[ ESO ] La Silla

La Silla - Science Operation Department
The CES pipeline

The CES pipeline --- the former quick-look tool

The CES quick-look tool has evolved beyond a mere quick-look tool, towards pipeline functionality, although its main objective still is to provide a quick way to check the quality of the data. It is a background task running on the offline data reduction terminal so the data are automatically reduced and displayed in real time. The pipeline will perform bias subtraction and wavelength calibration before displaying the resulting spectrum in units of S/N, providing an immediate measure of the data quality. Dark correction is done with the latest (master-)dark from the calibration database. Extracted spectra are written as fits-files for easy examination.

For each pixel in the dispersion direction more than 300 pixels are summed across the dispersion, hence cosmic rays are a real problem. The pipeline removes cosmics with a simple MIDAS routine before extracting the spectrum. The spectra are not flat-fielded by default, which is a concious choice: several spectral orders are contaminated by grating ghosts, which even a simple flatfielding often can remove quite well. But for checking the data quality, it is important to be able to see that the ghost is not on top of an important spectral feature, hence we choose as default to turn off the flat fielding. However, a master-flatfield is automatically produced, and the user can choose to turn on flat-fielding at any time.

The pipeline offers the possibilty to re-reduce data. This way, observers may choose to rereduce their science frames using ThAr calibrations obtained throughout the night, and turning flatfielding on or off as desired.

Observers should be fully aware that the pipeline does not guarantee science quality reductions, and is primarily offered as a means of checking the data quality on-the-fly. For more information, please consult the CES Pipeline Manual.

Although it is foreseen that the pipeline can run on other computers for off-line reduction, this is currently not possible.

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