Assume that apparent visual magnitude $\sim 28$ is the limit at which such systems can reliably determine light variability and spectrum in order to use the Cepheid variable method (the spectrum is necessary to ensure that the star has been identified correctly as a Cepheid variable). Estimate the maximum distance that space-based or ground-based adaptive effects systems can determine by using Cepheids. Assume the limit for standard ground-based telescopes to be apparent visual magnitude $\sim 23$. What is the maximum distance in that case?