x1 is Sagittarius [astronomical constellation/astrological sign].
From shooter (=celgunta). The Babylonians identified Sagittarius as the god Pabilsaĝ, a strange centaur-like creature firing an arrow from a bow.The sumerian name may be translated as the 'Forefather' or 'Chief Ancestor' (=barda dzena?). In Greek mythology, Sagittarius is identified as a centaur: half human, half horse.