Determining prayer times from prayer calendars

Question

In every city, the local railway time and postal time differ from the local prayer time by more than half an hour. Therefore, please explain the ruling of the Shari'a so that local people may know the prayer time correctly. Some people have insisted on radio time, [but] it has been observed that thunder and lightning cause a difference of two or three seconds and even more, even though [the places] lie within a single mile.

Answer

Prayer times are determined, in principle, by celestial signs, as is known from the Noble Qur'an, the noble hadith and the books of fiqh; prayer calendars are compiled from these same signs. If one is not acquainted with these signs, or the signs do not appear because of clouds, rain and the like, then one is compelled to rely on calendars compiled by experts in the field.

Source: Fatawa Mahmudiyya

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