Explore Further: What Was It Like to
Work in the Prime Focus Cage?
Jesse Greenstein, who spent many years observing with the 200-inch telescope,
reminisced about what it was like to work in the prime focus cage: "When
the telescope was built, an observer had to ride throughout the night in the prime
focus cage to ensure accurate tracking of the telescope. The astronomer ascended
to the cage, eighty feet above the floor, in a specially designed elevator.
"A spectrograph in the cage was used to split starlight into its different
colors, and a photographic plate recorded the intensity of each color. In this
way, each star left its individual 'fingerprint' on the plate. After a careful
set-up, when the instruments are ready and the sun is set, the mirror cover opens
and another night of observing begins.
"You also had to have a tough bladder because, if possible, if it was a good
night, you stayed up from seven o'clock to five. That's ten hours! Working a night
in the small cage high above the primary mirror, feeling closer to the stars than
to the earth, remains an exhilarating and unforgettable experience."