ITEM_TITLE      Simultaneous arclamp
ITEM_ANAME      simlamp

	      <p>An  exposure (about 120 sec integration time) with the arclamp
	          of the simultaneous calibration unit is daily taken. With the HR grating, they are taken for each of the five fibre systems.
		For the LR grating, only Medusa1 is taken. See the caption for the exact settings used. 
	          These data are used as check of the spectral format (motions of the 2 gratings), of the lamp stability and of the fibre systems health.
	      Find a description of the calibration files and of the grating stability <a href="fmt_qc1.html">here</a>.</p>


TITLE 	QC1 parameters
TABLE_NAME	qc1_parameter
TABLE_TYPE	QC1_TABLE
TABLE_ROW1	[calculated by the QC procedure]	SEP giraffe_simlamp..flux 

TITLE	Trending
	      <p> The<a href="/qc/GIRAFFE/reports/HEALTH/trend_report_SIMLAMP_HC.html" target="_blank"> trending
	            plot</a> has two panels, one with the fluxes from the five HR settings, one with
	            the fluxes from the Medusa1 LR setting (all are taken as daily health checks). </p>

TABLE_NAME	trending1
TABLE_TYPE	FIGURE_1B
TABLE_IMG1	"../img/simcal.gif" width="744" height="249" border="1"
TABLE_CAP1	<b>Plots 1-5</b>: Upper panel, fluxes of the simultaneous calibration arclamp in the five HR settings.

	      <p> Panel 1 shows the lamp flux (in counts per sec) as measured in each
	          slit system with the HR setting (H525.8B).
	          It shows the lamp performance modulated by the fibre efficiencies. The flux difference
	          between the Medusa and the IFU/Argus systems is due to the different fibre diameter
	          (1.2 arcs versus 0.5 arcs).</p>

TABLE_NAME	trending2
TABLE_TYPE	FIGURE_1A
TABLE_IMG1	"../img/simcal2.gif" width="188" height="199" border="1"
TABLE_CAP1	<b>Plot 6</b>: Lower panel, the same for Medusa1 L543.1

	      <p>The second panel shows the fluxes for the Medusa1 LR grating.
	</p>
	      <p>If a certain
	  trend effect is visible in *all* slits, it is likely to be caused by the
	   lamp. If it shows up in one fibre system only, it originates
	  in that particular fibre system. </p>

TITLE	Scoring&thresholds
	Thresholds are set such that over-exposure is avoided. The risk of the lamp getting too bright is that 
 	bright emission lines might affect the science signal of nearby fibres through cross-talk. This is
 	very much depending on setup (central wavelength), and the upper threshold is set conservatively and empirically. The
	lower threshold is set such as to detect lamp failures safely. As the FULL plot shows, lamp fluxes have been
	fairly fluctuating over the years, and also seem to have a seasonal component, all this arguing for a 
	loose and conservative thresholding.

TITLE	History

	      <p>The total lamp flux usually slowly increases with time. It is dimmed electronically
	        when it exceeds a certain threshold, to avoid saturation. This happened  in 2004-02,
	        in 2007-03 and again in 2017-11. In the later case, PPRS-070892 collects the related activities. In 2005-07 ... 2005-09, the lamp faded and needed to be stabilized. 

TITLE	Algorithm
	      <p>One emission line in one of the simultaneous calibration fibres is
	          selected. Its flux is integrated (in counts per sec). This
is done by a QC procedure since there is no pipeline recipe.