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As part of the conceptual and preliminary design processes of the Thirty Meter Telescope (TMT), the TMT site testing team has spent the last five years measuring the atmospheric properties of five candidate mountains in North and South America with an unprecedented array of instrumentation. The site testing period was preceded by several years of analyses(More)
Differential image motion monitors (DIMMs) have become the industry standard for astronomical site characterization. The calibration of DIMMs is generally considered to be routine, but we show that particular care must be paid to this issue if high-accuracy measurements are to be achieved. In a side by side comparison of several DIMMs, we demonstrate that(More)
The multiaperture scintillation sensor (MASS) has become a device widely employed to measure the altitude distribution of atmospheric turbulence. An empirical study is reported that investigates the dependence of the MASS results on the knowledge of the instrumental parameters. Also, the results of a side-by-side comparison of two MASS instruments are(More)
The results on the vertical distribution of optical turbulence above the five mountains which were investigated by the site testing for the Thirty Meter Telescope (TMT) are reported. On San Pedro Mártir in Mexico, the 13 North site on Mauna Kea and three mountains in northern Chile Cerro Tolar, Cerro Armazones and Cerro Tolonchar, MASS-DIMM turbulence(More)
One of the main tools used in the TMT site testing campaign is the turbulence profiler MASS. We describe empirical investigations and a side by side comparison of two MASS systems which were performed in order to identify the accuracy of MASS turbulence data and its dependence on the instrument calibration. The accuracy of the total seeing delivered by the(More)
The optical turbulence conditions as measured between 2004 until end of 2008 above Cerro Tololo, their seasonal as well as nocturnal behavior are presented. A comparison with the MASS-DIMM system of the Thirty Meter Telescope site testing was conducted and identifies an artificially increased seeing component in the data collected by the CTIO DIMM system(More)
The Multi Aperture Scintillation Sensor (MASS) has become a widely employed device to measure the altitude distribution of atmospheric turbulence. An empirical study is reported which investigates the dependence of the MASS results on the knowledge of the instrumental parameters. Also the results of a side by side comparison of two MASS instruments are(More)
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