Handbook Reference Guide

What other Imaging Capabilities does HST Offer?

In addition to the FOC, HST offers the WFPC2 camera for wide field imaging. The two cameras compliment each other. In comparison to the FOC, the WFPC2 can offer the following advantages:

Area Coverage: The WF CCDs have an imaging plate scale of ~0.1" per pixel over each of the three 800800 chips, while the PC offers a plate scale of ~0.045" per pixel. This results in a combined field of view of nearly 160160", compared with the 14"14" (maximum) for the FOC. Due to the large size of some objects, it may be necessary to forgo the increased resolution of the FOC in order to image the entire object with the WFPC2.
Red Sensitivity: The WFPC2 CCDs have a peak sensitivity in the red portion of the spectrum with filters all the way out to 1m. In contrast, the FOC cuts off at about 6000Å resulting in the WFPC2 having better sensitivity than the FOC for l > 4000Å.
High Precision Photometry: Photometry with the FOC suffers from variations in the background and other effects which limit the errors to about 5-10%. However, the WFPC2 CCDs provide a better understood background that can result in photometry with lower errors.

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