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Quality Control and
Data Processing
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KMOS: Wavelength calibration
Arc-lamp calibrations are measured during daytime for the five wavelength bands IZ, YJ, H, HK, and K and for six different rotator angles. A standard calibration sequence uses rotator angles of -60 (i.e. 300), 0, 60, 120, 180, and 240 degrees. Two lamps are used simultaneously: one Argon and one Neon lamp. Each IFU comprises 14 slices. Eight IFUs form a sub group which is mapped on a single slit. The light is then dispersed through one of the three spectrographs and recorded on one detector array (out of three). There are three independent optical channels, each having eight IFUs.
Spectral resolution
KMOS arc-lamp frames are usually taken at six different rotator angles. These fill the QC parameters, for example ar_fwhm_mean__1, ar_fwhm_mean_2, ..., ar_fwhm_mean_6, etc. The actual angles can be found in the parameters rot_angle_1, rot_angle_2, ..., rot_angle_6. The parameter ar_fwhm_mean_0 is only filled if a measurement at 0 degree rotator angle is present which is typically the case for daytime calibrations.
The spectral resolution is monitored for Ar and Ne lines separately. Trending is performed for all five spectral bands. The QC parameters at 0 degree rotator angle (ar_fwhm_mean_0, ne_fwhm_mean_0) are plotted versus time and scored. The dependency from rotator angle is shown in separate plots (not scored). Scoring&thresholds Spectral resolution The QC parameters at 0 degree rotator angle (ar_fwhm_mean_0, ne_fwhm_mean_0) are scored. Scoring thresholds have been set empirically to +/- 3 sigma around the median (determined from data taken between 15 August and 30 November 2018). Small changes in spectral resolutions could be observed sometimes after interventions. Average FWHM of arc lines, calculated separately for Ar and Ne lines and converted to km/sec.
Wavelength solution
The mean deviation of the line positions is monitored for Ar and Ne. Trending is performed for all five spectral bands. The QC parameters at 0 degree rotator angle (ar_pos_mean_0, ne_pos_mean_0) are plotted versus time. The dependency from rotator angle is shown in separate plots. Scoring&thresholds Wavelength solution Scoring is not implemented. The wavelength solution was stable over time. As a measure of the quality of the wavelength calibration, the deviation (in km/s) of the actual line positions from the fitted wavelength solution is calculated.
Arc-lamp performance
The lamp flux is monitored in the YJ band separately for Ar and Ne and for all three optical channels. The parameters ar_eff_0 and ne_eff_0, respectively, are trended versus time. Since the efficiency does not strongly depend on rotator angle, only ar_eff_0 and ne_eff_0 are scored. The dependency against rotator angle is shown in separate plots. Scoring&thresholds Arc-lamp performance The QC parameters at 0 degree rotator angle (ar_eff_0, ne_eff_0) are scored. Thresholds have been set empirically. A lamp flux that is approaching the upper limit is typically an indication that the lamp is at the end of its life time. The Neon lamp had to be exchanged a few times. It typically lasts up to 18 months. Algorithm Arc-lamp performance Pipeline calculated average flux of arc lines, converted to e-/sec.
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