is he associated with any discoveries?
Yes, he discovered two moons of Saturn, Mimas and Enceladus; as well as two moons of Uranus, Titania and Oberon.
William Herschel
In his later career, Herschel discovered two moons of Saturn, Mimas and Enceladus; as well as two moons of Uranus, Titania and Oberon. 
how many globular clusters are in the milky way About 150 to 158 currently known what are these? It is a spherical collection of stars that orbits a galactic core. do they contain metal? It consists of Population II stars, to which astronomers refer to as heavier elements as metals and to the proportions of these elements as the metallicity. how the last term calculated? Astronomers use several different methods to describe and approximate metal abundances, depending on the available tools and the object of interest. who were among the observers of this collection of stars? Abraham Ihle and William Herschel. who was the second? Astronomer and composer of music. has any telescope been named after him? Yes, Herschelian telescope.
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William Herschel [SEP] Further discoveries
In his later career, Herschel discovered two moons of Saturn, Mimas and Enceladus; as well as two moons of Uranus, Titania and Oberon. He did not give these moons their names; they were named by his son John in 1847 and 1852, respectively, after his death. Herschel measured the axial tilt of Mars and discovered that the martian ice caps, first observed by Giovanni Domenico Cassini (1666) and Christiaan Huygens (1672), changed size with that planet's seasons. It has been suggested that Herschel discovered rings around Uranus. Herschel introduced but did not create the word "asteroid", meaning "star-like" (from the Greek "asteroeides", "aster" "star" + "-eidos" "form, shape"), in 1802 (shortly after Olbers discovered the second minor planet, 2 Pallas, in late March), to describe the star-like appearance of the small moons of the giant planets and of the minor planets; the planets all show discs, by comparison.