This data set contains the Magellan Compressed Thrice Mosaicked Image Data Records (C3-MIDRs) which consists of mosaics generated by computing 3x3 pixel arithmetic moving averages from the C2-MIDRs. Each C3-MIDR is in a sinusoidal equal area projection and has an origin at 0 degrees latitude, with the central meridian defined as the longitude bisecting the mosaic. Each C1-MIDR has 7168 lines (aligned with latitudes) and 8192 samples, arranged as 56 1024 x 1024 files on CD-ROM. C3-MIDRs, with their 2.025 km pixel widths, are designed to cover the planet at reasonably high resolution and high signal to noise ratio. The 1024 x 1024 files have a VICAR2 format, with embedded VICAR2 labels. The data have been placed on CD-ROMs with documentation, detached Planetary Data System labels, and summary tabular information.