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Project DR-07

Sky background correction in IR spectroscopy

The purpose of this project is to perform an evaluation of the applicability of the method developed as part of DR-06 for the correction of sky background (emission lines and continuum) on existing instruments. For SINFONI, this method can be compared to the Ric Davies’ method already implemented in the ESO pipeline.


  • Same references as DR-06, as well as
  • Davies, R.I., 2007, A method to remove residual OH emission from near-infrared spectra, Mon. Not. R. Astron. Soc. 375, 1099–1105 (2007)
  • Modigliani, et al., The SINFONI pipeline, arXiv:astro-ph/0701297


Applicable instruments and modes

A study needs to be performed to evaluate the impact of this error on existing instruments, SINFONI, and possibly ISAAC (tilt of sky lines), VIMOS, VISIR, NACO.

Required archive, calibration or observation data

Archive data.


Required algorithm developments

The basic algorithm will be the same as for DR-06. The following tasks are planned:

  1. Retrieve archive data from the above mentioned instruments (ESO will provide pipeline processed data).
  2. Define a product interface (requirements on the pipeline products for this task).
  3. Analyzing the data, test methods. For the particular case of SINFONI, the correction based on Ric Davies’s method shall be compared to the new method.
  4. Writing/debugging/documenting CPL-based code.
  5. The performance of the algorithm as a function of sky sampling, S/N and sky stability, shall be characterized.


Required software developments

All software will be developed following the guidelines of the VLT-SPE-ESO-19000-1618 document. The software delivery will include in particular the CPL-based recipes, test reports, user documentation and Reflex workflows.


The improved data reduction scheme will be compared to the results of the SINFONI, ISAAC, and VIMOS pipelines.

Institute of Astronomy
Vienna University
A-1180 Wien Türkenschanzstraße 17,
A-1180 Vienna
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