Near IR Spectra
In Figure 2 we compare the NIR sky spectrum obtained at a ALT=15, AZ=30 (red line) toward La Serena and at ALT=15, AZ=220.
Two conclusions can be drawn from the spectra:
No artificial emission line is detectable in the direction of La Serena but only a very weak increase in the thermal background.
The increase of the background toward the North is mostly due to the OH emission lines. This is consistent with the fact that the maximum is higher in the H band where the OH lines are stronger.