Spatial variations of galaxy number counts in the Sloan Digital Sky Survey. II. Test of galactic extinction in high-extinction regions

Galactic extinction is tested using galaxy number counts at low Galactic latitude obtained from five-band photometry of the Sloan Digital Sky Survey. The spatial variation of galaxy number counts for low-extinction regions of E(B-V) < 0.15 is consistent with the all-sky reddening map of Schlegel and coworkers and the standard extinction law. For higher extinction regions of E(B-V) > 0.15, however, the map of Schlegel and coworkers overestimates the reddening by a factor of up to 1.4, which can likely be ascribed to the departure from proportionality of reddening to infrared emissivity of dust. This result is consistent with the analysis of Arce & Goodman for the Taurus dark cloud complex.