, J.--F. Panis
, C. Thum
IRAM (Grenoble)
IRAM (Granada) 
(rms) which, however, degrades
slowly with time. Application by the observer of instantaneous
pointing corrections recovers the inherently precise operation of the
telescope.
The data analyzed here show that the number of pointing parameters used for the 30--m telescope can be reduced to six because the astronomical positions of pointing sources are today accurately known, and because the telescope does not show hysteresis or long--term irreversible changes of its mechanical behaviour so that the gravitational bending can be described by a unique and time--independent function, as should be the case.
There are indications that the inclination of the azimuth axis is
influenced by seasonal thermal effects, which merit further
monitoring for eventual quasi real time correction. The other
pointing parameters show random variations in time which makes it
difficult to trace any particular source which sets their ultimate
accuracy, although we suspect residual thermal effects to be the main
source of perturbation.