Several site-testing programs and observatories currently use combined MASS-DIMM instruments for monitoring parameters of optical turbulence. The instrument is described here. After a short recall of the measured quantities and operational principles, the optics and electronics of MASS-DIMM, interfacing to telescopes and detectors, and operation are covered in some detail. Particular attention is given to the correct measurement and control of instrumental parameters to ensure valid and well-calibrated data, to the data quality and filtering. Examples of MASS-DIMM data are given, followed by the list of present and future applications.
@article{arxiv.0709.2081,
title = {Combined MASS-DIMM instrument for atmospheric turbulence studies},
author = {V. Kornilov and A. Tokovinin and N. Shatsky and O. Voziakova and S. Potanin and B. Safonov},
journal= {arXiv preprint arXiv:0709.2081},
year = {2009}
}