We propose and test a method for applying statistical photometric parallax to main sequence turn off ( MSTO ) stars in the Sloan Digital Sky Survey ( SDSS ) .
Using simulated data , we show that if our density model is similar to the actual density distribution of our data , we can reliably determine the density model parameters of three major substructures in the Milky Way halo using the computational resources available on MilkyWay @ home ( a twenty parameter fit ) .
We fit the stellar density in SDSS stripe 19 with a smooth stellar spheroid component and three major streams .
One of these streams is consistent with the Sagittarius tidal stream at 21.1 kpc away , one is consistent with the trailing tail of the Sagittarius tidal stream in the north Galactic cap at 48 kpc away , and one is possibly part of the Virgo Overdensity at 6 kpc away .
We find the one sigma widths of these three streams to be 1.0 kpc , 17.6 kpc , and 6.1 kpc , respectively .
The width of the trailing tail is extremely wide ( 41 kpc full width at half maximum ) .
This large width could have implications for the shape of the Milky Way dark matter halo .
The width of the Virgo Overdensity-like structure is consistent with what we might expect for a “ cloud ” -like structure ; analysis of additional stripes of data are needed to outline the full extent of this structure and confirm its association with the Virgo Overdensity .