LOCS – LAMOST Open Cluster Survey

Why Open Clusters ? -- test-bed stellar evolution theory Galactic disc structure & evolution -- a lot more reasons …… (motivations)

Why LAMOST ? most efficiently: > 1 OCs/per night deep enough: V~15-16 to includ most of old OCs within d~10kpc Parameters R~10000 R V 1 km/s [Fe/H] 0.1dex For R~10000 ， V lim ~15; 30-40min. obs.  S/N~30 LAMOST’s ability Fibre n: ~ 4000 FOV: ~ 5 degree D= 4m Typical obs. area for an OC: 1d×1d with number of stars ~1000 (V~15)

 Critical constraints for Galactic structure & evolution scenarios What will be the output of LOCS ?  much reliable (kinematic) membership for cluster fields  more old and distant OCs with reliable kinematics & metallicity 6×10 2 OCs, each FOV ~ 1d×1d R V & [Fe/H] surveyed V ~ complete

>600 OCs selected(zenith< 60d ) for LOCS FOV of LAMOST

Sample OC distribution near the disc

~ From total of ~600 OCs N~350N~300N~70 Observed Rgc,age,[Fe/H] for the selected sample

Summary Rv & metallicity of GOCS are very important. Of course. LAMOST could be very efficient in spectroscopic OC survey LOCS aims to produce a homogeneous Rv & metallicity dataset for about 600 OCs, with limiting magnitude to 15 or 16, with, say, 2 years observation run This dataset would be of great importance for researches on Galactic structure & evolution