He worked there for more than 20 years, collecting precise observations of the positions and motions of the planets and stars, achieving an accuracy within a fraction of a minute of an arc, an accuracy unsurpassed until the invention of the telescope.
(He; worked; L:there; T:for more than 20 years) Context(He worked,List([0, 9))):(He; worked collecting; precise observations of the positions and motions of the planets and stars) Context(He worked,List([0, 9))):(He; worked achieving; an accuracy; T:within a fraction of a minute of an arc)
He worked,List([0, 9)) He worked,List([0, 9))
He He He
worked worked collecting worked achieving
L:there T:for more than 20 years
precise observations of the positions and motions of the planets and stars
an accuracy T:within a fraction of a minute of an arc