# Can all astronomical signals be considered Gaussian noise?

While studying the techniques astronomers use to mitigate radio frequency interference (RFI) I found it's often assumed that astronomical signals are (band-limited) Gaussian noise. Is this a reasonable assumption for every type of astronomical observation? Even when searching EM emission from specific elements (e.g. hydrogen line)?

• Not necessarily. Photon counting in CCDs often assumes Poisson noise/statistics. – zephyr Sep 6 '16 at 17:40