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NACO Quality Control:
Science Imaging


NACO QC Science Imaging: GENERAL

CONICA raw frames taken with any of the templates for imaging science observations (NACO_img_obs_AutoJitter, NACO_img_obs_AutoJitterOffset, NACO_img_obs_GenericOffset, NACO_img_obs_FixedSkyOffset) are pipeline processed and included in service mode packages within the ESO VLT dataflow concept. These science images contain useful information concerning instrument stability and general QC, so the QC parameters are extracted and analyzed.

  • PRODUCT_PLOT. This means that for each pipeline product and its associated raw frames we create a plot with the most significant features.
  • TRENDING. This means that we store all qc1 parameters and build Run Charts which simply show the parameter as a function of time over a larger time interval.

NACO product files follow a certain naming convention.


There follows for each lampflat product type a QC1 plot. The Figure caption is equal for all four plots.

Figure caption
Positions of all sources found by the eclipse peak command with FWHM and flux. The figure caption incudes the following QC parameters: number frames specified in the template, number of frames contributing to the product, number of object frames, number of sky frames, number of rejected frames, Histrogram of the FWHM distribution of all found sources.
Positions of the jitter offset sequence.




Trending describes the variation of a QC1 parameter within a large time range. We show a time range of 4 months and generate 4 trending plots a year. The following QC1 parameters are determined and trended.

  • SKY_BR = sky brightness as derived from the jitter recipe sky background value. The values are in units of instrumntal magnitude, meaning the zeropoint of the night is required for the remaining reduction step. Another question is if the extinction should be applied or not. The sky brightness in the IR consists of several components: sky emission lines, sky continuum, telescope and instrument contributions. While the contributions from the telescope and the instrument are independent on airmass, the sky (or better atmospheric) contributions should be as long as they originate from layers above the atmospheric layers responsible for extinction. The sky emission originates in abou 40 km height and should be subject of extinction correction. However, since the indivudual contributions cannot be distangled from each other we do not apply the extinction correction.

    SKY_BR (gif | ps)

  • STREHL = strehl ratio as derived from the PSF-CALIBRATOR frames before the acquisition of the science imaging OB. t

    STREHL per dichroic (gif | ps) and per wavefront sensor mode (gif | ps)

  • IQ= image quality. If there are objects visible in the FOV we apply the eclipse peak command and give the mode of the FWHM frequency (= the maximum of the FWHM histogram).

    IQ as given by the peak command (gif | ps) and as the mode of the FWHM distribution (gif | ps).



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