Wavelength calibration of GMOS spectra is usually based on CuAr spectra. This page provides plots of CuAr spectra obtained with GMOS. The raw data from GMOS has long wavelengths (red) to the left and short wavelengths (blue) to the right. The spectra shown here have been calibrated and therefore have short wavelengths to the left and long wavelengths to the right.

The CuAr linelist supplied with the standard IRAF distribution will provide good wavelength calibrations. A custom CuAr linelist is also distributed with the Gemini IRAF package.