Persian poet, mathematician, and astronomer, noted for the Rubáiyát, a collection of quatrains, popularised in the West by Edward FitzGerald
All answers having "Persian poet, mathematician, and astronomer, noted for the Rubáiyát, a collection of quatrains, popularised in the West by Edward FitzGerald" as clue:
9 Character Answers:
BOFORSGUN
11 Character Answers:
OMARKHAYYAM
Crossword Answers