What is the maximum resolution of a telescope array, or interferometer?
For a telescope array, or interferometer, the resolution (the finest details it can distinguish) depends on the separation of the individual elements of the array. The resolution improves as the separation of the elements increases, which is why widely spread interferometer arrays are important for high resolution observations. This is different from a single telescope, where the resolution depends instead on the diameter of the individual telescope (see previous FAQ). The angular size θ (measured in radians) of the smallest details that the array can distinguish is given by θ≈λ/B, where λ is the wavelength of the light and B the maximum “baseline”, the separation between a pair of elements in the array. This expression can be compared with the equivalent one for a single telescope of θ≈λ/D, where D is the diameter of the telescope. In other words, the interferometer can be thought of as having the resolution of a single telescope as large as the whole array. For example, the Atacama L
