  We present a long temporal baseline variability survey in the Frontier Field
MACSJ1149. In this study, we identify active galactic nuclei (AGNs) and other
transient sources via their variability using over a decade of Hubble Space
Telescope (HST) images for thousands of galaxies in the cluster region and
detect significant variability in galaxies extending down to an apparent
nuclear magnitude of m$_{i}$ $<$ 26.5. Our analysis utilizes HST images
obtained in six different wavelengths from 435 nm to 1.6 microns and covers
time scales 12 hours to 12 years apart. We find that $\sim$2% of galaxies in
these images are variable with 49 AGN candidates and 4 new supernovae
candidates detected. Half of the variables are in the cluster and these are
primarily elliptical galaxies displaying variability only in the near-infrared
bands. About 20% of the AGN candidates have morphologies and colors consistent
with quasars, though most of the variables appear to be dominated by the host
galaxy light. The structure function for these sources show a greater amplitude
of variability at shorter wavelengths with slopes shallower than typical
quasars. We also report a previously unknown Einstein cross identified in this
field.
