Is the time of true dawn the same as that specified in calendars, or is it fifty minutes later due to the non-appearance of the white thread?

The true dawn (Al-Fajr Al-Sadiq) is the light that extends across the horizon, followed by no darkness. Its time varies from place to place. Religious rulings are linked to the ascertainment of this time's entry, as Allah Almighty says: (And eat and drink until the white thread of dawn becomes distinct to you from the black thread [of night]). If the calendars align with reality, they should be followed; otherwise, the determinant factor is direct observation. Whoever can see the dawn with their own eyes or through the testimony of a trustworthy person is obliged to act upon that. Otherwise, one should rely on the call to prayer (Adhan) and calendars, striving to ascertain the correct time to the best of their ability.