Rosh Hashanah 21: Yes, the Witnesses Matter

What happens if a community misses the notification about Rosh Chodesh? One can keep track to some extent to which months would be "full," and which incomplete. Plus, Levi's trip to Babylonia. Also, the connection to the second day of yom tov, and how this sanctification of the new moon affects Tishrei and Nisan. Also, desecrating Shabbat to get to the court to testify about the new moon. And getting to the court in time for Tishrei and Nisan. And the difference between post-Temple and Temple periods of time. Plus, when the clear weather keeps a witness home. And when many witnesses go, but don't keep the extras home. Plus, clarify the term for "clear." And Moshe as close to God.