{"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":"2026-10-12T03:01:36.619Z","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":"m55","name":"M55","class":"globular_cluster","category":"cluster","object_type":"Globular cluster","mag":6.49,"mag_band":"V","abs_mag":null,"abs_mag_band":null,"distance_ly":17442.843080291437,"distance_method":"Globular-cluster mean distance (Baumgardt & Vasiliev 2021)","ra_deg":294.9975,"dec_deg":-30.962083333333332,"epoch_ra_deg":295.424489,"epoch_dec_deg":-30.900262,"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":"Sagittarius","discovered":"1752","featured":false,"url":"https://spacecatalog.org/object/m55","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":{"v_mag":6.49,"redshift":0.000582,"wikidata_id":"Q13965","discovered_by":"Nicolas Louis de Lacaille","ngc_type_code":"GCl","uncertainties":{"distance_ly":[166.33975263553964,169.60131641270527]},"major_axis_arcmin":12,"wikipedia_article":"Messier 55","distance_reference":"NGC 6809","radial_velocity_km_s":174},"designations":[{"catalog":"HD","designation":"HD 185385"},{"catalog":"IAU cluster","designation":"C 1936-310"},{"catalog":"Messier","designation":"M 55"},{"catalog":"MWSC","designation":"MWSC 3150"},{"catalog":"NGC","designation":"NGC 6809"}],"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."}