{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.682","julian_year":2026.682,"time":"2026-09-06T22:17:42.727Z","years_from_j2000":26.682,"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-207538","name":"HD 207538","class":"o9_7iv_blue_subgiant","category":"star","object_type":"O9.7IV blue subgiant","mag":7.31,"mag_band":"V","abs_mag":null,"abs_mag_band":null,"distance_ly":null,"distance_method":null,"ra_deg":326.91579,"dec_deg":59.700375,"epoch_ra_deg":327.116984,"epoch_dec_deg":59.824568,"epoch_moved_arcsec":0.098,"pm_ra_mas_yr":-2.68,"pm_dec_mas_yr":-2.51,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Cepheus","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/hd-207538","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"wds_id":"21477+5942","companions":[{"measured":2007,"magnitude":9.3,"components":null,"discoverer_code":"PET  11","separation_arcsec":0.1,"position_angle_deg":194}],"radius_solar":8.322,"spectral_type":"O9.7IV","color_index_bv":0.278,"radial_velocity_km_s":-14.3,"spectral_type_source":"SIMBAD (2011ApJS..193...24S, quality C)","surface_gravity_log_g":3.744,"surface_temperature_k":26370,"proper_motion_ra_mas_yr":-2.68,"proper_motion_dec_mas_yr":-2.51,"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 207538"},{"catalog":"HIP","designation":"HIP 107598"}],"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."}