Possible Clues:

• Poet Amy
• Astronomer Percival
• Robert ..., US poet
• Poet who mourned the Union dead?
• Whistler's Massachusetts birthplace
• Pulitzer-winning poet of 1947 and 1974
• Look thoroughly? That's an astronomer
• Robert --, US poet who won the 1947 Pulitzer Prize for Poetry for 'Lord Weary's Castle'
• Amy - - , American poet 1874-1925
• Massachusetts city on the Merrimack