  Recent work on Ultra Long Period Cepheids (ULPCs) has suggested their
usefulness as a distance indicator, but has not commented on their relationship
as compared with other types of variable stars. In this work, we use Fourier
analysis to quantify the structure of ULPC light curves and compare them to
Classical Cepheids and Mira variables. Our preliminary results suggest that the
low order Fourier parameters of ULPCs show a continuous trend defined by
Classical Cepheids after the resonance around 10 days. However their Fourier
parameters also overlapped with those from Miras, which make the classification
of long period variable stars difficult based on the light curves information
alone.
