1. A plenary indulgence is granted to the Christian faithful who, in a church or in an oratory, are present [take part] in a recitation or solemn chant of: ...
1° the hymn Veni Creator ... on the first day of the year, imploring divine assistance for the whole of the coming year...
2° the Te Deum hymn, on the last day of the year, in thanksgiving to God for the favors received in the course of the entire year.
http://throwthebumsoutin2010.blogspot.jp/2017/12/two-plenary-indulgences-this-weekend.html