We present a catalog of RR Lyrae stars ( RRLs ) observed by the Xuyi Schmidt Telescope Photometric Survey ( XSTPS ) .
The area we consider is located in the North Galactic Cap , covering \approx 376.75 ~ { } \mathrm { deg } ^ { 2 } at \alpha \approx 150 ~ { } \mathrm { deg } and \delta \approx 27 ~ { } \mathrm { deg } down to a magnitude limit of i \approx 19 .
Using the variability information afforded by the multi-epoch nature of our XSTPS data , combined with colors from the Sloan Digital Sky Survey , we are able to identify candidate RRLs .
We find 318 candidates , derive distances to them and estimate the detection efficiency .
The majority of our candidates have more than 12 observations and for these we are able to calculate periods .
These also allows us to estimate our contamination level , which we predict is between 30 % to 40 % .
Finally we use the sample to probe the halo density profile in the 9 - 49 ~ { } \mathrm { kpc } range and find that it can be well fitted by a double power law .
We find good agreement between this model and the models derived for the South Galactic Cap using the Watkins et al .
( 51 ) and Sesar et al .
( 40 ) RRL data-sets , after accounting for possible contamination in our data-set from Sagittarius stream members .
We consider non-spherical double power law models of the halo density profile and again find agreement with literature data-sets , although we have limited power to constrain the flattening due to our small survey area .
Much tighter constraints will be placed by current and future wide-area surveys , most notably ESA ’ s astrometric Gaia mission .
Our analysis demonstrates that surveys with a limited number of epochs can effectively be mined for RRLs .
Our complete sample is provided as accompanying online material .