The goal was to achieve an accuracy of between 10 and 20% of a resolution element for the two gratings, with 10% for the LW grating as this is used in the Fabry-Pérot (FP) wavelength calibration.
These goals have been achieved, with the current wavelength accuracy being 1
LVDT (1/8 of a resolution element) in the SW grating section and between 0.5
and 1 LVDT in the LW section. Both FPs are accurate to about 
.
The wavelength calibration stabilisation is very good. A slight shift has been seen in the wavelength calibration between PV and rev 450 of about 3 LVDT (about half a resolution element at full grating resolution). This is corrected by updates of the relevant calibration files.