Measurement of dome turbulence intensity from scintillation pattern in the pupil of the telescope

Abstract: We present measurements of optical turbulence (OT) power inside the telescope dome using an instrument registering fluctuations of intensity of a bright star at a plane conjugated to -2 km below the pupil of the telescope - Domecam. The measurements were conducted at the 2.5-m telescope of Caucasian Mountain Observatory of Sternberg Astronomical Institute Lomonosov Moscow State University in period 2022-2024 in different ambient conditions. The instrument was validated against Multi Aperture Scintillation Sensor. Using simultaneous observations with a speckle imager mounted at 2.5-m telescope, we demonstrate that dome OT power measured with Domecam can be converted into delivered image quality (DIQ) assuming von Karman model with outer scale of 0.57 +/- 0.1 m for dome turbulence. Dome turbulence increases median of expected distribution of DIQ for the 2.5-m telescope from 0.90'' to 1.12''.