{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.780","julian_year":2026.78,"time":"2026-10-12T19:10:37.013Z","years_from_j2000":26.78,"frame":"date","applied":"Proper motion, then precession and nutation. The catalogued position is carried along the great circle the object's own published motion puts it on, at a constant velocity, from the epoch that position was measured at, 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. The motion runs from position_epoch_jyear where the upstream publishes one — a timed pulsar's position belongs to the year it was timed — and from J2000 where it does not. 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-31551","name":"HD 31551","class":"a2_white_star","category":"star","object_type":"A2 white star","mag":8.57,"mag_band":"V","abs_mag":1.492,"abs_mag_band":"V","distance_ly":849.3656756894785,"distance_method":"parallax","ra_deg":74.58036,"dec_deg":35.135406,"epoch_ra_deg":75.027149,"epoch_dec_deg":35.17669,"epoch_moved_arcsec":0.861,"pm_ra_mas_yr":17.37,"pm_dec_mas_yr":-27.05,"position_epoch_jyear":null,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Auriga","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/hd-31551","source":{"id":"hyg","name":"HYG Database v4.1","url":"https://github.com/astronexus/HYG-Database","license":"CC-BY-SA-4.0","attribution":"HYG Database v4.1, Astronexus (github.com/astronexus/HYG-Database). Fields derived from it stay under CC BY-SA 4.0.","commercial_use":"allowed"},"radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"age_years":379662000,"mass_solar":2.404,"radius_solar":2.336,"spectral_type":"A2","color_index_bv":0.337,"luminosity_solar":22.03941181810109,"radial_velocity_km_s":0,"spectral_type_source":"SIMBAD (1993yCat.3135....0C, quality E)","surface_gravity_log_g":4.032,"surface_temperature_k":9704,"proper_motion_ra_mas_yr":17.37,"proper_motion_dec_mas_yr":-27.05,"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":44.3849},"designations":[{"catalog":"HD","designation":"HD 31551"},{"catalog":"HIP","designation":"HIP 23107"}],"updated_at":"2026-10-01T09:42:28.932Z","attribution":"Data from SpaceCatalog.org. Each record names its upstream in `source`, with that producer's terms in `source.license`, the acknowledgement it asks for in `source.attribution`, and whether its terms allow commercial use in `source.commercial_use`; those terms govern the record, and citing SpaceCatalog does not discharge them."}