  The results obtained using the temperature monitoring systems of the 6-m BTA
telescope primary mirror, dome space, and external environment are reported. We
consider the factors that affect the development of microturbulence in the
near-mirror air layer and inside the dome space, variation of the telescope
focal length with the temperature of its structures, variation of seeing due to
temperature gradients inside the primary mirror of the 6-m telescope. The
methods used in various observatories for reducing microturbulence are
analyzed. We formulate suggestions concerning the improvement of the
temperature monitoring system currently in operation and the system of
automatic adjustment of the telescope focal length to compensate the thermal
drift of the focus during observations.

Instrumentation and Methods for Astrophysics