[ ESO ]
VISIR Quality Control:
DARK frames

CAL | HC | refs | QC
QUALITY CONTROL
    HOME
VISIR QC
Trending & QC1
   dark
Pipeline
Data Management
QC links:
read noise | dark level | det. temperature
 
QC PLOTS
  CURRENT HISTORY
read-out noise
dark level
temperature
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.


One set of DARK frames for the imaging and one for the spectroscopic detector is taken every day during daytime. Each set consists of 3 raw frames and is always obtained with the same instrument setup: detector integration time DET.DIT=0.02s and number of detector sub-integrations DET.NDIT=1000. DARK frames are not used for calibrating science data but are utilized to monitor performance of the VISIR detectors.

DARK frame of the imaging detector (pre-upgrade). This is a master DARK frame which was build by averaging 3 raw frames. Note bright horizontal stripes which are characteristic of the pre-upgrade imaging detector. Also visible are clusters of bad pixels. DARK frame of the spectroscopic detector (pre-upgrade). This is a master DARK frame which was build by averaging 3 raw frames. Here, characteristic stripes are vertical.

top read-noise

QC1 parameters
parameter QC1 database: table, name procedure
ron1 visir_dark_img, ron1
visir_dark_spc, ron1
Read-out noise calculated from the difference image of the 2nd - 1st raw frame. It is the median of the standard deviations measured from 100 4x4 windows on the difference frame, multiplied by sqrt(NDIT/2).
ron2 visir_dark_img, ron2
visir_dark_spc, ron2
Same as ron1 but from the difference of the 3rd - 2nd frame.

Trending

The first dark frame of a stack is sometimes contaminated by transient features that artigicially increase the background level and therefore the RON calculation. These features are usually not present in the second and third frames. Therefore, the ron2 parameter is more stable and is used for trending.

History

April 2015: start of operations after upgrade with new detectors

top dark level

QC1 parameters

parameter QC1 database: table, name procedure
darkmed visir_dark_img, darkmed
visir_dark_spc, darkmed
The median dark level is calculated in the central part of the master dark.

Trending

The median dark is trended separately for both the imaging and the spectroscopic detector.

History

April 2015: start of operations after upgrade with new detectors

top detector temperature

QC1 parameters
parameter QC1 database: table, name procedure
darkmed visir_dark_img, ins_sens30_val
visir_dark_spc, ins_sens31_val
Values as recorded in the header keys INS.TEMP30.VAL and INS.TEMP31.VAL.

Trending

The detector temperature is trended separately for both the imaging and the spectroscopic detector.

History

2010-05-12: the temperature of the imaging detector is read from keyword INS.TEMP30.VAL and of the spectroscopic detector from keyword INS.TEMP31.VAL. Before that date different keywords were used: INS.SENS30.VAL and INS.SENS31.VAL, respectively. The names of the QC1 database columns remained unchanged.



 
[ESO][Index][Search][Help][News]