FORS1 Quality Control: master BIAS

FORS1:
QC1 from master BIAS frames

QC1 PLOTS: BIAS

QC1 ASCII DATA

Year:
Item:	bias
*Chip:**
gain:
bin:

QC1 database (expert mode)

This page refers to the two CCDs installed since March 27, 2007. Data from the previous CCD can be found here.

BIAS

Modes

Parameters are measured and trended for each CCD and the 2 standard CCD modes:
- high gain, 100Kp/s, binning 2x2
- low gain, 200Kp/s, binning 2x2

There are also some measurements for unbinned data (binning 1x1) in the QC1 database.

Parameters

Median level: median master bias level measured in a 1600x400 pixel window. The window is chosen to cover in both CCDs the regions that can be exposed. The short y dimension is explained because of the large Chip 2 vignetting.

Read noise : is measured in the master and in the raw frames; The difference between values in raw files and master files controls the efficiency of the master creation process. The values for master files should be lower than those for raw files by a factor of (4...5)^-1/2since typically 4-5 raw files are engaged in the master creation process.

Fixed pattern : The difference between the first raw bias and the second raw bias (in ADU) shifted by 10x10 pixels, is computed. This is the combination of fixed pattern noise and read out noise (scaled by sqrt(2)). The population standard deviation of this difference is computed and divided by the square root of 2. The read out noise contribution evaluated as QC OUTi RON is then quadratically subtracted from the total noise.

Structure : The population standard deviation of the pixel values of the first input raw bias is computed. This is the combination of structure, fixed pattern noise, and read out noise. The read out noise and the fixed pattern noise contributions are then quadratically subtracted.

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