In 1990 I published a study of the Kitt Peak night sky using absolute spectrophotometry (Massey, Gronwall, & Pilachowski 1990 PASP, 102, 1046) . About 10 years later, Craig Foltz and I revisted the issue (Massey & Foltz 2000 PASP, 112, 566) . Typical night-sky spectra can be found at here for the blue and here for the red.
E-mail: massey (at) lowell.edu