The Zero Point of Extinction toward Baade's Window from RR Lyrae Stars

We measure the zero point of the Stanek extinction map by comparing the observed ( V - K ) colors of 20 RR Lyrae stars (type ab ) found in the MACHO survey with their intrinsic ( V - K ) 0 colors as a function of period as determined from nearby RR Lyrae stars. We find that the zero point of the Stanek map should be changed by Δ A V = -0.11 ± 0.05 mag, in excellent agreement with the recent measurement of Gould, Popowski, & Terndrup using K giants.