GPS site testing at chajnantor in Chile

Abstract We present first results on the site coordinates and the atmospheric propagation delay parameters from the permanent Global Positioning System site established at Chajnantor, in the Chilean Andes, at 5000 m altitude. The site is designed to ensure a long-term monument stability. The primary reason behind the site establishment is the future construction of the Atacama Large Millimeter Array (ALMA), a radio astronomy facility, at the same location. There is an interest to observe the site coordinate stability as well as the total radio propagation path delay variations which is possible employing the GPS technique. The fact that the site is known to have mainly a dry delay component makes it also a unique site for GPS accuracy studies. We present first results on the estimated site coordinates and the zenith total and wet atmospheric delays. Structure function results of the delays are included as well as the impact of using different elevation cut off angles in the data processing. We also discuss the performance of the mapping functions used for the estimation of the zenith delay terms.