Nicholas McGegan, the Philharmonia Baroque Orchestra and Chorale are on a big tour this summer, including performances of Handel's Acis and Galatea with the Mark Morris Dance Group at Lincoln Center's Mostly Mozart Festival (Aug. 7-9 and 17), Handel's Teseo at the Tanglewood Festival (Aug.
Slavyanka Chorus of San Francisco is the presenter, the Rachmaninov Festival Chorus of America is the founder of the International Russian Choral Music Festival, the third edition of which is taking place in San Francisco and Berkeley, Aug. 3-10.