Which instrument was primarily used for the Hubble Deep Field observations?

The Hubble Deep Field observations primarily used the Wide Field and Planetary Camera 2 (WFPC2). This camera produced the original Hubble Deep Field image in 1995, revealing thousands of distant galaxies in a tiny, seemingly empty region of the sky.

WFPC2 was installed during Hubble’s first servicing mission in 1993. It included corrective optics that fixed the telescope’s famously flawed primary mirror, allowing Hubble to deliver sharp images. Its four CCD detectors combined wide-area imaging with a smaller, higher-resolution planetary-camera view.

Astronomers pointed Hubble at the northern sky for roughly 10 consecutive days, collecting many long exposures through different filters. Combining those exposures made extremely faint galaxies visible, some seen as they were billions of years ago. The same instrument later contributed to the Hubble Deep Field South in 1998.

A common mix-up is Wide Field Camera 3, which replaced WFPC2 in 2009 and has supported later deep-field projects. The Advanced Camera for Surveys also performed important Hubble surveys, but neither was the primary camera for the original 1995 Hubble Deep Field.