Quality Control and
Data Processing

HC PLOTS
reset level
reset rms
differential rms
QC1 database (advanced users): browse | plot

The Daily Health Check templates for technical calibrations acquire each day reset frames of the following (only) setup:

• NCORRS=Uncorr, NDIT=1, DIT=1.001100 sec

where 1.001100 is the MINDIT, the minimum possible DIT that can be achieved with the currently configured read speed. RESET calibrations are technical calibrations, they are not used to calibrate other calibrations or science date. A raw DARK frame (the read mode is double correlated) is a result of a reset-read-read sequence, where the first read result is internally subtracted from the second read result and the reset level cancels out. A raw RESET frame (the read mode is uncorrelated) is a result of a reset-read sequence which shows the reset level. No other calibrations use DET.NCORRS=Uncorr, only the technical RESET calibrations.

QC1_parameters

FITS key	QC1 database: table, name	definition	class*	HC_plot**	more docu
QC.RESETMED	vircam_reset..qc_reset_med		HC		[docuSys coming]
QC.RESETRMS	vircam_reset..qc_reset_rms		HC		[docuSys coming]
QC.RESETDIFFRMS	vircam_reset..qc_resetdiff_rms	rms of reset difference frame	ENG		[docuSys coming]
*Class: KPI - instrument performance; HC - instrument health; CAL - calibration quality; ENG - engineering parameter **There might be more than one.

• The QC.RESETMED is the median of the master reset frame (= average of 5 raw bias frames).
• The QC.RESETRMS is the RMS over all pixel of the master bias product.
• A reference reset frame is maintained and updated after detector interventions. The QC.RESETDIFFRMS parameter is the median of the reset difference frame (master minus reference). The QC.RESETDIFFRMS is the robust RMS estimate of the bias difference frame.

Trending

As for all QC parameters that come per chip, the upper left box of the HC plot shows the average over 16 detector-specific values, the lower left box shows the rms over 16 detectors, the upper right plot shows 16 individual detector values, and the lower right plots shows the detector specific scores.

Scoring&thresholds RESET frames

The reset level and the reset rms is trended and scored in the upper left box of the plot. The rms of the difference product as a highly sensitive parameter for the structural noise in Uncorr read mode is monitored as well. Relaxed scores are used.

History

When the instrument is warmed up and cooled down as part of a scheduled maintenance or an unexpected longer power cut on the site, the detectors show the following pattern: The reset level values and the reset rms values are higher than before the warm-up and decrease slowly in an asymptotic manner to the pre-intervention value. This might take weeks or longer. The strongest effect is seen in detectors #3, #13, and #14. From the long-term trend, the following warm-up events can be identified:

Date	event
2012-12-10	closed cycle cooler intervention, see PPRS 48376
2013-08-06
2014-07-15
2015-03-25
2015-06-15
2015-11-25
2017-03-08	closed cycle cooler intervention
2017-05-03	detector controller electronics power-cycled to reduce number of string horizontal stripes events in dark frames
2018-06-20	closed cycle cooler intervention
2018-06-26	The REFERENCE_RESET product has been updated. The new one is from 2018-06-26. The QC parameter shows now the deviations from the 2018-06-26 instance of the RESET product.

Algorithm RESET frames

The median and the robust RMS (via MAD) of the PRO.CATG=MASTER_BIAS and the PRO.CATG=DIFFIMG_BIAS products are taken