{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.818","julian_year":2026.818,"time":"2026-10-26T18:28:24.127Z","years_from_j2000":26.818,"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-170073","name":"39 Dra","class":"a1v_f5v_white_main_sequence_star","category":"star","object_type":"A1V+F5V white main-sequence star","mag":4.98,"mag_band":"V","abs_mag":1.221,"abs_mag_band":"V","distance_ly":184.16517714689232,"distance_method":"parallax","ra_deg":275.977605,"dec_deg":58.800736,"epoch_ra_deg":276.075624,"epoch_dec_deg":58.814803,"epoch_moved_arcsec":1.947,"pm_ra_mas_yr":-37.64,"pm_dec_mas_yr":62.08,"position_epoch_jyear":null,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Draco","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/hd-170073","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":{"wds_id":"18239+5848","age_years":571484400,"companions":[{"measured":2022,"magnitude":8.07,"components":"AB","discoverer_code":"STF2323","separation_arcsec":3.7,"position_angle_deg":347},{"measured":2003,"magnitude":13.3,"components":"AG","discoverer_code":"STF2323","separation_arcsec":35.8,"position_angle_deg":244},{"measured":2000,"magnitude":14.4,"components":"AH","discoverer_code":"STF2323","separation_arcsec":44.2,"position_angle_deg":93},{"measured":2022,"magnitude":7.95,"components":"AC","discoverer_code":"STF2323","separation_arcsec":89.2,"position_angle_deg":19},{"measured":2008,"magnitude":12.9,"components":"AF","discoverer_code":"STF2323","separation_arcsec":150.5,"position_angle_deg":80}],"mass_solar":2.138,"radius_solar":2.298,"spectral_type":"A1V+F5V","color_index_bv":0.082,"luminosity_solar":28.287853879701313,"radial_velocity_km_s":-15,"spectral_type_source":"SIMBAD (1977AJ.....82..431L, quality C)","surface_gravity_log_g":3.925,"surface_temperature_k":8790,"proper_motion_ra_mas_yr":-37.64,"proper_motion_dec_mas_yr":62.08,"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":28.3868},"designations":[{"catalog":"Bayer/Flamsteed","designation":"39 Dra"},{"catalog":"HD","designation":"HD 170073"},{"catalog":"HIP","designation":"HIP 90156"},{"catalog":"HR","designation":"HR 6923"}],"updated_at":"2026-10-01T09:42:28.932Z","citation":{"plain":"SpaceCatalog. 39 Dra [catalogue entry]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/hd-170073","bibtex":"@misc{spacecatalog_hd-170073,\n  author       = {{SpaceCatalog}},\n  title        = {{39 Dra}},\n  howpublished = {SpaceCatalog, data release DR1 (2026-08-21)},\n  year         = {2026},\n  url          = {https://spacecatalog.org/object/hd-170073},\n  note         = {Catalogue entry, data release DR1 (2026-08-21). Values from HYG Database v4.1.}\n}","url":"https://spacecatalog.org/object/hd-170073","release":"DR1","doi":null},"references":[{"bibcode":"1977AJ.....82..431L","ads_url":"https://ui.adsabs.harvard.edu/abs/1977AJ.....82..431L/abstract","quantity":"properties.spectral_type_source"}],"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."}