Quality Control and
Data Processing

HC PLOTS
Geometry calibration parameters
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Astrometry calibration parameters
QC1 database (advanced users): browse | plot

The geometry and astrometric calibrations are taken only few times a year. They are processed by the QC system and qc parameters are trended. It is necessary to always use an astrometric solution together with the geometry table that has been used to compute it. The reason for this is that the astrometric solution may compensate for small inaccuracies in the corresponding geometry table.

The pipeline distribution comes with a carefully verified, matching geometry table and WCS solution as static calibrations.

The instrument geometry or geometrical calibration determines location of each slice of each IFU in the field-of-view. The data are taken roughly every 3 months. Expert knowledge is required to properly process the data, thus the geometry tables are carefully created within the QC system in advance. They are considered as a static calibration which is distributed as part of the MUSE pipeline release package.

QC1_parameters

FITS key	QC1 database: table, name	definition	class*	HC_plot**	more docu
QC.GEO.MASK.ANGLE	muse_geometry..geo_mask_angle	[deg] Angle of the mask with respect to the slicer system, computed as median angle of all slices of all IFUs	HC		[docuSys coming]
QC.GEO.SMOOTH.NX	muse_geometry..geo_smooth_nx	Number of slices that were changed with respect to x position by smoothing	HC		[docuSys coming]
QC.GEO.SMOOTH.NY	muse_geometry..geo_smooth_ny	Number of slices that were changed with respect to y position by smoothing	HC		[docuSys coming]
QC.GEO.SMOOTH.NANGLE	muse_geometry..geo_smooth_nangle	Number of slices that were changed with respect to angle by smoothing	HC		[docuSys coming]
QC.GEO.SMOOTH.NWIDTH	muse_geometry..geo_smooth_nwidth	Number of slices that were changed with respect to width by smoothing	HC		[docuSys coming]
QC.GEO.IFU20.WLEN1.FLUX.MEAN	muse_geometry..geo_ifu20_wlen1_flux_mean	Average integrated flux in all spots at reference wlen1 in IFU20	HC		[docuSys coming]
*Class: KPI - instrument performance; HC - instrument health; CAL - calibration quality; ENG - engineering parameter **There might be more than one.

Trending

We trend selected QC parameters retrieved from the PRO.CATG=GEOMETRY_TABLE master products.

Scoring&thresholds Geometry calibration

The parameters are not scored.

History

Date	event
2017-10-01	pipeline improved; QC took over creating new versions of GEOMETRY_TABLE whenever necessary

Algorithm Geometry calibration

The data - full exposure sequence of raw multi-pinhole mask images (more than 50 frames allowed), is averaged. The averaged image together with the trace table and wavelength calibration as well as the line catalog are used to detect spots. The detection windows are used to measure the spots on all images of the sequence, the result is saved, with information on the measured PSF, in the spots tables. Then properties of all slices are computed, first separately on each IFU to determine the peak position of the mask for each slice and its angle, subsequently the width and horizontal position. Then, the result of all IFUs is analyzed together to produce a refined horizontal position, applying global shifts to each IFU as needed. The vertical position is then determined using the known slice ordering on the sky; the relative peak positions are put into sequence, taking into account the vertical offsets of the pinholes in the mask. If the --smooth parameter is set to a positive value, it is used to do a sigma-clipped smoothing within each slicer stack, for a more regular appearance of the output table. The table is then saved.

The main product of the astrometric calibration is the ASTROMETRY_WCS file which is a bare FITS header containing the world coordinate solution. The secondary product is DATACUBE_ASTROMETRY, it is not needed for further processing. The astrometric data should be always processed with corresponding (taken very close in time) geometry calibration. Because of this special requirement, the ASTROMETRY_WCS is provided as a static calibration and distributed with the pipeline installation.

QC1_parameters

FITS key	QC1 database: table, name	definition	class*	HC_plot**	more docu
QC.ASTRO.SCALE.X	muse_astrometry..scale_x	[arcsec] Computed scale in x-direction	HC		[docuSys coming]
QC.ASTRO.SCALE.Y	muse_astrometry..scale_y	[arcsec] Computed scale in y-direction	HC		[docuSys coming]
QC.ASTRO.ANGLE.X	muse_astrometry..angle_x	[deg] Computed angle in x-direction	HC		[docuSys coming]
QC.ASTRO.ANGLE.Y	muse_astrometry..angle_y	[deg] Computed angle in y-direction	HC		[docuSys coming]
QC.ASTRO.MEDRES.X	muse_astrometry..medres_x	[arcsec] Median residuals of astrometric fit in x-direction	HC		[docuSys coming]
QC.ASTRO.MEDRES.Y	muse_astrometry..medres_y	[arcsec] Median residuals of astrometric fit in y-direction	HC		[docuSys coming]
*Class: KPI - instrument performance; HC - instrument health; CAL - calibration quality; ENG - engineering parameter **There might be more than one.

Trending

We trend selected QC parameters retrieved from the PRO.CATG=PIXTABLE_ASTROMETRY master products.

Scoring&thresholds Astrometric calibration

The parameters are not scored.

History

Date	event
2017-10-01	pipeline improved; QC took over creating new versions of static ASTROMETR_WCS calibration whenever necessary

Algorithm Astrometric calibration

Pixel tables from all IFUs are merged, correction for differential atmospheric refraction is applied, and data are resampled from all exposures into a datacube. The cube is used to detect objects which are then matched to their reference positions from which a two-dimensional WCS solution is computed.