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NACO Quality Control:
DARK frames

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read-noise | dark level | hot/cold pixels
 
QC PLOTS
  CURRENT HISTORY
read-noise and dark level HC setups
hot/cold pixels
QC1 database (advanced users): browse | plot
   Click on CURRENT to see the current trending (Health Check).
   Click on HISTORY to see the historical evolution of the trending.


A number of DARK frames is taken within the NACO daytime calibrations in case NACO science observations have been acquired in the night. Each DARK consists of 3 raw frames obtained with the instrumental setting matching the one used for science observations. The parameters matched are:

  • DET.DIT - detector integration time
  • DET.NDIT - number of sub-integrations
  • INS.OPTI7.NAME - camera (e.g. S17, L54)
  • DET.NCORRS.NAME - detector read-out mode
  • DET.MODE.NAME - detector mode
In addition, each day, 3 dark frames are taken for the health check purpose, always with the same setup:
  • DET.DIT=1.7927 s, (since 2015: 1.7892s) DET.NDIT=1, INS.OPTI7.NAME=S27, DET.NCORRS.NAME=FowlerNsamp, DET.MODE.NAME=HighSensitivity
  • DET.DIT=0.5 s, DET.NDIT=100, INS.OPTI7.NAME=S27, DET.NCORRS.NAME=Double_RdRstRd, DET.MODE.NAME=HighSensitivity
  • DET.DIT=300 s, DET.NDIT=1, INS.OPTI7.NAME=S27, DET.NCORRS.NAME=FowlerNsamp, DET.MODE.NAME=HighSensitivity

They are utilized to monitor performance of the NACO detector.

 

The following images are from 2016-11-28.

DARK frame - 0.5s, Double_RdRstRd, HighSensitivity This is an example of the master calibration DARK frame - NC_DCAL_0_5_S27_F_DRHS.fits. It is a pipeline product of the "naco_img_dark" recipe. The horizontal stripes on the edges of the detector are features characteristic to the Double_RdRstRd read-out mode. Note the dead columns (every 8th is affected) in the lower left quadrant. The bright dot at the upper edge and the upper right corner are known bad pixel areas.
1.7_FS DARK frame - 1.7s, FowlerNsamp, HighSensitivity This is an example of the master calibration DARK frame - NC_DCAL_1_7..._S27_F_FSHS.fits. It is a pipeline product of the "naco_img_dark" recipe. The bright, diagonal stripes are associated with the "light leakage". They become prominent structures when darks are taken with long DITs.
300FS DARK frame - 300s, FowlerNsamp, HighSensitivity This is an example of the master calibration DARK frame - NC_DCAL_300_S27_F_FSHS.fits. It is a pipeline product of the "naco_img_dark" recipe. The bright, diagonal stripes are associated with the "light leakage". They become prominent structures when darks are taken with long DITs. The bright stripes are variable: the pattern occurs at a slightly different position each time the camera is moved.
UHWD DARK frame - 0.18s, Uncorr, HighWellDepth This is an example of the master calibration DARK frame - NC_DCAL_0_18_L27_F_UCHW.fits. It is a pipeline product of the "naco_img_dark" recipe. The dark level is at -1800 ADU


In addition to the QC parameters calculated by the NACO dark pipeline recipe, several QC parameters are calculated by QC procedures. They all are stored in the NACO QC1 parameter database.

The NACO detector can be operated in normal (DET.FRAM.TYPE=INT) and in cube mode (DET.FRAM.TYPE=CUBE2). In cube mode, the detector adds two more rows at the upper rim, that the read-out size is 1024x1026 pixel instead of the 1024x1024 pixel in normal read mode. Furthermore the detector can be operated in any used-defined window read out mode. The QC monitoring covers:

  • normal mode (DET.FRAM.TYPE=INT), full readout (NAXIS1 x NAXIS2 = 10124 x 1024)
  • the first layer of a cube (DET.FRAM.TYPE=CUBE2), full readout (NAXIS1 x NAXIS2 = 1024 x 1026)
  • darks for M-band pre-defined 512 x 512 pixel window readout and 512 x 514 pixel window (cube mode)

Other Window options other than 512 x 512 and 512 x 514 ore not pipeline supported and are not subject of QC checks.

The operationally most critical detector characteristics derived from dark calibration frames are monitored by the following four QC parameters:

top read-noise

QC1 parameters

parameter QC1 database: table, name procedure
"dark_ron12": read-out noise naco_dark, dark_ron12 read-out noise calculated from the 2nd-1st raw; it is a median of the standard deviations measured from 100 4x4 windows on the difference frame, multiplied by sqrt(NDIT/2)

The upper three boxes of the following plot show the temporal evolution of the read-out noise for three daily taken detector setups.

top dark level

QC1 parameters

parameter QC1 database: table, name procedure
"dark_median": median dark level (ADU/pixel/s) naco_dark, dark_median median dark level in the central part of the master dark

The upper three boxes of the following plot show the temporal evolution of the dark level for three daily taken detector setups.

top 8-column noise

The 8-column noise is a special feature of the NACO detector, which became dominant in Feb 2012, when the upper right 512x512 pixel detector quadrant showed an extra signal as repetitive pattern in every eightst column.

QC1 parameters

parameter QC1 database: table, name procedure
8-pixel noise naco_dark, noise_UL_lf_fpn The rms over the median-collapsed row of a 512x512 pixel detector quadrant.

This QC parameter deserved temporarily its own HC plot in 2012. The HC was decommissioned in 2013. The QC parameter noise_UL_lf_fpn (low frequency fixed pattern noise in the UpperLeft quadrant) as well as its complements for the other three detector quadrants are continuously acquired and are available in the QC1 DB.

top hot/cold pixels

QC1 parameters

parameter QC1 database: table, name procedure
"num_cold": number of cold pixels naco_dark, num_cold calculated by the pipeline recipe naco_img_dark
"num_hot": number of hot pixels naco_dark, num_hot calculated by the pipeline recipe naco_img_dark

The trending plot shows the number of the hot and cold pixels measured in the dark frames. The data points are separated by the detector read-out mode.

 


 
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