(The following is an excerpt from the introduction of the MODIS-CON - Description and Interface Control Document. The complete document can be found at the CloudSat Standard Data Product Interface Control Document links page. )
Because of the significant data volume associated with the AN-MODIS product, a special hybrid auxiliary product is produced that is identical to the AN-MODIS data format, but has been extracted to be centered on the CloudSat subtrack and +/- 35km from that track.
This product differs from the MODIS-AUX in that the MODIS data are not sampled to match each CloudSat profile point (thus no data overlaps) but, instead, the MODIS data are simply extracted to produce a 71-km wide swath centered on the CloudSat ground track.
These data are used a "context" to assist in the interpretation of the larger scale cloud fields that CloudSat is sampling - thus the "-CON" suffix on the data files.
Also see the CloudSat Data I/O Interface Specifications