After the wavelength calibration is obtained from an LSS arc lamp
exposure, the wavelength corresponding to the central CCD pixel is
calculated. The values trended here are for the blue sensitive EEV
detector, the 300V grism with no filter and a slit width of 0.29".

More information can be found on
the <a href="http://www.eso.org/observing/dfo/quality/FORS2/qc/lsswlc/lsswlc.html">plot tutorial page</a>