Extended Data Figure 4: Hα detection noise statistics.

a, Histogram of noise (non-planet) pixel values in the SNR map within the speckle dominated regime (black line) compared to a Normal distribution (red line). The black arrow denotes the location of the peak SNR value for LkCa 15 b. b, Histogram of the peak values in all noise apertures (see Extended Data Fig. 5) within the control radius (black line) compared to a Normal distribution (red line). The black arrow shows the peak pixel value in the LkCa 15 b aperture.