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

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 the Caucasian Mountain Observatory of the Sternberg Astronomical Institute, Lomonosov Moscow State University, in the period 2022 to 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 Kármán 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″.