The Diyanet Astronomical Criteria

Diyanet works in close collaboration with the Kandilli Observatory of Boğaziçi University in Istanbul and TÜBİTAK. Calculations compute the exact moment of moonset after sunset, ensuring compliance with classical Islamic legal rulings on crescent visibility.

The 1978 Istanbul International Consensus

Turkey's methodology stems from the historic 1978 conference attended by international Islamic scholars and astronomers, establishing mathematical criteria that eliminate visual ambiguity while respecting sharia principles.

Day Transition Dynamics

The civil calendar updates at 12:00 AM midnight Turkey Time (TRT / Europe/Istanbul, UTC+3), while religious observance begins at sunset with the Maghrib prayer.