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Main Authors: Frans, Lott, Backes, Michael, Falcke, Heino, Venturi, Tiziana
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2505.05346
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author Frans, Lott
Backes, Michael
Falcke, Heino
Venturi, Tiziana
author_facet Frans, Lott
Backes, Michael
Falcke, Heino
Venturi, Tiziana
contents The High Energy Stereoscopic System (H.E.S.S.) site and the Gamsberg Mountain have been identified as potential sites for the Africa Millimetre Telescope (AMT). The AMT is poised to observe at millimetre and possibly at submillimetre wavelengths. At these wavelengths, precipitable water vapour (PWV) in the atmosphere is the main source of opacity during observations and therefore needs to be accurately assessed at the potential sites for the AMT. In order to investigate the PWV conditions for the AMT, identical Global Navigation Satellite System (GNSS) stations were installed and used to assess the PWV at the two potential sites. In this study, the accuracy of those PWV measurements by the GNSS stations was assessed by comparing the H.E.S.S. installed GNSS station PWV measurements to that from a 210 GHz Water Vapour Radiometer (WVR) also installed at the H.E.S.S. site. A correlation of 98% and an offset of 0.34 mm was found between the GNSS station and the 210 GHz WVR PWV data when on-site pressure and the Nevada Geodetic Laboratory (NGL) weighted mean temperature ($\mathrm{T_m}$) were used calculate the GNSS station PWV data. In comparison, the offset reduces to 0.15 mm when on-site derived $\mathrm{T_m}$ and pressure were used to calculate the GNSS station PWV. The results show that the GNSS station with on-site meteorological data can be used with high accuracy to reliably determine the PWV conditions at the H.E.S.S. site.
format Preprint
id arxiv_https___arxiv_org_abs_2505_05346
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Analysis of the accuracy of GNSS inferred precipitable water vapour against that from a 210 GHz WVR at the H.E.S.S. site
Frans, Lott
Backes, Michael
Falcke, Heino
Venturi, Tiziana
Instrumentation and Methods for Astrophysics
Atmospheric and Oceanic Physics
Data Analysis, Statistics and Probability
The High Energy Stereoscopic System (H.E.S.S.) site and the Gamsberg Mountain have been identified as potential sites for the Africa Millimetre Telescope (AMT). The AMT is poised to observe at millimetre and possibly at submillimetre wavelengths. At these wavelengths, precipitable water vapour (PWV) in the atmosphere is the main source of opacity during observations and therefore needs to be accurately assessed at the potential sites for the AMT. In order to investigate the PWV conditions for the AMT, identical Global Navigation Satellite System (GNSS) stations were installed and used to assess the PWV at the two potential sites. In this study, the accuracy of those PWV measurements by the GNSS stations was assessed by comparing the H.E.S.S. installed GNSS station PWV measurements to that from a 210 GHz Water Vapour Radiometer (WVR) also installed at the H.E.S.S. site. A correlation of 98% and an offset of 0.34 mm was found between the GNSS station and the 210 GHz WVR PWV data when on-site pressure and the Nevada Geodetic Laboratory (NGL) weighted mean temperature ($\mathrm{T_m}$) were used calculate the GNSS station PWV data. In comparison, the offset reduces to 0.15 mm when on-site derived $\mathrm{T_m}$ and pressure were used to calculate the GNSS station PWV. The results show that the GNSS station with on-site meteorological data can be used with high accuracy to reliably determine the PWV conditions at the H.E.S.S. site.
title Analysis of the accuracy of GNSS inferred precipitable water vapour against that from a 210 GHz WVR at the H.E.S.S. site
topic Instrumentation and Methods for Astrophysics
Atmospheric and Oceanic Physics
Data Analysis, Statistics and Probability
url https://arxiv.org/abs/2505.05346