The rotation curve ( RC ) of the Milky Way out to \sim 100 kpc has been constructed using \sim 16 , 000 primary red clump giants ( PRCGs ) in the outer disk selected from the LSS-GAC and the SDSS-III/APOGEE survey , combined with \sim 5700 halo K giants ( HKGs ) selected from the SDSS/SEGUE survey .
To derive the RC , the PRCG sample of the warm disc population and the HKG sample of halo stellar population are respectively analyzed using a kinematical model allowing for the asymmetric drift corrections and re-analyzed using the spherical Jeans equation along with measurements of the anisotropic parameter \beta currently available .
The typical uncertainties of RC derived from the PRCG and HKG samples are respectively 5 - 7 km s ^ { { -1 } } and several tens km s ^ { { -1 } } .
We determine a circular velocity at the solar position , V _ { c } ( R _ { 0 } ) = 240 \pm 6 km s ^ { -1 } and an azimuthal peculiar speed of the Sun , V _ { \odot } = 12.1 \pm 7.6 km s ^ { -1 } , both in good agreement with the previous determinations .
The newly constructed RC has a generally flat value of 240 km s ^ { -1 } within a Galactocentric distance r of 25 kpc and then decreases steadily to 150 km s ^ { -1 } at r \sim 100 kpc .
On top of this overall trend , the RC exhibits two prominent localized dips , one at r \sim 11 kpc and another at r \sim 19 kpc .
From the newly constructed RC , combined with other constraints , we have built a parametrized mass model for the Galaxy , yielding a virial mass of the Milky Way ’ s dark matter halo of 0.90 ^ { +0.07 } _ { -0.08 } \times 10 ^ { 12 } { M } _ { \odot } and a local dark matter density , \rho _ { \odot,dm } = 0.32 ^ { +0.02 } _ { -0.02 } GeV cm ^ { -3 } .