Evidence for a Milky Way Tidal Stream Reaching Beyond 100 kpc
  We present the analysis of 1,207 RR Lyrae found in photometry taken by the
Catalina Survey's Mount Lemmon telescope. By combining accurate distances for
these stars with measurements for ~14,000 type-AB RR Lyrae from the Catalina
Schmid telescope, we reveal an extended association that reaches Galactocentric
distances beyond 100 kpc and overlaps the Sagittarius streams system. This
result confirms earlier evidence for the existence of an outer halo tidal
stream resulting from a disrupted stellar system. By comparing the RR Lyrae
source density with that expected based on halo models, we find the detection
has ~8 sigma significance. We investigate the distances, radial velocities,
metallicities, and period-amplitude distribution of the RR Lyrae. We find that
both radial velocities and distances are inconsistent with current models of
the Sagittarius stream. We also find tentative evidence for a division in
source metallicities for the most distant sources. Following prior analyses, we
compare the locations and distances of the RR Lyrae with photometrically
selected candidate horizontal branch stars and find supporting evidence that
this structure spans at least 60 deg of the sky. We investigate the prospects
of an association between the stream and unusual globular cluster NGC 2419.
