I was going through the schedules for WGBH and WTVS for August. Looks like WGBH must have a Pledge period during the month. Some of the music programs listed on the schedule are:

WGBH
August 12      9:00pm   Nature "John Denver: Let This Be a Voice"
August 15      10:00pm   All-Star Bluegrass Celebration II
August 16      4:00pm   Dusty Springfield: Reflections
      7:00pm   All-Star Bluegrass Celebration II
August 17      5:00pm   Nature "John Denver: Let This Be a Voice"
      6:30pm   Dusty Springfield: Reflections
      8:00pm   American Soundtrack: This Land Is Your Land
August 20      7:00pm   Great Performances "The Art of Violin"
August 22      10:00pm   Nature "John Denver: Let This Be a Voice"
August 23      4:30pm   Blue Suede Shoes: A Rockabilly Session With Carl Perkins
      6:00pm   American Soundtrack: Rhythm, Love and Soul
      9:00pm   Simon and Garfunkel: The Concert in Central Park
August 24      4:00pm   Broadway's Lost Treasures
August 26      10:00pm   Blue Suede Shoes: A Rockabilly Session With Carl Perkins
August 27      10:42pm   Nature "John Denver: Let This Be a Voice"
August 28      8:30pm   Simon and Garfunkel: The Concert in Central Park
August 29      10:00pm   Broadway's Lost Treasures
August 30      midnight   Austin City Limits "Mary Chapin Carpenter/Nanci Griffith"
 
WTVS
August 8      10:30pm   Chieftains: Down the Old Plank Road
      midnight   Cahal Dunne's Thank You, America
August 10      2:00am   All-Star Bluegrass Celebration
August 17      4:00pm   Cahal Dunne's Thank You, America
      5:00pm   Broadway's Lost Treasures
August 21      11:00pm   American Soundtrack: This Land Is Your Land

The times are Eastern Time Zone.