Precipitable Water Vapor Measurement using GNSS Data in the Atacama Desert for Millimeter and Submillimeter Astronomical Observations

Precipitable water vapor (PWV) strongly affects the quality of data obtained from millimeter- and submillimeter-wave astronomical observations, such as those for cosmic microwave background (CMB) measurements. Some of these observatories have used radiometers to monitor PWV. In this study, PWV was measured from April 2021 to April 2022 using Global Navigation Satellite System (GNSS) instruments in the Atacama Desert, Chile, where several millimeter and submillimeter-wave telescopes are located. We evaluated the accuracy of these measurements by comparing them to radiometer measurements. We calculated the PWV from GNSS data using Canadian Spatial Reference System Precise Point Positioning (CSRS-PPP), an online software package. When using GNSS data alone, the estimated PWV showed a systematic offset of +1.08 mm. When combining GNSS data with data from a barometer which was co-located with the GNSS receiver, the estimated PWV showed a lower systematic offset of -0.14 mm. The GNSS PWV showed a statistical error of 0.52 mm with an averaging time of an hour. Compared to other PWV measurement methods, GNSS instruments are robust in bad weather conditions, have sufficient time resolution, and are less expensive. By demonstrating good accuracy and precision in low PWV conditions, this paper shows that GNSS instruments are valuable tools for PWV measurements for observing site evaluation and data analysis for ground-based telescopes

The Simons Observatory: Design, integration, and testing of the small aperture telescopes

International audienceThe Simons Observatory (SO) is a cosmic microwave background (CMB) survey experiment that includes small-aperture telescopes (SATs) observing from an altitude of 5,200 m in the Atacama Desert in Chile. The SO SATs will cover six spectral bands between 27 and 280 GHz to search for primordial B-modes to a sensitivity of $\sigma(r)=0.002$, with quantified systematic errors well below this value. Each SAT is a self-contained cryogenic telescope with a 35$^\circ$ field of view, 42 cm diameter optical aperture, 40 K half-wave plate, 1 K refractive optics, and $12,000$ TES detectors. We describe the nominal design of the SATs and present details about the integration and testing for one operating at 93 and 145 GHz

The Simons Observatory: Design, integration, and testing of the small aperture telescopes

International audienceThe Simons Observatory (SO) is a cosmic microwave background (CMB) survey experiment that includes small-aperture telescopes (SATs) observing from an altitude of 5,200 m in the Atacama Desert in Chile. The SO SATs will cover six spectral bands between 27 and 280 GHz to search for primordial B-modes to a sensitivity of $\sigma(r)=0.002$, with quantified systematic errors well below this value. Each SAT is a self-contained cryogenic telescope with a 35$^\circ$ field of view, 42 cm diameter optical aperture, 40 K half-wave plate, 1 K refractive optics, and $12,000$ TES detectors. We describe the nominal design of the SATs and present details about the integration and testing for one operating at 93 and 145 GHz