  The Pan-STARRS1 survey is acquiring multi-epoch imaging in 5 bands (grizy)
over the entire sky north of declination -30deg (the $3\pi$ survey). In July
2011 a test area of about 70 sq.deg. was observed to the expected final depth
of the main survey. In this, the first of a series of papers targetting the
galaxy count and clustering properties of the combined multi-epoch test area
data, we present a detailed investigation into the depth of the survey and the
reliability of the Pan-STARRS1 analysis software. We show that the Pan-STARRS1
reduction software can recover the properties of fake sources, and show good
agreement between the magnitudes measured by Pan-STARRS1 and those from Sloan
Digital Sky Survey. We also examine the number of false detections apparent in
the Pan-STARRS1 data. Our comparisons show that the test area survey is
somewhat deeper than the Sloan Digital Sky Survey in all bands, and, in
particular, the z band approaches the depth of the stacked Sloan Stripe 82
data.
