To Fast While the 1st of the Month Is not Ascertained

To Fast While the 1st of the Month Is not Ascertained

17. If it is difficult to ascertain the beginning of the month of Ramadan, or Eid ul-Fitr, because of inability to observe the crescent at the beginning of the month due to clouds or for some other reason, and if the count of the month of Sha‘bān or the month of Ramadan did not add up to 30 days, is it permissible for us in Japan to go by the horizon in Iran or should we rely on the regular calendar? What is the rule?
A: If the crescent has not been ascertained even by being sighted in an adjacent city of the same horizon, on the evidence of two just witnesses, or on the basis of a decree by a mujtahīd, it is obligatory to observe caution until the beginning of the month is ascertained.

Source: Hadana adopted from the Istiftaat of the Grand Ayatollah Khamenei