We present the first definitive measurement of the absolute magnitude of RR Lyrae c-type variable stars ( RRc ) determined purely from statistical parallax .
We use a sample of 247 RRc selected from the All Sky Automated Survey ( ASAS ) for which high-quality light curves , photometry and proper motions are available .
We obtain high-resolution echelle spectra for these objects to determine radial velocities and abundances as part of the Carnegie RR Lyrae Survey ( CARRS ) .
We find that M _ { V, RRc } = 0.52 \pm 0.11 at a mean metallicity of { [ Fe / H ] } = -1.59 .
This is to be compared with previous estimates for RRab stars ( M _ { V, RRab } = 0.75 \pm 0.13 ) and the only direct measurement of an RRc absolute magnitude ( RZ Cephei , M _ { V,RRc } = 0.27 \pm 0.17 ) .
We find the bulk velocity of the halo to be ( W _ { \pi } ,W _ { \theta } ,W _ { z } ) = ( 10.9 , 34.9 , 7.2 ) { km s } ^ { -1 } in the radial , rotational and vertical directions with dispersions ( \sigma _ { W _ { \pi } } , \sigma _ { W _ { \theta } } , \sigma _ { W _ { z } } ) = ( 154.7 , 103.6 , 93.8 ) { km% s } ^ { -1 } .
For the disk , we find ( W _ { \pi } ,W _ { \theta } ,W _ { z } ) = ( 8.5 , 213.2 , -22.1 ) { km s } ^ { -1 } with dispersions ( \sigma _ { W _ { \pi } } , \sigma _ { W _ { \theta } } , \sigma _ { W _ { z } } ) = ( 63.5 , 49.6 , 51.3 ) { km% s } ^ { -1 } .
Finally , we suggest that UCAC2 proper motion errors may be overestimated by about 25 % .