The fifteenth-century emergence of Ottoman scientific endeavours occurred at a fortunate time when scientific knowledge in the Islamic world was already advanced. Since the Ottomans had no intention of reinventing the wheel, they began accumulating this already advanced knowledge via copying manuscripts, providing safe haven for scholars fleeing political instability in the East, establishing madrasas, and other methods. Most of the mathematical sciences such as algebra, arithmetic, and ilm alhay'a, were transmitted from the successive schools of Maragha, Tabriz, and Samarciand. The science of timekeeping, however, had a unique source: the Mamluks. During the thirteenth-fifteenth centuries, Mamluk astronomers worked exclusively on timekeeping and produced arguably the best treatises in this discipline. It was, therefore, no surprise that the Ottoman reception of timekeeping was based on these works. This paper will discuss the exact starting point of this transmission and introduce 'Umar al-Dimashqi, a Mamluk astronomer from Damascus who lived in Istanbul and Edirne, as the responsible party. The texts in his timekeeping compendium, the Hamidiye 1453, will be examined in detail and its role as a bridge between Mamluk, Samarciand, and Istanbul knowledge traditions will be discussed.