[Fe/H] as a function of angular distance from the main body of Sgr along the leading arm (left panels) and trailing arm (right panels). The upper panels show the individual points. In the lower panels, the distribution of [Fe/H] is displayed as the median. The solid line shows the result of a least-squares linear fit to the median data. The metallicity gradient is −(1.5 ± 0.4)× 10 ⁻³ dex deg ⁻¹ in leading arm 1 and −(1.8 ± 0.3)× 10 ⁻³ dex deg ⁻¹ in trailing arm 1. The fitted line shows that the metallicity is nearly flat in leading arm 2 and trailing arm 2.