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ESPRESSO: Bias
Bias level | Read-out noise (RON)

 
HC PLOTS
Bias level
Bias RON
QC1 database (advanced users): browse | plot

Bias frames are measured during daytime. They are measured daily with 1x1 binning (fast read-out, for HR and UHR observations) and with 2x1 binning (slow read-out, for HR observations). Bias frames with 4x2 and 8x4 binning (slow read-out) are typically only taken when MR science data have been observed during the night.

A complete set per binning consists of 10 bias frames.

Bias frame. Example frame for the blue detector. Note the different bias level for the 16 read-out ports


Bias level
Bias level | Read-out noise (RON)

The master bias is the median stack of the (typically) ten input raw bias frames.

QC1_parameters

FITS key QC1 database: table, name definition class* HC_plot** more docu
none espresso_bias..bias_mean_avg average bias level across read-out portsCAL [docuSys coming]
none espresso_bias..bias_mean_rms RMS of bias level across read-out ports CAL [docuSys coming]
*Class: KPI - instrument performance; HC - instrument health; CAL - calibration quality; ENG - engineering parameter
**There might be more than one.

ESPRESSO has two chips, one for the BLUE and one for the RED arm. Each chip has 16 read-out ports. Bias QC parameters are determined by the pipeline per read-out port which leads to 16 different values for each QC parameter per chip. They are written as header keys in the form of (for the mean bias):

QC.EXT<n>.ROX<x>.ROY<y>.BIAS.MEAN

with <n> being the detector (0 for BLUE and 1 for RED), <x> the x position of the read-out on the chip (0, 1, to 7), and <Y> the y position (0 or 1). The corresponding names in the QC1 database follow the scheme

bias_mean_<x>_<y> .

In addition to these individual values, the average and the RMS per chip are calculated and written into the QC1 database.

Trending

The bias QC1 parameters are trended separately for the four different read-out modes: 1x1 binning (fast read-out), and 2x1, 4x2, and 8x4 binning (all slow read-out).

Scoring&thresholds Bias level

The average and RMS QC parameters are scored per detector. Thresholds have been set according to the measured fluctuation in October and November 2018.

History

Bias level changed a few times during commisioning.

Algorithm Bias level

The bias level is determined by the pipeline recipe per read-out port. The QC procedures calculate in addition the average and the RMS of all 16 ports per detector.


Read-out noise (RON)
Bias level | Read-out noise (RON)

QC1_parameters

FITS key QC1 database: table, name definition class* HC_plot** more docu
none espresso_bias..bias_ron_avg average RON across read-out ports HC [docuSys coming]
none espresso_bias..bias_ron_rms RMS of RON across read-out ports HC [docuSys coming]
*Class: KPI - instrument performance; HC - instrument health; CAL - calibration quality; ENG - engineering parameter
**There might be more than one.

ESPRESSO has two chips, one for the BLUE and one for the RED arm. Each chip has 16 read-out ports. Bias QC parameters are determined by the pipeline per read-out port which leads to 16 different values for each QC parameter per chip. They are written as header keys in the form of (for the RON):

QC.EXT<n>.ROX<x>.ROY<y>.BIAS.RON

with <n> being the detector (0 for BLUE and 1 for RED), <x> the x position of the read-out on the chip (0, 1, to 7), and <Y> the y position (0 or 1). The corresponding names in the QC1 database follow the schema

bias_ron_<x>_<y> .

In addition to these individual values, the average and the RMS of these values are calculated per chip and written into the QC1 database.

Trending

The bias QC1 parameters are trended separately for the four different read-out modes: 1x1 binning (fast read-out), and 2x1, 4x2, and 8x4 binning (all slow read-out).

Scoring&thresholds Read-out noise (RON)

The average and RMS QC parameters are scored per detector. Thresholds have been set according to the measured fluctuation in October and November 2018. They are set close to the nominal values of 8 e-/pix (blue CCD) and 5 e-/pix (red CCD) for fast read-out, and 3 e-/pix and 2 e-/pix for slow read-out. The blue CCD shows a higher than nominal RON in slow read-out for the MULTIMR modes.

History

There was a period with increased electronic noise during commisioning.

Algorithm Read-out noise (RON)

RON is determined by the pipeline recipe per read-out port. The QC procedures calculate in addition the average and the RMS of all 16 ports per detector.


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