{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.663","julian_year":2026.663,"time":"2026-08-31T07:07:21.457Z","years_from_j2000":26.663,"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":"ic-2991","name":"IC 2991","class":"spiral_galaxy_sc","category":"galaxy","object_type":"Spiral galaxy Sc","mag":15.83,"mag_band":"B","abs_mag":null,"abs_mag_band":null,"distance_ly":495348728.95381427,"distance_method":"redshift (CMB frame), flat ΛCDM with H0 = 70 km/s/Mpc","ra_deg":181.30212500000002,"dec_deg":10.64036111111111,"epoch_ra_deg":181.645807,"epoch_dec_deg":10.490897,"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":"Virgo","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/ic-2991","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":15.83,"h_mag":13.67,"j_mag":13.99,"k_mag":13.49,"redshift":0.03338,"hubble_type":"Sc","wikidata_id":"Q3688306","redshift_cmb":0.034561538835934824,"ngc_type_code":"G","uncertainties":{"distance_ly":[24574832.484905463,24574832.484905463]},"major_axis_arcmin":0.67,"minor_axis_arcmin":0.24,"position_angle_deg":35,"surface_brightness":23.19,"radial_velocity_km_s":9840},"designations":[{"catalog":"2MASX","designation":"2MASX J12051250+1038252"},{"catalog":"IC","designation":"IC 2991"},{"catalog":"LEDA","designation":"LEDA 38273"},{"catalog":"MCG","designation":"MCG +02-31-025"},{"catalog":"PGC","designation":"PGC 38273"},{"catalog":"SDSS","designation":"SDSS J120512.50+103825.2"},{"catalog":"SDSS","designation":"SDSS J120512.51+103825.3"}],"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."}