STEREO/SECCHI Imagers: Fields of View

There are five imaging instruments on each STEREO spacecraft. They form STEREO's SECCHI imaging suite.

Together they image all the way from the Sun to the orbit of Earth - the first time this has been done with a single spacecraft. This is such a distance across the sky that it is difficult to depict on a flat screen.

The image above shows the fields of view (FOV) of the three sun centered imagers:

EUVI - Shows the Sun in extreme UV light out to 1.7 times the Sun's radius
Cor1 - Visible light coronagraph which observes from 1.5 to 4 solar radii
Cor2 - visible light coronagraph which observes out to 15 solar radii

In this depiction Earth's orbit is on the left and the Sun is on the right.

In addition to the data from three sun-centered imagers show above, here we also see data from the two Heliocentric Imagers, visible light imagers which are pointed away from the Sun:

HI1 - Observes visible light from the outer part of Cor2's field of view to about a third of the distance to Earth's orbit
HI2 - Completes the Sun-Earth view by extending the view to Earth's orbit

The illustration only shows the fields of view of the Ahead spacecraft. The Behind spacecraft observes the area between the Sun and Earth from the other direction, so that between them we see 180 degrees of sky.