This plot shows the relation between SNR (called 'qc_s2n' in the database) and average counts (mean_reduced) for the UVES
IDPs, older releases UVESR_2 and UVES_R3. They are superseded now by UVES_STACK, still this coparison is relevant. 

It  covers the time range between start of operations (2000-03) and 2007-03-31. </font><p><font size="2">

We have selected reference settings 346 and 437 for the BLUE arm, and 580 and 860 for the RED arm. The blue or red data points belong to the old release. The cyan and yellow data points belong to the improved data release which supersedes the old release. Note that apart from the strong and obvious improvements in plots #2 and #3 (due to the bug in the pipeline) there is also a more subtle, general improvement for SNR.</font><p><font size="2">

The broken lines indicate 
scaled square-root laws that are
purely empirical. They are plotted for orientation and are not fits.