{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.688","julian_year":2026.688,"time":"2026-09-09T05:08:43.115Z","years_from_j2000":26.688,"frame":"date","applied":"Proper motion, then precession and nutation. The catalogued J2000 position is carried along the great circle the object's own published motion puts it on, at a constant velocity, 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. 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-6884","name":"NGC 6884","class":"planetary_nebula","category":"nebula","object_type":"Planetary nebula","mag":10.9,"mag_band":"V","abs_mag":null,"abs_mag_band":null,"distance_ly":12491.789266551274,"distance_method":"Statistical distance scale for planetary nebulae (Stanghellini+ 2008)","ra_deg":302.59875,"dec_deg":46.46083333333333,"epoch_ra_deg":302.809082,"epoch_dec_deg":46.53971,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Cygnus","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/ngc-6884","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":12.6,"h_mag":11.19,"j_mag":11.16,"k_mag":10.37,"v_mag":10.9,"redshift":-0.000119,"wikidata_id":"Q1277936","ngc_type_code":"PN","major_axis_arcmin":0.1,"wikipedia_article":"NGC 6884","distance_reference":"NGC 6884","radial_velocity_km_s":-36},"designations":[{"catalog":"HD","designation":"HD 191916"},{"catalog":"IRAS","designation":"IRAS 20088+4618"},{"catalog":"NGC","designation":"NGC 6766"},{"catalog":"NGC","designation":"NGC 6884"},{"catalog":"PN","designation":"PN G082.1+07.0"}],"source":{"id":"openngc","name":"OpenNGC","url":"https://github.com/mattiaverga/OpenNGC","license":"CC-BY-SA-4.0"},"updated_at":"2026-09-02T19:50:56.720Z","attribution":"Data from SpaceCatalog.org. Individual records carry their source and license in `source`; attribution is required for CC-BY and CC-BY-SA rows."}