Accurate determinations of atmospheric parameters ( effective temperature T _ { eff } , surface gravity log g and metallicity [ Fe/H ] ) and distances for large complete samples are of vital importance for various Galactic studies .
We have developed a photometric method to select red giant stars and estimate their atmospheric parameters from the photometric colors provided by the SkyMapper Southern Survey ( SMSS ) data release ( DR ) 1.1 , using stars in common with the LAMOST Galactic spectroscopic surveys as a training set .
Distances are estimated with two different approaches : one based on the Gaia DR2 parallaxes for nearby ( d \leq 4.5 kpc ) bright stars and another based on the absolute magnitudes predicted by intrinsic color ( g - i ) _ { 0 } and photometric metallicity [ Fe/H ] for distant ( d > 4.5 kpc ) faint stars .
Various tests show that our method is capable of delivering atmospheric parameters with a precision of \sim 80 K for T _ { eff } , \sim 0.18 dex for [ Fe/H ] and \sim 0.35 dex for log g but with a significant systematic error at log g \sim 2.3 .
For distances delivered from ( g - i ) _ { 0 } and photometric [ Fe/H ] , our test with the member stars of globular clusters show a median uncertainty of 16 per cent with a negligible zero-point offset .
Using this method , atmospheric parameters and distances of nearly one million red giant stars are derived from SMSS DR1.1 .
Proper motion measurements from Gaia DR2 are available for almost all of the red giant stars , and radial velocity measurements from several large spectroscopic surveys are available for 44 per cent of these .
This sample will be accessible online at https : //yanghuang0.wixsite.com/yangh/research .