FOCAS IFU: Wavelength Coverage

In FOCAS IFU data, the wavelength coverage varies from channel to channel mainly because of the vignettings by FOCAS main optics.

Location of each channel in the fits image.

Followings are plots of CAL Halogen Lamp spectrum normalized by the spectrum at the field center, channel 12.

From these plots, you can check the wavelength coverage of each channel for a specific grism setting. The data are not flat-fielded, so fluctuations can be seen in the normalized spectra.

In the short wavelength side, the normalized spectra are very noisy due to poor S/N.

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