{"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":"2026-09-01T22:56:30.551Z","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-73665","name":"39 Cnc","class":"g8_iii_iiib_yellow_star","category":"star","object_type":"G8+III-IIIb yellow star","mag":6.39,"mag_band":"V","abs_mag":0.036,"abs_mag_band":"V","distance_ly":608.5008215275521,"distance_method":"parallax","ra_deg":130.02675,"dec_deg":20.007788,"epoch_ra_deg":130.412461,"epoch_dec_deg":19.912952,"epoch_moved_arcsec":0.985,"pm_ra_mas_yr":-35.02,"pm_dec_mas_yr":-11.77,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Cancer","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/hd-73665","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"wds_id":"08401+2000","age_years":317589940,"companions":[{"measured":2015,"magnitude":9.03,"components":"AC","discoverer_code":"ENG  37","separation_arcsec":134,"position_angle_deg":309},{"measured":2015,"magnitude":8.79,"components":"AD","discoverer_code":"ENG  37","separation_arcsec":134.9,"position_angle_deg":111},{"measured":2015,"magnitude":6.58,"components":"AB","discoverer_code":"ENG  37","separation_arcsec":151.8,"position_angle_deg":150},{"measured":2002,"magnitude":10.14,"components":"AS","discoverer_code":"SLE 335","separation_arcsec":261.7,"position_angle_deg":325},{"measured":2001,"magnitude":11.63,"components":"AR","discoverer_code":"SLE 685","separation_arcsec":290.3,"position_angle_deg":150}],"mass_solar":3.201,"radius_solar":12.988,"spectral_type":"G8+III-IIIb","uncertainties":{"metallicity_fe_h":[0.015,0.015]},"color_index_bv":0.98,"luminosity_solar":84.25583753398264,"metallicity_fe_h":0.195,"radial_velocity_km_s":35,"spectral_type_source":"SIMBAD (1989ApJS...71..245K, quality B)","surface_gravity_log_g":2.648,"surface_temperature_k":4998,"metallicity_fe_h_source":"Median of 2 spectroscopic determinations in 6 papers, compiled from the literature (PASTEL, Soubiran+ 2016); the error bar is the scatter between them","proper_motion_ra_mas_yr":-35.02,"proper_motion_dec_mas_yr":-11.77,"stellar_parameters_method":"Gaia DR3 model fit (GSP-Phot, FLAME; RUWE ≤ 1.4)","bolometric_luminosity_solar":95.928},"designations":[{"catalog":"Bayer/Flamsteed","designation":"39 Cnc"},{"catalog":"HD","designation":"HD 73665"},{"catalog":"HIP","designation":"HIP 42516"},{"catalog":"HR","designation":"HR 3427"}],"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."}