ATST enclosure: seeing performance, thermal modeling, and error budgets

The enclosure for the Advanced Technology Solar Telescope (ATST) is both a wind shield and a source of seeing. Its design must minimize self-induced seeing while remaining within cost constraints and balancing with other error budget items. We report the methods used to quantify seeing performance, including thermal modeling, seeing estimation, and systems engineering error budgets. Thermal modeling is performed using a commercial software package that applies measured site weather data to a CAD-generated enclosure model. Seeing estimation is performed using a simple aerodynamic treatment. The results, along with measured site wind and temperature distributions, are combined into a "bottom-up" performance prediction using Monte Carlo techniques.