The orchestra is playing fortissimo, and someone in the third row is whispering. Hearing that whisper is the challenge astronomers face at the star HR 8799: four bright giant planets drown out the faint light of a possible fifth, hidden very close to the star.

To catch the whisper, the James Webb Space Telescope used aperture masking: a mask with seven holes turns the mirror into something like a diffraction grating, and the planets' light combines into a pattern that reveals their positions. But that pattern was spoiled by detector noise, for instance the brighter-fatter effect, in which a bright pixel bleeds into its neighbors and smears them. The new Amigo pipeline built a complete model of how light travels from photons to pixels, accounted for this effect and subtracted the interference.

In the residual likelihood map, a peak emerged at 150 milliarcseconds north of the star. That is like spotting a coin from 200 kilometers away. The source's contrast was 2.2×10⁻⁴ in the F380M filter, only slightly above the 3σ threshold, but an orbital fit gives the candidate, f, a semimajor axis of about 7 astronomical units and a mass of 1.7 Jupiter masses. Its position matches one of the stable resonant configurations predicted earlier.

Until now, the inner region of HR 8799 remained out of reach because of systematic detector errors that corrupted interference patterns at small angular separations. Now the method of fully forward-modeling the NIRISS detector opens up regions that were previously hidden. It can be applied right away to archival JWST data to search for faint companions around other stars.

The orchestra plays on, but now we have a score that includes the whisper. All that is left is to wait for follow-up observations to confirm that the fifth planet really moves with the star, rather than being a chance glint.