MISTRAL spectral coverage
CCD spectral response: Left: blue dispersor / blue lens (from Feige 15 observations). Right: red dispersor / red lens (from HR1544 observations). The dispersor (blue or red) has to be chosen before the beginning of the run in order for the right camera lens to be mounted. In principle this camera lens can also be changed (two lenses are available: blue and red). However, the lens can not be changed during the night because the operation has to be done by technical staff. The best that can be done is to change it during the day between two nights. And remember that a change of lens requires also to redo all the calibrations ! In order to measure the CCD spectral response, several standard spectrophotometric stars were observed. Figures below show the computed spectral response for the blue dispersor / blue lens (from Feige 15 observations) and for the red dispersor / red lens (from HR1544 observations).