Apparent Trend of the Iron Abundance in NGC 3201: the Same Outcome with
  Different Data
  We further study the unusual trend we found at statistically significant
levels in some globular clusters, including NGC 3201: a decreasing iron
abundance in red giants towards the cluster centers. We first show that
recently published new estimates of iron abundance in the cluster reproduce
this trend, in spite of the authors' statement about no metallicity spread due
to a low scatter achieved in the [FeII/H] ratio. The mean of [FeII/H] within $R
\sim 2'$ from the cluster center is lower, by $\Delta$[FeII/H] = 0.05$\pm$0.02
dex, than in the outer region, in agreement with our original estimate for a
much larger sample size within $R \approx 9'$. We found that an older dataset
traces the trend to a much larger radial distance, comparable with the cluster
tidal radius, at $\Delta$[Fe/H]$\sim$0.2 dex due to higher metallicity of
distant stars. We conclude the trend is reproduced by independent datasets and
find that it is accompanied with both a notable same-sign trend of oxygen
abundance which can vary by up to $\Delta$[O/Fe]$\sim$0.3 dex within $R \approx
9'$, and opposite-sign trend of sodium abundance.
