Metal-poor stars are important tools for tracing the early history of the Milky Way , and for learning about the first generations of stars .
Simulations suggest that the oldest metal-poor stars are to be found in the inner Galaxy .
Typical bulge surveys , however , lack low metallicity ( [ Fe / H ] < -1.0 ) stars because the inner Galaxy is predominantly metal-rich .
The aim of the Pristine Inner Galaxy Survey ( PIGS ) is to study the metal-poor and very metal-poor ( VMP , [ Fe / H ] < -2.0 ) stars in this region .
In PIGS , metal-poor targets for spectroscopic follow-up are selected from metallicity-sensitive CaHK photometry from the CFHT .
This work presents the \sim 250 deg ^ { 2 } photometric survey as well as intermediate-resolution spectroscopic follow-up observations for \sim 8000 stars using AAOmega on the AAT .
The spectra are analysed using two independent tools : ULySS with an empirical spectral library , and FERRE with a library of synthetic spectra .
The comparison between the two methods enables a robust determination of the stellar parameters and their uncertainties .
We present a sample of 1300 VMP stars – the largest sample of VMP stars in the inner Galaxy to date .
Additionally , our spectroscopic dataset includes \sim 1700 horizontal branch stars , which are useful metal-poor standard candles .
We furthermore show that PIGS photometry selects VMP stars with unprecedented efficiency : 86 % /80 % ( lower/higher extinction ) of the best candidates satisfy [ Fe / H ] < -2.0 , as do 80 % /63 % of a larger , less strictly selected sample .
We discuss future applications of this unique dataset that will further our understanding of the chemical and dynamical evolution of the innermost regions of our Galaxy .