  The wavelength calibration of spectrographs is an essential but challenging
task in many disciplines. Calibration is traditionally accomplished by imaging
the spectrum of a light source containing features that are known to appear at
certain wavelengths and mapping them to their location on the sensor. This is
typically required in conjunction with each scientific observation to account
for mechanical and optical variations of the instrument over time, which may
span years for certain projects. The method presented here investigates the
usage of color itself instead of spectral features to calibrate a spectrograph.
The primary advantage of such a calibration is that any broad-spectrum light
source such as the sky or an incandescent bulb is suitable. This method allows
for calibration using the full optical pathway of the instrument instead of
incorporating separate calibration equipment that may introduce errors. This
paper focuses on the potential for color calibration in the field of radial
velocity astronomy, in which instruments must be finely calibrated for long
periods of time to detect tiny Doppler wavelength shifts. This method is not
restricted to radial velocity, however, and may find application in any field
requiring calibrated spectrometers such as sea water analysis, cellular
biology, chemistry, atmospheric studies, and so on. This paper demonstrates
that color sensors have the potential to provide calibration with greatly
reduced complexity.
