2018MNRAS.478.5683D

We have initiated a program to systematically observe lunar occultations from the SAO RAS 6-m telescope (BTA). So far, 25 events have been recorded with some of them leading to accurate measurements of angular diameters in late-type stars and of binary stars. One interesting aspect is that the observations are carried out by the same group and with the same equipment dedicated also to speckle interferometry, so that many of the target objects are being investigated by two independent and complementary techniques almost simultaneously. This represents a novel approach with a potential to provide more complete and extended results than possible until now. In this paper we focus on a general description of the scientific aim and methods, and we provide an overview of the results including an assessment of the quantitative performance, showing that milliarcsecond resolution is achieved on sources as faint as ≃12 mag. Among the sources we discuss in detail are the binary stars SAO 98270 and µ Cet, and the resolved late-type stars 74 Gem, DE Psc, and IRC+00213. Other stars with positive results are the subject of dedicated papers. We foresee to continue routine observations with this facility in the immediate future, and to coordinate with other observatories equipped with similar instrumentation.