{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.809","julian_year":2026.809,"time":"2026-10-23T09:25:20.919Z","years_from_j2000":26.809,"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-6884","name":"HD 6884","class":"b9ia0ek_blue_white_supergiant","category":"star","object_type":"B9Ia0ek blue-white supergiant","mag":10.27,"mag_band":"V","abs_mag":null,"abs_mag_band":null,"distance_ly":null,"distance_method":null,"ra_deg":16.825905,"dec_deg":-72.467683,"epoch_ra_deg":17.040332,"epoch_dec_deg":-72.323426,"epoch_moved_arcsec":0.042,"pm_ra_mas_yr":0.77,"pm_dec_mas_yr":-1.36,"position_epoch_jyear":null,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Tucana","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/hd-6884","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":{"spectral_type":"B9Ia0ek","color_index_bv":0.099,"variable_mag_max":10.144,"variable_mag_min":10.364,"radial_velocity_km_s":170,"spectral_type_source":"SIMBAD (1977A&AS...30..261A, quality C)","proper_motion_ra_mas_yr":0.77,"proper_motion_dec_mas_yr":-1.36},"designations":[{"catalog":"HD","designation":"HD 6884"},{"catalog":"HIP","designation":"HIP 5267"}],"updated_at":"2026-10-01T09:42:28.932Z","citation":{"plain":"SpaceCatalog. HD 6884 [catalogue entry]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/hd-6884","bibtex":"@misc{spacecatalog_hd-6884,\n  author       = {{SpaceCatalog}},\n  title        = {{HD 6884}},\n  howpublished = {SpaceCatalog, data release DR1 (2026-08-21)},\n  year         = {2026},\n  url          = {https://spacecatalog.org/object/hd-6884},\n  note         = {Catalogue entry, data release DR1 (2026-08-21). Values from HYG Database v4.1.}\n}","url":"https://spacecatalog.org/object/hd-6884","release":"DR1","doi":null},"references":[{"bibcode":"1977A&AS...30..261A","ads_url":"https://ui.adsabs.harvard.edu/abs/1977A%26AS...30..261A/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."}