Quality Control and
Data Processing

HC PLOTS
Sensitivity
Conversion factor
Background
Image quality
QC1 database (advanced users): browse | plot

VISIR imaging standard stars are observed during night in order to monitor changes of the MIR observing conditions and to provide photometric flux calibration. The calibration plan requires the imaging standard stars to be taken within +/- 3 hours from the science imaging frames.

Imaging Standard Star frame. An example observation of an imaging standard star with the post-upgrade detector. The integrated frame of all half-cycle frames at the first nodding position is shown. Note that the actual field of view is smaller than the detector size.

Imaging Standard Star frame (pre-upgrade). This is an example pipeline product from an imaging standard star observation. Note persistent horizontal stripes characteristic for the pre-upgrade detector.

QC1_parameters

FITS key	QC1 database: table, name	definition	class*	HC_plot**	more docu
QC.SENSIT	visir_zp_img..sensit	sensitivity (mJy/10sigma/1hr)	HC		[docuSys coming]
*Class: KPI - instrument performance; HC - instrument health; CAL - calibration quality; ENG - engineering parameter **There might be more than one.

Trending

Sensitivity is trended for a number of N band and Q band filters.

Scoring&thresholds Sensitivity

Scoring is not implemented.

History

Date	event
until May 2012	pre-upgrade sensitivities were trended for both small-field (SF) and intermediate-field (IF) pixel field of view
since April 2015	start of operations after upgrade; new detectors, only SF pixel field of view is offered

Algorithm Sensitivity

Sensitivity is the estimated limiting flux expected in an 1 hour on-source integration of a point source detected with S/N of 10. Units: mJy at 10 sigma in 1hr.

QC1_parameters

FITS key	QC1 database: table, name	definition	class*	HC_plot**	more docu
QC.CONVER	visir_zp_img..conver	conversion factor (ADU/Jy)	HC		[docuSys coming]
*Class: KPI - instrument performance; HC - instrument health; CAL - calibration quality; ENG - engineering parameter **There might be more than one.

Trending

The conversion factor is trended for a number of N band and Q band filters.

Scoring&thresholds Conversion factor

Scoring is not implemented.

History

Date	event
until May 2012	pre-upgrade conversion factor trended for both small-field (SF) and intermediate-field (IF) pixel field of view
since April 2015	start of operations after upgrade; new detectors, only SF pixel field of view is offered

Algorithm Conversion factor

Conversion between ADU and Jy: F(total oberved) / F(model) [ADU/Jy], where F(total observed) is the measured and F(model) is the predicted flux for the standard star from a catalog.

QC1_parameters

FITS key	QC1 database: table, name	definition	class*	HC_plot**	more docu
BACKGD.MEAN	visir_zp_img..backgd_mean	estimated mean of the background	HC		[docuSys coming]
*Class: KPI - instrument performance; HC - instrument health; CAL - calibration quality; ENG - engineering parameter **There might be more than one.

Trending

Background is trended for a number of N band and Q band filters.

Scoring&thresholds Background

Scoring is not implemented.

History

Date	event
until May 2012	pre-upgrade background level were trended for both small-field (SF) and intermediate-field (IF) pixel field of view
April 2015	start of operations after upgrade; background level not determined and trended
August 2015	trending of background level resumed

Algorithm Background

The mean background level is measured from the half-cycle frames (in ADU).

QC1_parameters

FITS key	QC1 database: table, name	definition	class*	HC_plot**	more docu
QC.FWHMX	visir_zp_img..fwhmx	FWHM in x	HC		[docuSys coming]
QC.FWHMY	visir_zp_img..fwhmy	FWHM in y	HC		[docuSys coming]
QC.GAUSSFIT.FWHM_MAX	visir_zp_img..gauss_fwhm_max	max FWHM from Gauss fit to source	HC		[docuSys coming]
QC.GAUSSFIT.FWHM_MIN	visir_zp_img..gauss_fwhm_min	min FWHM from Gauss fit to source	HC		[docuSys coming]
*Class: KPI - instrument performance; HC - instrument health; CAL - calibration quality; ENG - engineering parameter **There might be more than one.

Trending

Image quality is trended for N and Q band filters.

Scoring&thresholds Image quality

Scoring is not implemented.

History

Date	event
April 2015	start of operations after upgrade; trending of fwhmx and fwhmy introduced
February 2016	Gaussian fit is introduced

Algorithm Image quality

fwhmx, fwhmy: FWHM of the fitted profile in X and Y direction, measured in pixels and converted to arc seconds for trending
gauss_ fwhm_min, gauss_fwhm_max: FWHM (minimum and maximum) from a 2D Gaussian fit to the star image, more reliable than the FWHM in X or Y direction