"it’s the Specter"

Sunset in the Berkshire Hills, a painting by Frederic Edwin Church (1857)
Public DomainSunset in the Berkshire Hills, a painting by Frederic Edwin Church (1857) - Credit: Frederic Edwin Church
This is one of many references to The Berkshire Hills, a book published by the Federal Writers Project during the Great Depression as a guide to western Massachusetts. The book was consulted by Pynchon, and much of the information for this section of the book was taken from this guide. He also consulted it closely when writing 'The Secret Integration', a short story later published in his collection Slow Learner.

The character of Crazy Sue Dunham on page 229 is real, and lifted straight from the pages of The Berkshire Hills. She is also described in 'The Secret Integration'.

As for the Specter, it is described on page 42 of The Berkshire Hills:

'Of the stories and legends about Old Greylock, the one about the 'Specter' is most popular ... The phenomenon of a gigantic shadow of an object reflected in a cloud is so well known as to have a German name, Brockengespenst (Specter of the Brocken) from Brocken, the highest peak of the Hartz Mountains. As Greylockgespenst would be a bit unwieldy for Berkshire, here it is simply called the Specter.'