What is the time for Imsak in Ramadan for the city of Istanbul, Turkey, given that Imsak is an hour and a half before sunrise?

The time for the lawful cessation of eating and drinking (imsak) is the appearance of the true dawn (al-Fajr al-Sadiq), in accordance with Allah Almighty's saying: ﴿And eat and drink until the white thread of dawn becomes distinct to you from the black thread [of night]﴾ [Al-Baqarah: 187]. And as the Prophet, peace and blessings be upon him, clarified: «Dawn is of two types: a dawn when food becomes unlawful and prayer becomes lawful, and a dawn when prayer becomes unlawful and food becomes lawful.» There is no basis for stopping eating ten or fifteen minutes before dawn. So, whoever can observe the dawn should act accordingly. And whoever cannot, should rely on asking experts, or imitating the muezzins of mosques, or the local calendar. The time of imsak is not fixed and changes with the seasons, but the determining factor is the appearance of the true dawn.