  WFPC2 images obtained with the Hubble Space telescope 4.16 years apart have
allowed us to measure the proper motion of the metal rich globular cluster NGC
6553 with respect to the background bulge stars. With a space velocity of
(${\Pi}, {\Theta}, W$) = (-3.5, 230, -3) km s$^{-1}$, NGC 6553 follows the mean
rotation of both disk and bulge stars at a Galactocentric distance of 2.7 kpc.
While the kinematics of the cluster is consistent with either a bulge or a disk
membership, the virtual identity of its stellar population with that of the
bulge cluster NGC6528 makes its bulge membership more likely. The astrometric
accuracy is high enough for providing a measure of the bulge proper motion
dispersion and confirming its rotation. A selection of stars based on the
proper motions produced an extremely well defined cluster color-magnitude
diagram (CMD), essencially free of bulge stars. The improved turnoff definition
in the decontaminated CMD confirms an old age for the cluster (~13 Gyr)
indicating that the bulge underwent a rapid chemical enrichment while being
built up at in the early Universe. An additional interesting feature of the
cluster color-magnitude diagram is a significant number of blue stragglers
stars, whose membership in the cluster is firmly established from their proper
motions.
