Improved compositions, methods, apparatus, and kits for high-throughput nucleic acid amplification, detection and sequencing are disclosed. A nucleic acid cluster having an identifiable center is produced by generating on a solid support an immobilized nucleic acid complement from a template, one of which comprises a detectable label; and amplifying the complement and the template to obtain a nucleic acid cluster on the support, the cluster having a substantially central location marked by the detectable label and a surrounding region comprising immobilized copies. Also disclosed are nucleotide sequence determination in nucleic acid clusters so produced, center position annotation in the clusters, assignment of sequence information to overlapping clusters, and related compositions and methods.