Diagram of the focal plane :
sismology program on the right / exoplanet prgram on the left.
Paris Observatory / LESIA / UFE
The targets of the sismology program are bright, and their brightness is measured every 30 seconds, with an accuracy of 1 ten thousandth. The pointing direction is chosen to observe at least one very bright sismology target (magnitude close to 6, visible to the naked eye), for which the accuracy will be so good that it will be possible to detect oscillations as weak as those observed in the Sun.
The targets of the exoplanet program are much less luminous, and therefore require a longer exposure time (8 minutes) to reach an accuracy comparable to the precision necessary for the detection of transits.
In the diagram of the focal plane we can see the two detectors dedicated to the sismology program on the left, and on the right the two detectors dedicated to the exoplanet program.