Quality Control and
Data Processing

HC PLOTS
resolving power
dispersion
QC1 database (advanced users): browse | plot

IFS wavelength calibration spectra raw frames are acquired in IFU mode and show arc line spectra. Spectra come in two different setups: prism_YJ and prism_YJH. There are four monochromatic laser lamps, each once produces one arc line in the spectrum at the following nominal wavelengths:

0.9877 mu, 1.1237 mu, 1.3094 mu and 1.5451 mu,

The latter one is only covered by the wider wavelength range of the prism_YJH. The pipeline recipe generates a product with PRO.CATG=IFS_WAVECALIB to be used to calibrate science spectra and a product with PRO.CATG=IFS_WAVECALIB_CUBE, an IFU fits cube which is analyzed by QC scripts in the following.

Median arc spectrum of the IFS wavelength cube product for prism_YJ with three arc lines. Each arc line is fit by a Gaussian to monitor resolving power, arc line flux and measured wavelength.

Median arc spectrum of the IFS wavelength cube product for prism_YJH with four arc lines. Each arc line is fit by a Gaussian to monitor resolving power, arc line flux and measured wavelength.

QC1_parameters

FITS key	QC1 database: table, name	definition	class*	HC_plot**	more docu
[QC script]	sphere_ifs_wave..respow1	laser lamp1 arc line respow	HC		[docuSys coming]
[QC script]	sphere_ifs_wave..respow2	laser lamp2 arc line respow	HC		[docuSys coming]
[QC script]	sphere_ifs_wave..respow3	laser lamp3 arc line respow	HC		[docuSys coming]
[QC script]	sphere_ifs_wave..respow4	laser lamp4 arc line respow	HC		[docuSys coming]
*Class: KPI - instrument performance; HC - instrument health; CAL - calibration quality; ENG - engineering parameter **There might be more than one.

The QC script analyses the median extracted spectrum out of the pipeline cube product. Each arc line is fit by a Gaussian and the best fit sigma is scaled to a FWHM an divided by the central arc line wavelength. By this, from each arc line a value of the resolving power is retrieved.

Trending

The resolving power of the up to four arc lines is monitored

The resolving power of the individual arc line show a strong but small dependence of the IFS optical temperature, which monitored in a < a href="/qc/SPHERE/reports/HEALTH/trend_report_IFS_REPO_TEMP_HC.html"> separate plot.

Scoring&thresholds IFS resolving power

All QC parameters are not scored.

History

• 2021-06-11: new pipeline version from 2021-03-16 on. The pipeline based resolving power is now given in units of FWHM (before in units of Gaussian Sigma)
• 2019-05-27: The pipeline (version 0.37) reports only the mean initial guess resolving power, which is not senistive to any real resolving power variations. The QC script analyses the cube product and provides the best fit values in the QC1 DB.
• 2017-11-29: The spos pipeline products are based on V0.28 (before V0.18). The initial guess of the dispersion and the resolving power has changed.

Algorithm IFS resolving power

The QC script fits a Gaussian to each of the monochromatic laser lamp arc lines.

QC1_parameters

FITS key	QC1 database: table, name	definition	class*	HC_plot**	more docu
[QC script]	sphere_ifs_wave..flux1	laser lamp1 arc line flux	HC		[docuSys coming]
[QC script]	sphere_ifs_wave..flux2	laser lamp2 arc line flux	HC		[docuSys coming]
[QC script]	sphere_ifs_wave..flux3	laser lamp3 arc line flux	HC		[docuSys coming]
[QC script]	sphere_ifs_wave..flux4	laser lamp4 arc line flux	HC		[docuSys coming]
*Class: KPI - instrument performance; HC - instrument health; CAL - calibration quality; ENG - engineering parameter **There might be more than one.

The QC script analyses the median extracted spectrum out of the pipeline cube product. Each arc line is fit by a Gaussian and the best fit sigma is scaled to a FWHM an divided by the central arc line wavelength. By this, from each arc line a value of the resolving power is retrieved.

Trending

Each arc line is generated by a separate laser lamp. The integrated flux is monitored

Scoring&thresholds IFS arc line flux

The QC parameters are not scored.

Some of the laser lamp fluxed are correlated with the IFS optical bench temperature, which is monitored in a separate plot.

History

• 2019-05-27: The pipeline (version 0.37) reports only the mean initial guess resolving power. The QC script analyses the cube product and provides the best fit values in the QC1 DB for each of the four arc lines individually.
• 2017-01-01: The integrated flux of the 1.5451 mu laser lamp (= lamp #4) only covered by wavelength range of the low resolution YJH prism, shows a remarkable annual variation between 500 and 3500 ADU, while the fluxes variations of the other three laser lamps are much smaller even lower than the day-to-day variations. Given that the same 1.5451 mu laser lamp is used by the IFS imaging flat, with a much more lower rms, we conclude, that the long-term variations in the IFU spectra are not due to the lamp.

  Note that the significant annual variation of the laser lamp #4 arc line flux is not correlated with the annual variation of the optical bench temperature.

Algorithm IFS arc line flux

The QC script fits a Gaussian to each of the monochromatic laser lamp arc lines.

QC1_parameters

FITS key	QC1 database: table, name	definition	class*	HC_plot**	more docu
[QC script]	sphere_ifs_wave..dispersion	wlenbin dispersion [mu/wlenbin]	HC		[docuSys coming]
*Class: KPI - instrument performance; HC - instrument health; CAL - calibration quality; ENG - engineering parameter **There might be more than one.

Linear regression based on the Gaussian best fit positions.

Linear regression based on the Gaussian best fit positions.

Trending

Both plots for YJ . The plots show in black the pipeline resultsi and in red the best fit dispersion performed by the QC script.

Scoring&thresholds IFS dispersion

QC parameters are not scored.

History

• In 2018 the QC scripts have been tested and in 2019 put in operation in order to monitor the health of the instrument.
• From 2019-07 on the QC.DISPERSON keyword value is shows, which is the same value as given in the CD_3_3 keyword (= scale of the wavelength in the cube product). For data acquired before 2019-07 the QC.MED.DISPERS keyword value is given, which is essntially the initial guess.

Algorithm IFS dispersion

The best fit positions of arc arc lines and their wavelength bins in the cube is used to derive a linear regression to retrieve the wavelength of the first wavelength bin and the dispersion in mu/wlenbin.