{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.843","julian_year":2026.843,"time":"2026-11-04T22:14:40.558Z","years_from_j2000":26.843,"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-138629","name":"53 ν² Boo","class":"a2v_white_main_sequence_star","category":"star","object_type":"A2V white main-sequence star","mag":4.98,"mag_band":"V","abs_mag":-0.399,"abs_mag_band":"V","distance_ly":388.28133991871783,"distance_method":"parallax","ra_deg":232.94575922115948,"dec_deg":40.899332,"epoch_ra_deg":233.18881,"epoch_dec_deg":40.80718,"epoch_moved_arcsec":0.544,"pm_ra_mas_yr":-13.73,"pm_dec_mas_yr":-14.92,"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/hd-138629","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":"15318+4054","companions":[{"measured":2015,"magnitude":5.8,"components":"AB","discoverer_code":"A  1634","separation_arcsec":0.2,"position_angle_deg":209},{"measured":2020,"magnitude":13.94,"components":"AB,C","discoverer_code":"BU 1450","separation_arcsec":93.8,"position_angle_deg":89},{"measured":2020,"magnitude":14.19,"components":"AB,D","discoverer_code":"KZA  97","separation_arcsec":117.8,"position_angle_deg":319}],"spectral_type":"A2V","uncertainties":{"distance_ly":[32.60378185100121,39.184361674139105]},"color_index_bv":0.086,"luminosity_solar":125.77664324512543,"radial_velocity_km_s":-17,"spectral_type_source":"SIMBAD (1995ApJS...99..135A, quality C)","surface_temperature_k":8472,"proper_motion_ra_mas_yr":-13.73,"proper_motion_dec_mas_yr":-14.92,"stellar_parameters_method":"Spectroscopic determinations compiled from the literature (PASTEL, Soubiran+ 2016)"},"designations":[{"catalog":"Bayer/Flamsteed","designation":"53 Nu2 Boo"},{"catalog":"HD","designation":"HD 138629"},{"catalog":"HIP","designation":"HIP 76041"},{"catalog":"HR","designation":"HR 5774"}],"updated_at":"2026-11-04T19:31:31.075Z","citation":{"plain":"SpaceCatalog. 53 ν² Boo [catalogue entry]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/hd-138629","bibtex":"@misc{spacecatalog_hd-138629,\n  author       = {{SpaceCatalog}},\n  title        = {{53 ν² Boo}},\n  howpublished = {SpaceCatalog, data release DR1 (2026-08-21)},\n  year         = {2026},\n  url          = {https://spacecatalog.org/object/hd-138629},\n  note         = {Catalogue entry, data release DR1 (2026-08-21). Values from HYG Database v4.1.}\n}","url":"https://spacecatalog.org/object/hd-138629","release":"DR1","doi":null},"references":[{"bibcode":"1995ApJS...99..135A","ads_url":"https://ui.adsabs.harvard.edu/abs/1995ApJS...99..135A/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."}