  The globular cluster ultraluminous X-ray source, RZ2109, is a complex and
unique system which has been detected at X-ray, ultra-violet, and optical
wavelengths. Based on almost 20 years of Chandra and XMM-Newton observations,
the X-ray luminosity exhibits order-of-magnitude variability, with the peak
flux lasting on the order of a few hours. We perform robust time series
analysis on the archival X-ray observations and find that this variability is
periodic on a timescale of 1.3 $\pm 0.04$ days. The source also demonstrates
broad [OIII] 5007 Angstrom emission, which has been observed since 2004,
suggesting a white dwarf donor and therefore an ultra-compact X-ray binary. We
present new spectra from 2020 and 2022, marking eighteen years of observed
[OIII] emission from this source. Meanwhile, we find that the globular cluster
counterpart is unusually bright in the NUV/UVW2 band. Finally, we discuss
RZ2109 in the context of the eccentric Kozai Lidov mechanism and show that the
observed 1.3 day periodicity can be used to place constraints on the tertiary
configuration, ranging from 20 minutes (for a 0.1 ${\rm M}_\odot$ companion) to
approximately 95 minutes (for a 1 ${\rm M}_\odot$ companion), if the eccentric
Kozai Lidov mechanism is at the origin of the periodic variability.
