Vector meson photoproduction offers the opportunity to image target nuclei. The two-dimensional Fourier transform $dsigma_{rm coherent}/dt$ of coherent vector meson photoproduction gives the two-dimensional distribution of interaction sites in the target. Since vector meson photoproduction occurs, at lowest order, via two-gluon exchange, this is sensitive to gluon shadowing. We present an analysis of $pi^+pi^-$ photoproduction using data from the STAR detector and a study of $dsigma_{rm coherent}/dt$, with an emphasis on probing the nuclear shape and its systematic uncertainties.
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