{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.778","julian_year":2026.778,"time":"2026-10-11T23:42:49.996Z","years_from_j2000":26.778,"frame":"date","applied":"Proper motion, then precession and nutation. The catalogued position is carried along the great circle the object's own published motion puts it on, at a constant velocity, from the epoch that position was measured at, 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. The motion runs from position_epoch_jyear where the upstream publishes one — a timed pulsar's position belongs to the year it was timed — and from J2000 where it does not. 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-1990","name":"NGC 1990","class":"star","category":"star","object_type":"Star","mag":1.69,"mag_band":"V","abs_mag":null,"abs_mag_band":null,"distance_ly":null,"distance_method":null,"ra_deg":84.05341666666666,"dec_deg":-1.2019166666666665,"epoch_ra_deg":84.395425,"epoch_dec_deg":-1.184569,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"position_epoch_jyear":null,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Orion","discovered":"1786","featured":false,"url":"https://spacecatalog.org/object/ngc-1990","source":{"id":"openngc","name":"OpenNGC","url":"https://github.com/mattiaverga/OpenNGC","license":"CC-BY-SA-4.0","attribution":"OpenNGC, Mattia Verga (github.com/mattiaverga/OpenNGC). Fields derived from it stay under CC BY-SA 4.0.","commercial_use":"allowed"},"radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":1.51,"h_mag":2.07,"j_mag":2.07,"k_mag":2.16,"v_mag":1.69,"redshift":0.000003,"wikidata_id":"Q1046370","discovered_by":"William Herschel","ngc_type_code":"*","wikipedia_article":"NGC 1990","radial_velocity_km_s":27,"surface_gravity_log_g":2.85,"surface_temperature_k":25835,"stellar_parameters_method":"Spectroscopic determinations compiled from the literature (PASTEL, Soubiran+ 2016)"},"designations":[{"catalog":"46","designation":"46 Ori"},{"catalog":"BD","designation":"BD -01 0969"},{"catalog":"Common name","designation":"Alnilam"},{"catalog":"Eps","designation":"Eps Ori"},{"catalog":"HD","designation":"HD 37128"},{"catalog":"HIP","designation":"HIP 26311"},{"catalog":"IDS","designation":"IDS 05311-0116 A"},{"catalog":"Lynds","designation":"LBN 205.42-17.78"},{"catalog":"Lynds","designation":"LBN 940"},{"catalog":"NGC","designation":"NGC 1990"},{"catalog":"TYC","designation":"TYC 4766-2450-1"},{"catalog":"WDS","designation":"WDS J05362-0112A"}],"updated_at":"2026-10-01T09:42:28.932Z","attribution":"Data from SpaceCatalog.org. Each record names its upstream in `source`, with that producer's terms in `source.license`, the acknowledgement it asks for in `source.attribution`, and whether its terms allow commercial use in `source.commercial_use`; those terms govern the record, and citing SpaceCatalog does not discharge them."}