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NIFS performance monitoring

NIFS

 

  • Throughput: Observation required are spectra of well-calibrated NIR spectrophotometric standards, using all four available grating+filter combinations. Observations can be executed in twilight, but photometric conditions are required. Data are collected every three months.

     

  • Image quality with ALTAIR: Observation of a star with R ≤ 12 to establish the on-axis image quality when guiding with ALTAIR. Same observations obtained for throughput determination can be used for this. Frequency is once every three months.

     

  • Detector Noise: Characterization and monitoring of detector noise. Data consist of short dark exposures for each of the three readout modes. Statistics for each of the four readout sectors are measured and stored separately. These are part of standard daytime checks.

     

  • Detector cosmetics: Observations required are dark exposures. They will consist of three long (600 sec) dark observations, which are taken taken once a month. The need for a high frequency is due to the fact that NIFS detectors are particularly affected by cosmetic defects.

     

  • Detector linearity: Observations consist of flat-fields with varying exposure times. Measured counts should be compared with expectations for linear response. Only one instrument configuration is required. Data collected once a year.

     

  • Spectral Resolution and PSF: Observations combine internal lamp data and telluric emission lines from blank sky exposures in order to measure and monitor the spectral resolution and PSF as a function of wavelength and position in the NIFS field. Observations are collected once every three months and tolerate any conditions.