This is the instrument performance plot for the quality of the dispersion
solution of GIRAFFE.
There are five different fibre systems: Medusa1/2, IFU1/2, and
Argus, and two different gratings, HR and LR. For the HR grating, we display
the rms of the residuals of the accepted line
positions against the dispersion
solution, rms_fit (PRO.WSOL.RMS). 
HC data are taken
every 3 days for the Medusa slits, and every 7 days for the IFU/Argus slits.
The monitoring is done in the H525.8B setting for the HR grating and L543.1
for the LR grating. For the LR grating,
only the two Medusa settings are taken.
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While the rms parameter describes the accuracy of the achieved wavelength
solution, there is no documented reference value for it. We have decided to
mark the best observed value for each fibre system, considering a reasonable
uncertainty of the measurements. This uncertainty is particularly high for the LR values.</font><p><font size="2">

Some of the values for early epochs (until 2005) 
have been reprocessed with the current pipeline (giraf-2.5 and higher), they are displayed as
separate
datasets as indicated in plots #1, #2, #6, and #7. They do not show systematic
differences.
The observed
degradation in the HR resolution, in particular between 2013 and 2015 was real. It was successfully remedied by an
intervention, with the values being more stable and close to their optimal level since then.</font><p><font size="2">

The difference between the HR Medusa1/2 and the IFU/Argus slits is due to
different fibre diameters (higher resolution, fewer blends).