HST image of Palomar 4. This is the average of 7x1400 seconds in F555W added to the average of 9x1300 seconds in F814W

Up to now ('now' is ~1996) precise relative ages have only been determined for those globular clusters within about 10 kpc of the Sun. Only via dubious indirect methods have we inferred the ages for clusters at very large and very small Galactocentric radii. We don't yet know the answer to a question as fundamental as 'did the Galaxy from from the outside in or inside out'.

I am a member of a team using HST in Cycles 4 through 7 to estimate ages of 6 clusters in the distant halo of the Galaxy, NGC 2419, Pal 3, Pal 4, Pal 14, AM-1 and Eridanus. After spending too long learning the ins-and-outs of doing accurate photometry on WFPC2 frames, we are almost ready to announce our first results.