To help monitor the deformation of nearby Kilauea and Mauna Loa volcanoes, this GPS antenna was installed over a benchmark at the summit of Mauna Kea volcano, Hawai`i. The dish-like antenna collects information transmitted by GPS satellites and passes them to the receiver (hidden from view). The simultaneous measurement of several benchmarks using GPS receivers improves the accuracy of the benchmark positions relative to each other, a key strategy for volcano monitoring. The buildings in the background are astronomical observatories.