Impact of the emission profile on the observed ring thickness and baseline domains. We show two extreme cases: (Left) A broad emission profile, leading to large rings and an early transition between n = 1 to n = 2 regimes in the visibility amplitude profile with b₂(145° ) ≈ 200 Gλ. (Right) A highly peaked emission profile, leading to thin rings (the n = 2 subring is not even visible in the image) and a late transition between the n = 1 and n = 2 regimes with b₂(145° ) ≳ 1800 Gλ.