Four Years of Optical Turbulence Monitoring at the Cerro Tololo Inter-American Observatory (CTIO)

The optical turbulence conditions as measured between 2004 through the 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 under northerly winds. Evidence is shown that this increased turbulence is caused by the telescope dome. A correction for this effect is attempted and applied to the CTIO-DIMM data. The MASS data of this comparison campaign allow constraints to be set on the general assumption of uniform turbulent layers above a site.