This is the instrument performance plot for the GIRAFFE
resolution. 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 resolving power 
R =
&lambda;<sub>0</sub>/&Delta;&lambda;. &Delta;&lambda; is the QC1 
parameter mean_resol (QC.RESOL.MEAN)
which is the mean of all accepted emission line widths. 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.
</font><p><font size="2">

The 
reference values are marked in green.</font><p><font size="2">

The HR values for the first years (until 2007), when calculated with the then
available
pipeline versions, were systematically wrong due to a bug. Some of these
values 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 confirm that the
offset in resolution observed for the HR grating was not real.  The observed
degradation in the HR resolution until 2015 was real. It was successfully remedied by an
intervention, with the values being 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. </font><p><font size="2">