The PPM catalog was extracted using XCATSCAN and divided up into
2mass scan-like strips 8 degrees long (the shortest scan in
the current survey strategy) and 8
wide. As of now, only the
northern hemisphere has been used, which was picked because
the northern hemisphere is the lowest density, most non-uniform
part of the PPM).
The results for the number of scans in the Northern Hemisphere
with a given number of PPM stars:
