Tuesday, the 17th day of the Hebrew month of Nissan and the 22nd day in April, is the second day of counting of the Omer towards the end of the 49-day counting the night before the festival of Shavuot (Pentecost). The blessing before the daily counting must be said at night, and if one forgets, he may count without a blessing during the following day.
The period of counting of the Omer includes the period in which Jews remember the deaths of 24,000 students of Rabbi Akiva, and festive events, such as weddings, are prohibited, except on Lag b'Omer, the 33rd day of the counting. There are different customs concerning the mourning period.
Music and dancing are allowed on Independence Day, Jerusalem Reunification Day and after the beginning of the month of Sivan, the week before Shavuot.