{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.808","julian_year":2026.808,"time":"2026-10-23T07:09:31.318Z","years_from_j2000":26.808,"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-216435","name":"τ¹ Gru","class":"g0v_yellow_main_sequence_star","category":"star","object_type":"G0V yellow main-sequence star","mag":6.03,"mag_band":"V","abs_mag":3.463,"abs_mag_band":"V","distance_ly":106.3785118433376,"distance_method":"parallax","ra_deg":343.40778,"dec_deg":-48.598286,"epoch_ra_deg":343.806084,"epoch_dec_deg":-48.455492,"epoch_moved_arcsec":6.207,"pm_ra_mas_yr":216.7,"pm_dec_mas_yr":-81.49,"position_epoch_jyear":null,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Grus","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/hd-216435","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":6371824000,"mass_solar":1.15,"radius_solar":1.856,"spectral_type":"G0V","uncertainties":{"metallicity_fe_h":[0.059,0.059]},"color_index_bv":0.621,"luminosity_solar":3.5875668303926154,"metallicity_fe_h":0.24,"radial_velocity_km_s":-1,"spectral_type_source":"SIMBAD (2006AJ....132..161G, quality C)","surface_gravity_log_g":3.923,"surface_temperature_k":5817,"metallicity_fe_h_source":"Median of 15 spectroscopic determinations in 16 papers, compiled from the literature (PASTEL, Soubiran+ 2016); the error bar is the scatter between them","proper_motion_ra_mas_yr":216.7,"proper_motion_dec_mas_yr":-81.49,"stellar_parameters_method":"Gaia DR3 model fit (GSP-Phot, FLAME; RUWE ≤ 1.4)","bolometric_luminosity_solar":3.5547},"designations":[{"catalog":"Bayer/Flamsteed","designation":"Tau1 Gru"},{"catalog":"Gliese","designation":"GJ 9802"},{"catalog":"HD","designation":"HD 216435"},{"catalog":"HIP","designation":"HIP 113044"},{"catalog":"HR","designation":"HR 8700"}],"updated_at":"2026-10-01T09:42:28.932Z","citation":{"plain":"SpaceCatalog. τ¹ Gru [catalogue entry]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/hd-216435","bibtex":"@misc{spacecatalog_hd-216435,\n  author       = {{SpaceCatalog}},\n  title        = {{τ¹ Gru}},\n  howpublished = {SpaceCatalog, data release DR1 (2026-08-21)},\n  year         = {2026},\n  url          = {https://spacecatalog.org/object/hd-216435},\n  note         = {Catalogue entry, data release DR1 (2026-08-21). Values from HYG Database v4.1.}\n}","url":"https://spacecatalog.org/object/hd-216435","release":"DR1","doi":null},"references":[{"bibcode":"2006AJ....132..161G","ads_url":"https://ui.adsabs.harvard.edu/abs/2006AJ....132..161G/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."}