When you look out your kitchen window, the view outside is framed by the shape of that window. Likewise, Hubble’s view is framed by the instrument making the observation. One of Hubble’s instruments — the Wide Field and Planetary Camera 2, or WFPC2 for short — results in images with a peculiar stair-step shape.

WFPC2 is actually made up of four cameras. Each camera records a separate image that represents one part of the overall view. It’s rather like seeing a view through a four-paned household window. But WFPC2 has a unique feature. One of its cameras records a magnified view of the section it’s observing, which allows us to see finer detail in that section.

During image processing the magnified view is reduced to the proportion of the other three, resulting in one small image and three larger images.

The stair-step shape emerges when the four images are stitched together to make the final image.

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