–part 3 of the essay An astronomer in Texas–

The first time we could see the observatory. The road divides the image and provides a nice visual cue as to the difference of the telescopes: the left one, called HET, is an experimental, modern 10 meter class telescope that however can only rotate and not tilt. The two telescopes on the right are much older with ages of 50 and 80 years, respectively, but thanks to modernizations they are still actively being used for science. The Harlan J Smith telecope, second from the right, was used to measure the distance to the moon by recording emitted laser beams that were reflected by mirror plates set up by the Apollo mission.