra_mas_yr":247.36,"proper_motion_dec_mas_yr":17.77,"stellar_parameters_method":"Spectroscopic determinations compiled from the literature (PASTEL, Soubiran+ 2016)"},"designations":[{"catalog":"Gliese","designation":"Gl 4.1A"},{"catalog":"HD","designation":"HD 123"},{"catalog":"HIP","designation":"HIP 518"},{"catalog":"HR","designation":"HR 5"},{"catalog":"Variable star","designation":"V640 Cas"}],"source":{"id":"hyg","name":"HYG Database v4.1","url":"https://github.com/astronexus/HYG-Database","license":"CC-BY-SA-4.0"},"updated_at":"2026-08-30T09:56:50.739Z","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."}