First results from the Pristine CaHK survey with CFHT/MegaCam
Nicolas Martin

I will present the first results of the Pristine survey, a Franco-Canadian photometric survey of the Milky Way halo performed with the new CaHK filter on CFHT's MegaCam. Currently covering ~1,000 deg2, this survey leads to an efficient metallicity decomposition of the Milky Way halo. In particular, I will show how efficient Pristine is in selecting the metal-poor end of the metallicity distribution ([Fe/H] < -2.5) to hunt for the very rare extremely metal-poor stars (bearer of the chemical imprint of the first stars). A dedicated part of the survey also focuses on the enigmatic very faint (and therefore metal-poor) Milky Way dwarf galaxies found over the last decade. I will show how efficient Pristine is at isolating likely member stars and how it opens a well-needed window onto the detailed study of these systems, often used as near-field cosmological probes. Our spectroscopic follow-up is just starting but already shows a very promising efficient at selecting very metal-poor stars from our photometry alone.