{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.670","julian_year":2026.67,"time":"2026-09-02T17:51:18.755Z","years_from_j2000":26.67,"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-47129","name":"V640 Mon","class":"o8i_o7_5iii_blue_supergiant","category":"star","object_type":"O8I+O7.5III blue supergiant","mag":6.05,"mag_band":"V","abs_mag":null,"abs_mag_band":null,"distance_ly":null,"distance_method":null,"ra_deg":99.350175,"dec_deg":6.135382,"epoch_ra_deg":99.710038,"epoch_dec_deg":6.11291,"epoch_moved_arcsec":0.052,"pm_ra_mas_yr":-1.84,"pm_dec_mas_yr":0.68,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Monoceros","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/hd-47129","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"wds_id":"06374+0608","companions":[{"measured":2005,"magnitude":11,"components":"AC","discoverer_code":"TRN  22","separation_arcsec":0.8,"position_angle_deg":203},{"measured":2011,"magnitude":11,"components":"AB","discoverer_code":"TRN  22","separation_arcsec":1.2,"position_angle_deg":251}],"radius_solar":13.097,"spectral_type":"O8I+O7.5III","color_index_bv":0.018,"variable_mag_max":6.015,"variable_mag_min":6.075,"radial_velocity_km_s":25,"spectral_type_source":"SIMBAD (2011A&A...525A.101M, quality C)","variable_designation":"V640 Mon","surface_gravity_log_g":3.311,"surface_temperature_k":21546,"proper_motion_ra_mas_yr":-1.84,"proper_motion_dec_mas_yr":0.68,"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"},"designations":[{"catalog":"HD","designation":"HD 47129"},{"catalog":"HIP","designation":"HIP 31646"},{"catalog":"HR","designation":"HR 2422"},{"catalog":"Variable star","designation":"V640 Mon"}],"source":{"id":"hyg","name":"HYG Database v4.1","url":"https://github.com/astronexus/HYG-Database","license":"CC-BY-SA-4.0"},"updated_at":"2026-09-01T22:58:55.274Z","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."}