Mobile Differential Image Motion Monitor for Astroclimate Research

Abstract

A differential image motion monitor (DIMM) has been developed and manufactured to study atmospheric seeing. The monitor is made in a lightweight field version and can operate without a telescope, as has always been the case before. Two apertures are made using 70-mm lenses with a focal distance of 900 mm. The distance between the aperture axes is 300 mm. The images from the apertures are combined in the plane of a single CMOS camera operating at up to 314 frames per second speed with low reading noise of about \(3e^{-}\). The device also includes a \(3^{\circ}\!\times\!3^{\circ}\) field of view viewer for pointing at a star. The monitor proved to work successfully during several astroclimate study expeditions. The monitor data were verified by comparing them with the results of atmospheric seeing measurements at the 2.5 meter telescope of the Caucasian Mountain Observatory.