spatial position in the image, and found that it was negligible for a $3\arcsec$ aperture. These corrections were typically on the order of 15%, or $-0.18$ mag. The $3\arcsec$ aperture was the best compromise between signal-to-noise, and the desire for the aperture correction to not vary significantly across the field-of-view. SExtractor detected objects on a summed $V+R$ image, and measured fluxes through the same apertures in all five bands.

Together in the three fields, we compiled a catalog of $56,674$ unique objects with good photometry—objects not corrupted by saturation, bleed trails, or edge effects—and $V<23$.

Comparison with Published Catalogs
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While there have been many published photometric studies of this region, one of the most useful comparisons is with the VLT measurements of probable GCs in Rejkuba (2001). There are 78 objects for comparison in $U$ and $V$, 75 of which we detect (the remaining three were likely too faint). The $V$ photometry is well-behaved, as the errors are small for both studies. The median offsets between the Rejkuba and Mosaic photometry are small ($\sim0.03$ mag), although the RMS scatter ($\sim0.27$ mag) is higher than expected by about a factor of two. The $U$ is less consistent because our Mosaic 