These are the USNO40 response curves that define the u'g'r'i'z'
standard system, along with the standard stars of Smith et al. (2002,
AJ, 123, 2121).

Zeropoints are defined as an offset from an AB system. See readme.txt
note from Jim Gunn. We're using the 1.3 airmass column to define the
system (like Smith et al.).

Note -- this is NOT the SDSS 2.5m photometric system! That system is
calibrated to the same standard stars, but has a different response.

Files downloaded from http://www-star.fnal.gov/ugriz/Filters/response.html
