Āryabhaṭīya

thumb| Reference of Kuttaka in Aryabhatiya

Aryabhatiya (IAST: ') or Aryabhatiyam ('), a Sanskrit astronomical treatise, is the magnum opus and only known surviving work of the 5th century Indian mathematician Aryabhata. Historian of astronomy Roger Billard estimates that the book was composed around 510 CE based on historical references it mentions.