{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.846","julian_year":2026.846,"time":"2026-11-05T21:12:18.859Z","years_from_j2000":26.846,"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":"alkalurops-b","name":"Alkalurops B","class":"g0v_yellow_main_sequence_star","category":"star","object_type":"G0V yellow main-sequence star","mag":6.51,"mag_band":"V","abs_mag":3.687,"abs_mag_band":"V","distance_ly":119.69484791086474,"distance_method":"parallax (Gaia DR3, zero point corrected)","ra_deg":231.12861164652415,"dec_deg":37.3473,"epoch_ra_deg":231.38499,"epoch_dec_deg":37.252181,"epoch_moved_arcsec":4.418,"pm_ra_mas_yr":-140.95,"pm_dec_mas_yr":84.97,"position_epoch_jyear":null,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Boötes","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/alkalurops-b","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":"15245+3723","age_years":5641691000,"companions":[{"measured":2023,"magnitude":7.63,"components":"Ba,Bb","discoverer_code":"STF1938","separation_arcsec":2.3,"position_angle_deg":2}],"mass_solar":1.074,"radius_solar":1.228,"spectral_type":"G0V","uncertainties":{"distance_ly":[0.07386094768450589,0.0739522161202136]},"color_index_bv":0.6,"luminosity_solar":2.9194373780088787,"radial_velocity_km_s":-8.6,"spectral_type_source":"SIMBAD (1981ApJS...45..437A, quality C)","surface_gravity_log_g":4.205,"surface_temperature_k":5988,"proper_motion_ra_mas_yr":-140.95,"proper_motion_dec_mas_yr":84.97,"stellar_parameters_method":"Gaia DR3 model fit (GSP-Phot, FLAME; RUWE ≤ 1.4) — low confidence: Gaia's classifier calls the source a binary, which GSP-Phot fitted as one star","bolometric_luminosity_solar":1.7473},"designations":[{"catalog":"Bayer/Flamsteed","designation":"51 Mu2 Boo"},{"catalog":"Common name","designation":"Alkalurops B"},{"catalog":"Gliese","designation":"GJ 3904B"},{"catalog":"HD","designation":"HD 137392"},{"catalog":"HIP","designation":"HIP 75415"},{"catalog":"HR","designation":"HR 5734"}],"updated_at":"2026-11-04T19:31:31.075Z","citation":{"plain":"SpaceCatalog. Alkalurops B [catalogue entry]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/alkalurops-b","bibtex":"@misc{spacecatalog_alkalurops-b,\n  author       = {{SpaceCatalog}},\n  title        = {{Alkalurops B}},\n  howpublished = {SpaceCatalog, data release DR1 (2026-08-21)},\n  year         = {2026},\n  url          = {https://spacecatalog.org/object/alkalurops-b},\n  note         = {Catalogue entry, data release DR1 (2026-08-21). Values from HYG Database v4.1.}\n}","url":"https://spacecatalog.org/object/alkalurops-b","release":"DR1","doi":null},"references":[{"bibcode":"1981ApJS...45..437A","ads_url":"https://ui.adsabs.harvard.edu/abs/1981ApJS...45..437A/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."}