GIRAFFE trending system: HISTORY plot
Last update: 2007-02-14T09:30:29 (UT)
same group: dark linearity&gain fp-noise contamination   correlations
close window history: 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024   HEALTH
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*Date on this monitor changes at 21:00 UT
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Plot Symbol
[info]		 Source* Average [info] Thresholds [info] N_data Data downloads Remarks
method value unit method value
1 •QC1DB MEAN0.428 % 3SIG± 0.011 19 this | last_yr | all fixed-pattern noise, normalized to mean flux (220 sec exposures)
note: downloaded data: any exposure time!
2 •QC1DB none  ADU none   150 this | last_yr | all measured fixed-pattern noise, with linear fit
2 •QC1DB none  ADU none   150 this | last_yr | all measured photon noise, with square-root fit
*Data sources: OPSLOG: Paranal ops logs; QC1DB: QC1 database; LOCAL: local text file
This plot

This is the trending plot for the monitoring of the GIRAFFE detector noise parameters, derived from image flats.

Data for the old CCD (used until 2008-03) are complete. Due to issues with the pipeline recipe for detector monitoring, data for the new CCD have been calculated only since 2009-10.

These frames are taken approximately once per month, as a sequence with exposure time increasing from 0.5 sec to 220 sec. For each value, a set of 2 image flats is taken, just exposing the CCD without the fibre system.

For each pair, the difference frame is calculated from which the photon noise is determined. Then a raw frame is taken, shifted by one pixel in X and Y, and subtracted, in order to randomize the fixed-pattern noise. Finally the measured total noise and the photon noise are subtracted and give the fixed-pattern noise. It is trended as fraction of the mean signal in plot no. 1.

The second plot displays the whole sequence of image flats, with the measured photon noise on a square-root curve, and the fixed-pattern noise on a linear curve. The intersection of both fits marks the transition from the photon-noise to the fixed-pattern noise regime.

Find more information about GIRAFFE image flats frames here.

Other QC parameters related to detector properties (like dark, linearity, gain) are trended in the same group.  

General information

Click on any of the plots to see a close-up version. The latest date is indicated on top of the plot, data points belonging to that date are specially marked.

If configured,

  • statistical averages are indicated by a solid line, and thresholds by broken lines
  • outliers are marked by a red asterisk. They are defined as data points outside the threshold lines
  • "aliens" (= data points outside the plot Y limits) are marked by a red arrow (↑ or ↓)
  • you can download the data for each parameter set if the 'Data downloads' link shows up