  High-resolution temperature measurements are required in the LTP, i.e., 10
uK/sqrt(Hz) from 1 mHz to 30 mHz. This has been already accomplished with
thermistors and a suitable low noise electronics. However, the frequency range
of interest for LISA goes down to 0.1 mHz. Investigations on the performance of
temperature sensors and the associated electronics at frequencies around 0.1
mHz have been performed. Theoretical limits of the temperature measurement
system and the practical on-ground limitations to test them are shown
demonstrating that 1/f noise is not observed in thermistors even at frequencies
around 0.1 mHz and amplitude levels of 10 uK/sqrt(Hz).
