<s>[INST] I am a Muslim living in a predominantly non-Muslim country, and I was pondering about when Jumu'ah prayers begin.
Unfortunately, I usually find out about prayer times from the Masjid who communicate it through WhatsApp groups or local religious websites. However I wanted to more about the scholarly legal validity of determining prayer times, specially for Jumu'ah prayers. 
I
As I dug deeper I found out about astronomical prayers which seem to be the method the Western imams use for GüFile for major events like beginning of Ramadan and Eid. 
I have also found that some peoples astronomical calculations vary because they have different methods such as no interpolation vs partly interpolation vs entirely interpolation which affects timing of prayer times.
Lastly at present I have found no regulation on Islamic Prayer Clocks that numerous mosques construct in order to set prayer times, and some of these clocks are not updates and times are incorrect.
How can we standardize prayer time calculations across the globe to avoid his?[/INST]