{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.671","julian_year":2026.671,"time":"2026-09-03T04:55:09.541Z","years_from_j2000":26.671,"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-3550","name":"NGC 3550","class":"spiral_galaxy_sb","category":"galaxy","object_type":"Spiral galaxy Sb","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":null,"distance_method":null,"ra_deg":167.66125,"dec_deg":28.76833333333333,"epoch_ra_deg":168.02375,"epoch_dec_deg":28.622685,"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":"Ursa Major","discovered":"1785","featured":false,"url":"https://spacecatalog.org/object/ngc-3550","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"hubble_type":"Sb","wikidata_id":"Q1105329","discovered_by":"William Herschel","ngc_type_code":"GPair","major_axis_arcmin":1.2,"minor_axis_arcmin":1.16792,"morphology_source":"SIMBAD (quality D)","wikipedia_article":"NGC 3550","position_angle_deg":39},"designations":[{"catalog":"LEDA","designation":"LEDA 33927"},{"catalog":"MCG","designation":"MCG +05-27-002"},{"catalog":"NGC","designation":"NGC 3550"},{"catalog":"NGC","designation":"NGC 3550S"},{"catalog":"PGC","designation":"PGC 33927"},{"catalog":"UGC","designation":"UGC 6214"}],"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."}