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GIRAFFE trending system: HISTORY report
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Last update: 2019-02-26T16:08:32 (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 FULL
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*Date on this monitor changes at 21:00 UT
png: Information and research:
- png file - advanced studies: QC1 browser | QC1 plotter
- more detailed correlations about linearity and gain here
Plot
?
Symb
?
Source
*
Average ? Thresholds ? N_
data
QC1
parameter
Data
downloads
Remarks
method value unit method value
1 QC1DB none     VAL-0.025,0.005 15 qc_lin_eff this | last_yr | all new CCD (after 2008-04): effective non-linearity correction (from DETMON recipe) (normal read mode)
2 QC1DB MEAN 2.32 el/ADU VAL2.1,2.5 73 conad this | last_yr | all new CCD (after 2008-04): GAIN*, from image flats with exptime < 10 sec (normal read mode)
2 oQC1DB none   el/ADU none  0 conad this | last_yr | all old CCD (before 2008-04): GAIN*, from image flats with exptime > 60 sec
(*note: the QC1 parameter is called conad by mistake, it should read gain)
*Data sources: QC1DB: QC1 database; LOCAL: local data source
Plot 1
data source:giraffe_ccd
(QC1 database)
dataset:qc_lin_eff
average:none
fixed thresholds:-0.025...0.005 
N_data plotted:15
[click plot for closeup]
Plot 2
data source:giraffe_ccd
(QC1 database)
dataset:
(numbers below apply to this dataset)
conad
mean:2.32el/ADU
fixed thresholds:2.1...2.5el/ADU
N_data plotted:73
[click plot for closeup]
This plot

This is the trending plot for the monitoring of the GIRAFFE CCD linearity and gain. These parameters are derived from image flats. These data are taken about monthly. Since 2008-07, they are acquired with the common detector monitoring template and reduced with the corresponding common recipe.

The CCD was upgraded between 2008-03 and 2008-05. Data from the new CCD are marked "NEW".

A sequence of image flats is exposed between 0.5 and 220 secs. A third-order polynomial is fitted to the mean exposure level as a function of exposure time. An effective non-linearity correction is derived from this and plotted in box 1. This is available only since 2008.

The gain (in electrons per ADU) is also monitored here, as box 2. It is measured from the difference between two identical raw frames, by comparing the square root of the signal to its measured rms. Plotted here is the asymptotic value for exptime → 0 which is the true gain. Find the complete correlation as plot no. 4 under 'correlations'. The value stored in the file headers is very close to the one plotted here.  


General information

Click on any of the plots to see a close-up version.

The latest date is indicated on top of the plot.

If configured,

  • data points belonging to the latest date are specially marked
  • 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