{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.668","julian_year":2026.668,"time":"2026-09-01T21:56:57.502Z","years_from_j2000":26.668,"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":"m100","name":"M100","class":"intermediate_spiral_galaxy_sabb","category":"galaxy","object_type":"Intermediate spiral galaxy SABb","mag":9.47,"mag_band":"V","abs_mag":null,"abs_mag_band":null,"distance_ly":88957327.83933511,"distance_method":"redshift (CMB frame), flat ΛCDM with H0 = 70 km/s/Mpc","ra_deg":185.72845833333335,"dec_deg":15.821805555555555,"epoch_ra_deg":186.068769,"epoch_dec_deg":15.672894,"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":"Coma Berenices","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/m100","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":10.01,"h_mag":6.82,"j_mag":7.46,"k_mag":6.59,"v_mag":9.47,"redshift":0.005251,"hubble_type":"SABb","redshift_cmb":0.006337844253272218,"ngc_type_code":"G","uncertainties":{"distance_ly":[14495593.687747732,14495593.687747732]},"major_axis_arcmin":6.1,"minor_axis_arcmin":5.62,"position_angle_deg":108,"surface_brightness":22.61,"radial_velocity_km_s":1570},"designations":[{"catalog":"2MASX","designation":"2MASX J12225489+1549205"},{"catalog":"IRAS","designation":"IRAS 12204+1605"},{"catalog":"MCG","designation":"MCG +03-32-015"},{"catalog":"Messier","designation":"M 100"},{"catalog":"NGC","designation":"NGC 4321"},{"catalog":"PGC","designation":"PGC 40153"},{"catalog":"SDSS","designation":"SDSS J122254.91+154920.2"},{"catalog":"UGC","designation":"UGC 7450"}],"source":{"id":"openngc","name":"OpenNGC","url":"https://github.com/mattiaverga/OpenNGC","license":"CC-BY-SA-4.0"},"updated_at":"2026-08-30T09:56:50.739Z","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."}