The PIPER Survey: I. An Initial Look at the Intergalactic Globular
  Cluster Population in the Perseus Cluster
  We describe the goals and first results of a Program for Imaging of the
PERseus cluster of galaxies (PIPER). The first phase of the program builds on
imaging of fields obtained with the Hubble Space Telescope (HST) ACS/WFC and
WFC3/UVIS cameras. Our PIPER target fields with HST include major early-type
galaxies including the active central giant NGC 1275; known Ultra-Diffuse
Galaxies; and the Intracluster Medium. The resulting two-color photometry in
F475W and F814W reaches deep enough to resolve and measure the globular cluster
(GC) populations in the Perseus member galaxies. Here we present initial
results for eight pairs of outer fields that confirm the presence of
Intergalactic GCs (IGCs) in fields as distant as 740 kpc from the Perseus
center (40\% of the virial radius of the cluster). Roughly 90% of these IGCs
are identifiably blue (metal-poor) but there is a clear trace of a red
(metal-rich) component as well, even at these very remote distances.
