UPDATE: On Tuesday, the Vatican will host recently elected Pope Francis I's Installation Mass. Over one hundred and thirty two delegations from around the world will attend the ceremony. There will also be representatives from the Jewish, Muslim, Buddhist, Sikh and Jain communities.
The Papal conclave of 2013 is to be convened as a result of the pending resignation of Pope Benedict XVI. On February 11, Pope Benedict XVI announced he'd step down on February 28 — becoming the first pope to resign in almost six centuries.
Cardinal-Bishop Giovanni Battista Re, from Italy, the most senior cardinal-bishop under 80-years-old, will be presiding the conclave — following a 1996 apostolic constitution by then Pope John Paul II that fixed the start date of the papal conclave at 15 to 20 days after the papacy becomes vacant.
However, because the upcoming vacancy has been known since mid-February, and because of the approaching Holy Week, there has been discussion about beginning the conclave sooner (the Vatican confirmed on February 25 that Benedict XVI issued a motu proprio to provide for a change).
The rule change leaves the College of Cardinals the possibility to bring forward the start of the conclave once all cardinals are present. The Pope also amended the conclave law to allow for the "automatic excommunication" of any non-cardinal who broke the absolute oath of secrecy of the College of Cardinals during the proceedings to select the new pope.