We isolate a sample of 43 upper RGB stars in the extreme outer halo Galactic
globular cluster NGC 2419 from two Keck/DEIMOS slitmasks. The probability that
there is more than one contaminating halo field star in this sample is
extremely low. Analysis of moderate resolution spectra of these cluster
members, as well as of our Keck/HIRES high resolution spectra of a subsample of
them, demonstrates that there is a small but real spread in Ca abundance of ~
0.2 dex within this massive metal-poor globular cluster. This provides
additional support to earlier suggestions that NGC 2419 is the remnant of a
dwarf galaxy accreted long ago by the Milky Way.Comment: Accepted to the Astrophysical Journa
