Magdalena Ridge Observatory site noise study

We performed a seismic site characterization in central New Mexico for the approx. 350-m baseline Magdalena Ridge Observatory (MRO) astronomical interferometer, which will operate at wavelengths between 600 nm and 2400 nm. The operation of an interferometer requires that optical path lengths be stable to within considerably less than one wavelength over the measurement timescale. The study analyzed 1-hour absolute and differential background noise windows at element locations between February and October of 2003. Data were acquired with IRIS PASSCAL stations consisting of four 3-component broadband 120-s STS-2 sensors in shallow vaults and Quanterra Q330 digitizers with both real-time 802.11 telemetry and on-site Baler14 recorders. Sensors were deployed at the ends of each of the three interferometer arms, and at the center of the array.