{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.680","julian_year":2026.68,"time":"2026-09-06T12:30:24.945Z","years_from_j2000":26.68,"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-3557b","name":"NGC 3557B","class":"elliptical_galaxy_e","category":"galaxy","object_type":"Elliptical galaxy E","mag":12.55,"mag_band":"V","abs_mag":null,"abs_mag_band":null,"distance_ly":148989597.03364286,"distance_method":"redshift (CMB frame), flat ΛCDM with H0 = 70 km/s/Mpc","ra_deg":167.383875,"dec_deg":-37.34963888888889,"epoch_ra_deg":167.701684,"epoch_dec_deg":-37.495182,"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":"Centaurus","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/ngc-3557b","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":13.54,"h_mag":9.35,"j_mag":10.05,"k_mag":9.09,"v_mag":12.55,"redshift":0.009507,"hubble_type":"E","wikidata_id":"Q1105348","redshift_cmb":0.010580995004733751,"discovered_by":"John Frederick William Herschel","ngc_type_code":"G","uncertainties":{"distance_ly":[15315720.668743744,15315720.668743744]},"major_axis_arcmin":1.83,"minor_axis_arcmin":0.52,"position_angle_deg":110,"surface_brightness":23.65,"radial_velocity_km_s":2837},"designations":[{"catalog":"2MASX","designation":"2MASX J11093213-3720586"},{"catalog":"ESO","designation":"ESO 377-015"},{"catalog":"ESO","designation":"ESO 377-15"},{"catalog":"ESO-LV","designation":"ESO-LV 377-0150"},{"catalog":"LEDA","designation":"LEDA 33824"},{"catalog":"MCG","designation":"MCG -06-25-004"},{"catalog":"NGC","designation":"NGC 3557B"},{"catalog":"PGC","designation":"PGC 33824"}],"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."}