QC PLOTS
	LAST	HISTORY
high gain:
median level (master)
read-out noise (raw)
read-out noise (master)
fixed pattern (raw)
structure (raw)
low gain:
median level (master)
read-out noise (raw)
read-out noise (master)
fixed pattern (raw)
structure (raw)
QC1 database (advanced users): browse | plot
Click on CURRENT to see the last trending (Health Check).    Click on HISTORY to see the historical evolution of the trending.

This page refers to the old FORS1 CCD, which was in operation until March 25, 2007. Data from the current CCDs can be found here.

Parameters were measured and trended for all four standard CCD modes: high gain, 1port and 4port readout; low gain, 1port and 4port readout.

QC1 parameters

• median level of master bias (QC1 database table fors1_bias_1CCD, column median_masterA(BCD))
  This is the median level of the master bias for each port.
• median level of first raw bias (QC1 database table fors1_bias_1CCD, column median_rawA(BCD))
  This is the median level of the first raw bias for each port.

The read-out noise is measured in the master (noise_master) and in the raw (RON_r) 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)^-1/2 since typically 4-5 raw files are engaged in the master creation process.

QC1 parameters

• read-out noise of raw bias (QC1 database table fors1_bias_1CCD, column RON_rA(BCD) )
  The difference between the first and second raw bias is computed. The standard deviation of the pixel values in the difference image, divided by √2, is taken as the read-out noise of the raw bias (measured per port).
• read-out noise of master bias (QC1 database table fors1_bias_1CCD, column noise_masterA(BCD) )
  The deviation of pixel values from the median level is determined, excluding deviations by more than 3·(RON_r/√number_of_frames) to avoid deviations not due to the read-out noise. This value is then taken as the read-out noise of the master bias (measured per port).

QC1 parameters

• fixed pattern of raw bias (QC1 database table fors1_bias_1CCD, column FP_rA(BCD))
  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 and read-out noise (scaled by √2). The population standard deviation of this difference is computed and divided by √2. The read-out noise is then quadratically subtracted from the total noise and the result is taken as fixed pattern (measured per port).

QC1 parameters

• structure of first raw bias (QC1 database table fors1_bias_1CCD, column struct_rA(BCD))
  The population standard deviation of the pixel values of the first input raw bias is computed per port. This is the combination of structure, fixed pattern, and read-out noise. The read-out noise and the fixed pattern contributions are then quadratically subtracted.