  We report on the resistance behavior of bare-chip Cernox thermometers under
pressures up to 2 GPa, generated in a piston-cylinder pressure cell. Our
results clearly show that Cernox thermometers, frequently used in
low-temperature experiments due to their high sensitivity, remain highly
sensitive even under applied pressure. We show that these thermometers are
therefore ideally suited for measurements of heat capacity under pressure
utilizing an ac oscillation technique up to at least 150 K. Our Cernox-based
system is very accurate in determining changes of the specific heat as a
function of pressure as demonstrated by measurements of the heat capacity on
three different test cases: (i) the superconducting transition in elemental Pb
(T_{c} = 7.2 K), (ii) the antiferromagnetic transition in the rare-earth
compound GdNiGe3 (T_{N} = 26 K) and (iii) the structural/magnetic transition in
the iron-pnictide BaFe2As2 (T_{s,N} = 130 K). The chosen examples demonstrate
the versatility of our technique for measuring the specific heat under pressure
of various condensed matter systems with very different transition temperatures
as well as amounts of removed entropy.
