  We present an updated and improved description of the light curve behaviour
of T Ursae Minoris, which is a Mira star with the strongest period change (the
present rate is an amazing -3.8+/-0.4 days/year corresponding to a relative
decrease of about 1% per cycle). Ninety years of visual data were collected
from all available databases and the resulting, almost uninterrupted light
curve was analysed with the O-C diagram, Fourier analysis and various
time-frequency methods. The Choi-Williams and Zhao-Atlas-Marks distributions
gave the clearest image of frequency and light curve shape variations. A
decrease of the intensity average of the light curve was also found, which is
in accordance with a period-luminosity relation for Mira stars. We predict the
star will finish its period decrease in the meaningfully near future (c.c. 5 to
30 years) and strongly suggest to closely follow the star's variations
(photometric, as well as spectroscopic) during this period.
