We use Canada - France - Hawaii Telescope Legacy Survey data for 170 deg ^ { 2 } , recalibrated and transformed to the Sloan Digital Sky Survey ugri photometric system , to study the distribution of near-turnoff main-sequence stars in the Galactic halo along four lines of sight to heliocentric distances of \sim 35 kpc .
We find that the halo stellar number density profile becomes steeper at Galactocentric distances greater than R _ { gal } \sim 28 kpc , with the power law index changing from n _ { inner } = -2.62 \pm 0.04 to n _ { outer } = -3.8 \pm 0.1 .
In particular , we test a series of single power law models and find them to be strongly disfavored by the data .
The parameters for the best-fit Einasto profile are n = 2.2 \pm 0.2 and R _ { e } = 22.2 \pm 0.4 kpc .
We measure the oblateness of the halo to be q \equiv c / a = 0.70 \pm 0.01 and detect no evidence of it changing across the range of probed distances .
The Sagittarius stream is detected in the l = 173 \arcdeg and b = -62 \arcdeg direction as an overdensity of { [ Fe / H ] } \sim - 1.5 dex stars at R _ { gal } \sim 32 kpc , providing a new constraint for the Sagittarius stream and dark matter halo models .
We also detect the Monoceros stream as an overdensity of { [ Fe / H ] } > -1.5 dex stars in the l = 232 \arcdeg and b = 26 \arcdeg direction at R _ { gal } \lesssim 25 kpc .
In the two sightlines where we do not detect significant substructure , the median metallicity is found to be independent of distance within systematic uncertainties ( { [ Fe / H ] } \sim - 1.5 \pm 0.1 dex ) .