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Quality Control and
Data Processing

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Trending & QC1
   ZIMPOL dark
QC links:
SPHERE: ZIMPOL dark frames
dark level IMG readout mode [ADU/h]
QC1 database (advanced users): browse | plot
dark level POL slow read mode CAM1 [ADU/h]
dark level POL slow read mode CAM2 [ADU/h]
dark level POL fast read mode CAM1 [ADU/h]
dark level POL fast read mode CAM1 [ADU/h]
QC1 database (advanced users): browse | plot

Optical dark frames are acquired once a month in all three read modes to monitor the dark radiation. The exposure time is 100 sec, the QC paramaters in the plot are scaled to ADU/h.

ZIMPL Dark Level


FITS key QC1 database: table, name definition class* HC_plot** more docu
QC.DOUBLE.IMAGE.IFRAME.MEDIAN sphere_zimpol_dark_img..qc_median_iframe HC [docuSys coming]
QC.DOUBLE.IMAGE.LEAKAGE.MEDIAN sphere_zimpol_dark_img..qc_median_pframe median counts polarimetric HC [docuSys coming]
QC.DOUBLE.IMAGE.IFRAME.RMS sphere_zimpol_dark_img..qc_rms_iframe rms of counts imageHC [docuSys coming]
QC.DOUBLE.IMAGE.LEAKAGE.RMS sphere_zimpol_dark_img..qc_rms_pframe rms of counts polarimetric HC [docuSys coming]
QC.QUAD.IMAGE.ZERO.ODD.MEDIAN sphere_zimpol_dark_pol..qc_med_zero_odd polphase zero, odd cycle HC [docuSys coming]
QC.QUAD.IMAGE.ZERO.EVEN.MEDIAN sphere_zimpol_dark_pol..qc_med_zero_even polphase zero, even cycleHC [docuSys coming]
QC.QUAD.IMAGE.PI.ODD.MEDIAN sphere_zimpol_dark_pol..qc_med_pi_odd polphase pi, odd cycleHC [docuSys coming]
QC.QUAD.IMAGE.PI.EVEN.MEDIAN sphere_zimpol_dark_pol..qc_med_pi_even polphase pi, even cycle HC [docuSys coming]
QC.QUAD.IMAGE.ZERO.ODD.RMS sphere_zimpol_dark_pol..qc_rms_zero_odd polphase zero, odd cycle HC [docuSys coming]
QC.QUAD.IMAGE.ZERO.EVEN.RMS sphere_zimpol_dark_pol..qc_rms_zero_even polphase zero, even cycleHC [docuSys coming]
QC.QUAD.IMAGE.PI.ODD.RMS sphere_zimpol_dark_pol..qc_rms_pi_odd polphase pi, odd cycleHC [docuSys coming]
QC.QUAD.IMAGE.PI.EVEN.RMS sphere_zimpol_dark_pol..qc_rms_pi_even polphase pi, even cycle HC [docuSys coming]
*Class: KPI - instrument performance; HC - instrument health; CAL - calibration quality; ENG - engineering parameter
**There might be more than one.


The plot shows the optical CCD dark current values and RMS as derived from the zimpol dark recipe for read mode StandardImaging. The recipe expresses dark values in units of the used EXPTIME (here per 100 sec), the values in the plot are scaled to ADU/hour.

The plot shows QC parameters derived from the ZIMPOL dark recipe for both read modes SlowPolarimetry and FastPolarimetry.

odd/even means the cycle
zero/pi means the polarimetric phase

The recipe arranges the phase=pi rows and the phase=zero rows of the raw frame and writes them in different extensions of the pipeline product. The QC parameters describe the median and the rms of these imaging products. The QC parameter 'median' retrieved and stored is given in ADU per 100 sec, the values in the plots are scaled to ADU/hour.

Scoring&thresholds ZIMPL Dark Level

The median dark levels are scored.


  • From 2015-04-01 to 2015-11-01: The ZIMPOL CCDs accumulate counts when not being read out since a longer time (several hours). The first ZIMPOL calibration in the day-time calibration batch is the imaging dark, of which the first of two frames is contaminated, while the second one is clean and corresponds to a proper measurement of the dark current. In case the calibration is acquired in cube mode, only the first layer of the data cube is affected, while all further subintegrations are not affected. The clean dark current corresponds to a value of ~3 ADU/100sec, the contaminated and useless value is about ~10 ADU/100sec. The issue is solved since 2015-12-01.
  • As occured on 2016-09-23, the saturated modemeff calibration acquired directly in advance of the ZIMPOL imaging mode dark calibration left a double as large dark current on the detector, a kind of persistence.

Algorithm ZIMPL Dark Level

The monitored values are directly derived from the intermediate pipeline product frames.

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