  We present deep V,I CCD photometry of the globular cluster Terzan 8, recently
found to be a member of the globular cluster system of the Sagittarius dwarf
spheroidal galaxy. We accurately estimate the metallicity of Ter 8 and provide
the first direct determination of the color excess toward this cluster. Our
robust age estimate confirms that this cluster is indeed coeval with typical
galactic globulars of comparable metal content, and thus it is probably
significantly older than at least two other Sagittarius clusters, Terzan 7 and
Arp 2. The implications of this result on the star formation history of the
Sagittarius galaxy are briefly discussed.
