Usually we measure the speed of light using light generated here on Earth or coming from the Sun or other stars, but have we ever tried to measure the speed of the light coming from distant galaxies? As in directing that light into an apparatus and measure its average velocity over a round-trip. And do you know if any experiment that measured the Shapiro time delay also attempted to measure whether the light that came back was also slightly redshifted? Regarding the first question I know that general relativity predicts the result would be c, but I wonder whether any experiment has actually checked that. Regarding the second question I'm guessing general relativity would predict no redshift but I'm not sure?