# The Galactic extinction and reddening from the South Galactic Cap U-band Sky Survey: u band galaxy number counts and $u-r$ color distribution

## TL;DR

This study uses galaxy counts and color distributions from the SCUSS survey to measure Galactic extinction and reddening, comparing results with the SFD map and confirming the standard extinction law in low extinction regions.

## Contribution

It provides an independent assessment of Galactic extinction and reddening using galaxy data, revealing overestimation by SFD in high extinction areas and confirming the standard extinction law.

## Key findings

- Good agreement with SFD at low extinction regions
- SFD overestimates reddening in high extinction regions
- Extinction curve matches standard R_V=3.1 law

## Abstract

We study the integral Galactic extinction and reddening based on the galaxy catalog of the South Galactic Cap U-band Sky Survey (SCUSS), where $u$ band galaxy number counts and $u-r$ color distribution are used to derive the Galactic extinction and reddening respectively. We compare these independent statistical measurements with the reddening map of \citet{Schlegel1998}(SFD) and find that both the extinction and reddening from the number counts and color distribution are in good agreement with the SFD results at low extinction regions ($E(B-V)^{SFD}<0.12$ mag). However, for high extinction regions ($E(B-V)^{SFD}>0.12$ mag), the SFD map overestimates the Galactic reddening systematically, which can be approximated by a linear relation $\Delta E(B-V)= 0.43[E(B-V)^{SFD}-0.12$]. By combing the results of galaxy number counts and color distribution together, we find that the shape of the Galactic extinction curve is in good agreement with the standard $R_V=3.1$ extinction law of \cite{ODonnell1994}.