Members of the Boston Conservatory join Concert Choir. The MIT Concert Choir performed Haydn’s “Theresienmesse” Mass in B flat major and Benjamin Britten’s “Festival Te Deum” on Saturday, Dec. 8 in Kresge Auditorium. The Theresienmesse, named after the Empress Maria Theresa of the Two Sicilies, is thought to have been first performed on Sept. 8, 1799. Britten’s “Festival Te Deum” is somewhat more recent, having been composed in 1944 for the centenary of St. Mark’s Church in Swindon, England.