We present the results of a deep , wide-area variability survey in the Southern hemisphere , the first of its kind .
As part of the Catalina Sky Surveys , the Siding Spring Survey ( SSS ) has covered 14 , 800 square degrees in the declination range of -75 ^ { \circ } \leq \delta \leq - 15 ^ { \circ } .
To mine the enormous SSS dataset efficiently we have developed two algorithms : Automatic Period Selection ( APS ) and Automatic Fourier Decomposition ( AFD ) , which aim to sharpen the period estimation and produce robust lightcurve models .
Armed with the APS and AFD outputs we classify 10 , 540 ab-type RR Lyrae ( RRab ) stars ( \sim 90 % of which are new ) across the Southern sky .
As well as the positional information we supply photometric metallicities , and unreddened distances .

For the RRab stars in the halo , a study of the photometric metallicity distribution reveals a nearly Gaussian shape with a mean metallicity of { [ Fe / H ] } = -1.4 dex and a dispersion of 0.3 dex .
A spatial study of the RRab metallicities shows no significant radial gradient in the first \sim 7 kpc from the Galaxy center .
However , further out , a small negative gradient is clearly present .
This is complemented by a very obvious correlation of the mean RR Lyrae metallicity with distance above the Galactic plane , z .
We have also carried out an initial substructure search using the discovered RRab , and present the properties of the candidates with significance greater than 2 ~ { } \sigma .
Most prominent among these is a southern extension of the Sagittarius dwarf galaxy ’ s stream system , reaching down to declinations \sim - 40 \deg .