{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.818","julian_year":2026.818,"time":"2026-10-26T19:34:45.223Z","years_from_j2000":26.818,"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":"ngc-6391","name":"NGC 6391","class":"elliptical_galaxy_e","category":"galaxy","object_type":"Elliptical galaxy E","mag":14.85,"mag_band":"B","abs_mag":null,"abs_mag_band":null,"distance_ly":382819227.50529426,"distance_method":"redshift (CMB frame), flat ΛCDM with H0 = 70 km/s/Mpc","ra_deg":262.204125,"dec_deg":58.85088888888889,"epoch_ra_deg":262.304131,"epoch_dec_deg":58.8285,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"position_epoch_jyear":null,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Draco","discovered":"1886","featured":false,"url":"https://spacecatalog.org/object/ngc-6391","source":{"id":"openngc","name":"OpenNGC","url":"https://github.com/mattiaverga/OpenNGC","license":"CC-BY-SA-4.0","attribution":"OpenNGC, Mattia Verga (github.com/mattiaverga/OpenNGC). 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":{"b_mag":14.85,"h_mag":11.01,"j_mag":11.7,"k_mag":10.74,"redshift":0.02704,"hubble_type":"E","wikidata_id":"Q924247","redshift_cmb":0.026860557551170894,"discovered_by":"Lewis A. Swift","ngc_type_code":"G","uncertainties":{"distance_ly":[21005859.76495412,21005859.76495412]},"major_axis_arcmin":0.75,"minor_axis_arcmin":0.52,"position_angle_deg":87,"surface_brightness":23.18,"radial_velocity_km_s":7997},"designations":[{"catalog":"2MASX","designation":"2MASX J17284891+5851032"},{"catalog":"LEDA","designation":"LEDA 60358"},{"catalog":"MCG","designation":"MCG +10-25-049"},{"catalog":"NGC","designation":"NGC 6391"},{"catalog":"PGC","designation":"PGC 60358"},{"catalog":"SDSS","designation":"SDSS J172848.98+585103.1"},{"catalog":"SDSS","designation":"SDSS J172848.98+585103.2"},{"catalog":"SDSS","designation":"SDSS J172848.98+585103.4"},{"catalog":"SDSS","designation":"SDSS J172848.99+585103.2"},{"catalog":"SDSS","designation":"SDSS J172848.99+585103.3"}],"updated_at":"2026-10-01T09:42:28.932Z","citation":{"plain":"SpaceCatalog. NGC 6391 [catalogue entry]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/ngc-6391","bibtex":"@misc{spacecatalog_ngc-6391,\n  author       = {{SpaceCatalog}},\n  title        = {{NGC 6391}},\n  howpublished = {SpaceCatalog, data release DR1 (2026-08-21)},\n  year         = {2026},\n  url          = {https://spacecatalog.org/object/ngc-6391},\n  note         = {Catalogue entry, data release DR1 (2026-08-21). Values from OpenNGC.}\n}","url":"https://spacecatalog.org/object/ngc-6391","release":"DR1","doi":null},"references":[],"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."}