Abstract
We have determined the ratios of total to selective extinction directly from observations in the optical V band and near-infrared J band toward the Galactic center. The OGLE (Optical Gravitational Lensing Experiment) Galactic bulge fields have been observed with the SIRIUS camera on the Infrared Survey Facility telescope, and we obtain AV/EV–J = 1.251 ± 0.014 and AJ/EV–J = 0.225 ± 0.007. From these ratios, we derive AJ/AV = 0.188 ± 0.005; combining this with the near-infrared extinction ratios obtained in Paper I for more reddened fields near the Galactic center, we obtain AV:AJ:AH:AKs = 1:0.188:0.108:0.062, which implies steeply declining extinction toward longer wavelengths. In particular, it is striking that the Ks-band extinction is ≈1/16 the visual extinction AV, much smaller than the 1/10 usually employed.
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