{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.675","julian_year":2026.675,"time":"2026-09-04T17:25:16.283Z","years_from_j2000":26.675,"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-6644","name":"NGC 6644","class":"planetary_nebula","category":"nebula","object_type":"Planetary nebula","mag":10.7,"mag_band":"V","abs_mag":null,"abs_mag_band":null,"distance_ly":null,"distance_method":null,"ra_deg":278.14470833333337,"dec_deg":-25.129361111111113,"epoch_ra_deg":278.558332,"epoch_dec_deg":-25.109909,"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":"Sagittarius","discovered":"1880","featured":false,"url":"https://spacecatalog.org/object/ngc-6644","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":12.2,"h_mag":11.6,"j_mag":11.56,"k_mag":10.63,"v_mag":10.7,"redshift":0.000647,"wikidata_id":"Q1146858","discovered_by":"Edward Charles Pickering","ngc_type_code":"PN","major_axis_arcmin":0.04,"wikipedia_article":"NGC 6644","radial_velocity_km_s":194},"designations":[{"catalog":"ESO","designation":"ESO 522-033"},{"catalog":"ESO","designation":"ESO 522-33"},{"catalog":"HD","designation":"HD 170839"},{"catalog":"IRAS","designation":"IRAS 18295-2510"},{"catalog":"NGC","designation":"NGC 6644"},{"catalog":"PN","designation":"PN G008.3-07.3"}],"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."}