esorex fors_subtract_sky [OPTIONS] FILE.sof


This recipe is used to subtract the sky emission from unrebinned slit spectra. This is obtained by robust fitting (i.e., excluding the signal from possible point-like objects in slit) of the emission along the CCD columns within each spectrum). This method doesn\'t work if extended objects are in slit (it really destroys the object spectra), and is not applicable to LSS data. The input scientific frames are produced by the recipes fors_remove_bias and fors_flatfield.

This recipe cannot be applied to LSS or long-slit like data (MOS/MXU with all slits at the same offset). No automatic recipe is available for this.

Please refer to the FORS Pipeline User\'s Manual for more details.

In the table below the MXU acronym can be alternatively read as MOS, and SCI as STD.

Input files:

  DO category:               Type:       Explanation:         Required:
  or STANDARD_UNFLAT_MXU     Calib       Frame with sky lines    Y
  CURV_COEFF_MXU             Calib       Spectral curvature      Y
  SLIT_LOCATION_MXU          Calib       Slit location on CCD    Y
  GRISM_TABLE                Calib       Grism table             .

Output files:

  DO category:               Data type:  Explanation:
  or UNMAPPED_STD_MXU        FITS image  Sky subtracted scientific frame
  or UNMAPPED_SKY_STD_MXU    FITS image  Subtracted sky frame


--dispersion <float>

Expected spectral dispersion (Angstrom/pixel) (float; default: 0.0). The full name of this option for the EsoRex configuration file is fors.fors_subtract_sky.dispersion [default = 0.0].

--startwavelength <float>

Start wavelength in spectral extraction (float; default: 0.0). The full name of this option for the EsoRex configuration file is fors.fors_subtract_sky.startwavelength [default = 0.0].

--endwavelength <float>

End wavelength in spectral extraction (float; default: 0.0). The full name of this option for the EsoRex configuration file is fors.fors_subtract_sky.endwavelength [default = 0.0].

--cosmics <bool>

Eliminate cosmic rays hits (bool; default: False). The full name of this option for the EsoRex configuration file is fors.fors_subtract_sky.cosmics [default = False].

Note that it is possible to create a configuration file containing these options, along with suitable default values. Please refer to the details provided by the 'esorex --help' command.

RELATED TO fors_subtract_sky…

The full documentation for the fors pipeline can be downloaded as a PDF file using the following URL:


An overview over the existing ESO pipelines can be found on the web page

Basic documentation about the EsoRex program can be found at the esorex (1) man page.

It is possible to call the pipelines from python using the python-cpl package. See for further information.

The other recipes of the fors pipeline are fors_wave_calib_lss(7), fors_img_sky_flat(7), fors_resample(7), fors_config(7), fors_extract_objects(7), fors_calib(7), fors_wave_calib(7), fors_detect_objects(7), fors_pmos_science(7), fors_extract_slits(7), test_hough(7), fors_img_screen_flat(7), fors_extract(7), fors_remove_bias(7), fors_normalise_flat(7), montecarlo(7), fors_photometry(7), fors_zeropoint(7), fors_dark(7), fors_subtract_sky_lss(7), fors_trace_flat(7), fors_flatfield(7), fors_img_science(7), fors_detect_spectra(7), fors_sumflux(7), fors_pmos_extract(7), fors_align_sky_lss(7), fors_bias(7), fors_align_sky(7), fors_pmos_calib(7), fors_spec_mflat(7), fors_science(7)


fors_subtract_sky 5.0.0


Carlo Izzo <[email protected]>


Please report any problems to [email protected] Alternatively, you may send a report to the ESO User Support Department <[email protected]>.


This file is currently part of the FORS Instrument Pipeline Copyright (C) 2002-2010 European Southern Observatory

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