After posting the question Are questions on the historical inauguration of some "utilities" or "methods" on topic? on meta I finally decided to ask ask it here:
I'm pretty sure that calendars or methods to calculate the moon phases have been developed in the golden ages of islamic caliphates, as there have been lots of scientists such al-Biruni (even Imam Malik has been said to have written a book about that) and many others. But what I'd like to know is:
When and where scholars or clerics introduced or accepted them as a utility for declaring or calculating important dates like 1st day of Ramadan?
Any details on this historical inauguration would be fine!
I think of information like: how was the general acceptance at the time, who was the cleric, who was the person or scientists whom's caclulation methods or calendar was accepted ...