An accurate new method of calculating absolute magnitudes and K-corrections applied to the Sloan filter set

This archive contains data in CSV format from Tables 2 to 6 of, "An accurate new method of calculating absolute magnitudes and K-corrections applied to the Sloan filter set", which has been submitted to the "Astrophysical Journal". The 10 tables list second order polynomial coefficients for use in determining absolute magnitudes from observed colors, two alternative colors being given for each of the Sloan u, g, r, i, z-bands, as described in the paper.We describe an accurate new method for determining absolute magnitudes, and hence also K-corrections, which is simpler than most previous methods, being based on a quadratic function of just one suitably chosen observed color. The method relies on the extensive and accurate new set of 129 empirical galaxy template SEDs from Brown et al. (2014). A key advantage of our method is that we can reliably estimate random errors in computed absolute magnitudes due to galaxy diversity, photometric error and redshift error. We derive K-corrections for the five Sloan Digital Sky Survey filters and provide parameter tables for use by the astronomical community. Using the New York Value-Added Galaxy Catalog we compare our K-corrections with those from kcorrect. Our K-corrections produce absolute magnitudes that are generally in good agreement with kcorrect. Absolute g, r, i, z-band magnitudes differ by less than 0.02 mag, and those in the u-band by ~0.04 mag. The evolution of rest-frame colors as a function of redshift is better behaved using our method, with relatively few galaxies being assigned anomalously red colors and a tight red sequence being observed across the whole 0.0 < z < 0.5 redshift range

本归档文件包含已投稿至《天体物理学杂志》（Astrophysical Journal）的论文《适用于斯隆滤光系统的绝对星等与K修正（K-corrections）计算的精确新方法》中表2至表6的CSV格式数据。该论文中的10张表格列出了二阶多项式系数，用于通过观测色指数计算绝对星等；针对斯隆u、g、r、i、z各波段，均提供了两种可选色指数，具体细节详见论文正文。

本文提出了一种精确的绝对星等与K修正计算新方法，该方法仅基于单个经恰当选取的观测色指数的二次函数，相较于多数现有方法更为简洁。本方法依托Brown等人2014年发表的一套包含129个经验星系模板的高精度光谱能量分布（Spectral Energy Distribution, SED）数据集。本方法的核心优势在于，能够可靠估算由星系多样性、测光误差与红移误差所引发的绝对星等计算随机误差。

我们针对斯隆数字巡天（Sloan Digital Sky Survey, SDSS）的五个滤镜波段推导了K修正，并为天文社区提供了配套参数表格。我们借助纽约增值星系目录（New York Value-Added Galaxy Catalog）将本文推导的K修正结果与kcorrect软件的计算结果进行了对比，结果显示二者所得绝对星等整体吻合良好：g、r、i、z波段的星等差异小于0.02星等，u波段差异约为0.04星等。

相较于现有方法，采用本文方法得到的静止帧色指数随红移的演化特性更为稳健；在0.0 < z < 0.5的全红移范围内，仅存在极少数星系被赋予反常偏红的色指数，且可观测到一条紧密的红序列。