{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.654","julian_year":2026.654,"time":"2026-08-27T17:42:09.598Z","years_from_j2000":26.654,"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":"m108","name":"M108","class":"spiral_galaxy_sc","category":"galaxy","object_type":"Spiral galaxy Sc","mag":10.05,"mag_band":"V","abs_mag":null,"abs_mag_band":null,"distance_ly":40551349.23854577,"distance_method":"redshift (CMB frame), flat ΛCDM with H0 = 70 km/s/Mpc","ra_deg":167.87904166666667,"dec_deg":55.67411111111111,"epoch_ra_deg":168.271389,"epoch_dec_deg":55.52837,"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":"1781","featured":false,"url":"https://spacecatalog.org/object/m108","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":10.7,"h_mag":7.37,"j_mag":8.02,"k_mag":7.04,"v_mag":10.05,"redshift":0.002328,"hubble_type":"Sc","wikidata_id":"Q4751","redshift_cmb":0.002896665445160762,"also_known_as":["Surfboard Galaxy"],"discovered_by":"Pierre Méchain","ngc_type_code":"G","uncertainties":{"distance_ly":[14103943.078622632,14103943.078622632]},"major_axis_arcmin":3.98,"minor_axis_arcmin":1.66,"wikipedia_article":"Messier 108","position_angle_deg":79,"surface_brightness":21.7,"radial_velocity_km_s":697},"designations":[{"catalog":"2MASX","designation":"2MASX J11113096+5540268"},{"catalog":"IRAS","designation":"IRAS 11085+5556"},{"catalog":"IRAS","designation":"IRAS F11085+5556"},{"catalog":"LEDA","designation":"LEDA 34030"},{"catalog":"MCG","designation":"MCG +09-18-098"},{"catalog":"Messier","designation":"M 108"},{"catalog":"NGC","designation":"NGC 3556"},{"catalog":"PGC","designation":"PGC 34030"},{"catalog":"SDSS","designation":"SDSS J111131.06+554027.4"},{"catalog":"UGC","designation":"UGC 6225"}],"source":{"id":"openngc","name":"OpenNGC","url":"https://github.com/mattiaverga/OpenNGC","license":"CC-BY-SA-4.0"},"updated_at":"2026-08-27T16:03:54.983Z","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."}