  We extend the technique originally proposed by Honda et al.to measure the
temperature of Ytterbium and alkine-earth atoms confined in a Magneto-Optical
Trap (MOT). The method is based on the analysis of excitation spectra obtained
by probing the 1S0->3P1 inter-combination line. Thanks to a careful analysis
and modeling of the effects caused by the MOT light on the probe transition we
overcome the resolution and precision limits encountered in previous works.
Ground state light shift and Rabi broadening are measured and successfully
compared with calculated values. This knowledge allows us to properly extract
the Doppler contribution to the linewidth, thus obtaining a reliable
measurement of the cloud temperature. We finally show how spectroscopy on
free-falling atoms provides an alternative method to determine the sample
temperature which resembles the standard time-of-flight technique.
