Some rapture watchers and prophecy interpreters have calculated a sequence of days centered around the sign of the abomination of desolation as written about by Daniel the prophet and also written about in the book of Matthew by Jesus.
Joel 2:31-32: 31 The sun will be turned to darkness and the moon to blood before the coming of the great and dreadful day of the Lord. 32 And everyone who calls on the name of the Lord will be saved; for on Mount Zion and in Jerusalem there will be deliverance, as the Lord has said, even among the survivors whom the Lord calls.
THE SIGN OF HIS COMING… REVEALED! Full Presentation by Steve Fletcher
Source: Above Science